Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 1724 insertions, 0 deletions

diff --git a/Documentation/cdrom/00-INDEX b/Documentation/cdrom/00-INDEX
new file mode 100644
index 000000000..433edf23d
--- /dev/null
+++ b/Documentation/cdrom/00-INDEX
@@ -0,0 +1,11 @@
+00-INDEX
+	- this file (info on CD-ROMs and Linux)
+Makefile
+	- only used to generate TeX output from the documentation.
+cdrom-standard.tex
+	- LaTeX document on standardizing the CD-ROM programming interface.
+ide-cd
+	- info on setting up and using ATAPI (aka IDE) CD-ROMs.
+packet-writing.txt
+	- Info on the CDRW packet writing module
+
diff --git a/Documentation/cdrom/Makefile b/Documentation/cdrom/Makefile
new file mode 100644
index 000000000..a19e32192
--- /dev/null
+++ b/Documentation/cdrom/Makefile
@@ -0,0 +1,21 @@
+LATEXFILE = cdrom-standard
+
+all:
+	make clean
+	latex $(LATEXFILE)
+	latex $(LATEXFILE)
+	@if [ -x `which gv` ]; then \
+		`dvips -q -t letter -o $(LATEXFILE).ps $(LATEXFILE).dvi` ;\
+		`gv -antialias -media letter -nocenter $(LATEXFILE).ps` ;\
+	else \
+		`xdvi $(LATEXFILE).dvi &` ;\
+	fi
+	make sortofclean
+
+clean:
+	rm -f $(LATEXFILE).ps $(LATEXFILE).dvi $(LATEXFILE).aux $(LATEXFILE).log 
+
+sortofclean:
+	rm -f $(LATEXFILE).aux $(LATEXFILE).log 
+
+
diff --git a/Documentation/cdrom/cdrom-standard.tex b/Documentation/cdrom/cdrom-standard.tex
new file mode 100644
index 000000000..f7cd45597
--- /dev/null
+++ b/Documentation/cdrom/cdrom-standard.tex
@@ -0,0 +1,1026 @@
+\documentclass{article}
+\def\version{$Id: cdrom-standard.tex,v 1.9 1997/12/28 15:42:49 david Exp $}
+\newcommand{\newsection}[1]{\newpage\section{#1}}
+
+\evensidemargin=0pt
+\oddsidemargin=0pt
+\topmargin=-\headheight \advance\topmargin by -\headsep
+\textwidth=15.99cm \textheight=24.62cm % normal A4, 1'' margin
+
+\def\linux{{\sc Linux}}
+\def\cdrom{{\sc cd-rom}}
+\def\UCD{{\sc Uniform cd-rom Driver}}
+\def\cdromc{{\tt {cdrom.c}}}
+\def\cdromh{{\tt {cdrom.h}}}
+\def\fo{\sl}                    % foreign words
+\def\ie{{\fo i.e.}}
+\def\eg{{\fo e.g.}}
+
+\everymath{\it} \everydisplay{\it}
+\catcode `\_=\active \def_{\_\penalty100 }
+\catcode`\<=\active \def<#1>{{\langle\hbox{\rm#1}\rangle}}
+
+\begin{document}
+\title{A \linux\ \cdrom\ standard}
+\author{David van Leeuwen\\{\normalsize\tt david@ElseWare.cistron.nl}
+\\{\footnotesize updated by Erik Andersen {\tt(andersee@debian.org)}}
+\\{\footnotesize updated by Jens Axboe {\tt(axboe@image.dk)}}}
+\date{12 March 1999}
+
+\maketitle
+
+\newsection{Introduction}
+
+\linux\ is probably the Unix-like operating system that supports
+the widest variety of hardware devices. The reasons for this are
+presumably 
+\begin{itemize} 
+\item 
+  The large list of hardware devices available for the many platforms
+  that \linux\ now supports (\ie, i386-PCs, Sparc Suns, etc.)
+\item 
+  The open design of the operating system, such that anybody can write a
+  driver for \linux.
+\item 
+  There is plenty of source code around as examples of how to write a driver.
+\end{itemize}
+The openness of \linux, and the many different types of available
+hardware has allowed \linux\ to support many different hardware devices.
+Unfortunately, the very openness that has allowed \linux\ to support
+all these different devices has also allowed the behavior of each
+device driver to differ significantly from one device to another.
+This divergence of behavior has been very significant for \cdrom\
+devices; the way a particular drive reacts to a `standard' $ioctl()$
+call varies greatly from one device driver to another. To avoid making
+their drivers totally inconsistent, the writers of \linux\ \cdrom\
+drivers generally created new device drivers by understanding, copying,
+and then changing an existing one. Unfortunately, this practice did not
+maintain uniform behavior across all the \linux\ \cdrom\ drivers. 
+
+This document describes an effort to establish Uniform behavior across
+all the different \cdrom\ device drivers for \linux. This document also
+defines the various $ioctl$s, and how the low-level \cdrom\ device
+drivers should implement them. Currently (as of the \linux\ 2.1.$x$
+development kernels) several low-level \cdrom\ device drivers, including
+both IDE/ATAPI and SCSI, now use this Uniform interface.
+
+When the \cdrom\ was developed, the interface between the \cdrom\ drive
+and the computer was not specified in the standards. As a result, many
+different \cdrom\ interfaces were developed. Some of them had their
+own proprietary design (Sony, Mitsumi, Panasonic, Philips), other
+manufacturers adopted an existing electrical interface and changed
+the functionality (CreativeLabs/SoundBlaster, Teac, Funai) or simply
+adapted their drives to one or more of the already existing electrical
+interfaces (Aztech, Sanyo, Funai, Vertos, Longshine, Optics Storage and
+most of the `NoName' manufacturers). In cases where a new drive really
+brought its own interface or used its own command set and flow control
+scheme, either a separate driver had to be written, or an existing
+driver had to be enhanced. History has delivered us \cdrom\ support for
+many of these different interfaces. Nowadays, almost all new \cdrom\
+drives are either IDE/ATAPI or SCSI, and it is very unlikely that any
+manufacturer will create a new interface. Even finding drives for the
+old proprietary interfaces is getting difficult.
+
+When (in the 1.3.70's) I looked at the existing software interface,
+which was expressed through \cdromh, it appeared to be a rather wild
+set of commands and data formats.\footnote{I cannot recollect what
+kernel version I looked at, then, presumably 1.2.13 and 1.3.34---the
+latest kernel that I was indirectly involved in.} It seemed that many
+features of the software interface had been added to accommodate the
+capabilities of a particular drive, in an {\fo ad hoc\/} manner. More
+importantly, it appeared that the behavior of the `standard' commands
+was different for most of the different drivers: \eg, some drivers
+close the tray if an $open()$ call occurs when the tray is open, while
+others do not. Some drivers lock the door upon opening the device, to
+prevent an incoherent file system, but others don't, to allow software
+ejection. Undoubtedly, the capabilities of the different drives vary,
+but even when two drives have the same capability their drivers'
+behavior was usually different.
+
+I decided to start a discussion on how to make all the \linux\ \cdrom\
+drivers behave more uniformly. I began by contacting the developers of
+the many \cdrom\ drivers found in the \linux\ kernel. Their reactions
+encouraged me to write the \UCD\ which this document is intended to
+describe. The implementation of the \UCD\ is in the file \cdromc. This
+driver is intended to be an additional software layer that sits on top
+of the low-level device drivers for each \cdrom\ drive. By adding this
+additional layer, it is possible to have all the different \cdrom\
+devices behave {\em exactly\/} the same (insofar as the underlying
+hardware will allow).
+
+The goal of the \UCD\ is {\em not\/} to alienate driver developers who
+have not yet taken steps to support this effort. The goal of \UCD\ is
+simply to give people writing application programs for \cdrom\ drives
+{\em one\/} \linux\ \cdrom\ interface with consistent behavior for all
+\cdrom\ devices. In addition, this also provides a consistent interface
+between the low-level device driver code and the \linux\ kernel. Care
+is taken that 100\,\% compatibility exists with the data structures and
+programmer's interface defined in \cdromh. This guide was written to
+help \cdrom\ driver developers adapt their code to use the \UCD\ code
+defined in \cdromc.
+
+Personally, I think that the most important hardware interfaces are
+the IDE/ATAPI drives and, of course, the SCSI drives, but as prices
+of hardware drop continuously, it is also likely that people may have
+more than one \cdrom\ drive, possibly of mixed types. It is important
+that these drives behave in the same way. In December 1994, one of the
+cheapest \cdrom\ drives was a Philips cm206, a double-speed proprietary
+drive. In the months that I was busy writing a \linux\ driver for it,
+proprietary drives became obsolete and IDE/ATAPI drives became the
+standard. At the time of the last update to this document (November
+1997) it is becoming difficult to even {\em find} anything less than a
+16 speed \cdrom\ drive, and 24 speed drives are common.
+
+\newsection{Standardizing through another software level}
+\label{cdrom.c}
+
+At the time this document was conceived, all drivers directly
+implemented the \cdrom\ $ioctl()$ calls through their own routines. This
+led to the danger of different drivers forgetting to do important things
+like checking that the user was giving the driver valid data. More
+importantly, this led to the divergence of behavior, which has already
+been discussed.
+
+For this reason, the \UCD\ was created to enforce consistent \cdrom\
+drive behavior, and to provide a common set of services to the various
+low-level \cdrom\ device drivers. The \UCD\ now provides another
+software-level, that separates the $ioctl()$ and $open()$ implementation
+from the actual hardware implementation. Note that this effort has
+made few changes which will affect a user's application programs. The
+greatest change involved moving the contents of the various low-level
+\cdrom\ drivers' header files to the kernel's cdrom directory. This was
+done to help ensure that the user is only presented with only one cdrom
+interface, the interface defined in \cdromh.
+
+\cdrom\ drives are specific enough (\ie, different from other
+block-devices such as floppy or hard disc drives), to define a set
+of common {\em \cdrom\ device operations}, $<cdrom-device>_dops$.
+These operations are different from the classical block-device file
+operations, $<block-device>_fops$.
+
+The routines for the \UCD\ interface level are implemented in the file
+\cdromc. In this file, the \UCD\ interfaces with the kernel as a block
+device by registering the following general $struct\ file_operations$:
+$$
+\halign{$#$\ \hfil&$#$\ \hfil&$/*$ \rm# $*/$\hfil\cr
+struct& file_operations\ cdrom_fops = \{\hidewidth\cr
+        &NULL,                  & lseek \cr
+        &block_read,            & read---general block-dev read \cr
+        &block_write,           & write---general block-dev write \cr
+        &NULL,                  & readdir \cr
+        &NULL,                  & select \cr
+        &cdrom_ioctl,           & ioctl \cr
+        &NULL,                  & mmap \cr
+        &cdrom_open,            & open \cr
+        &cdrom_release,         & release \cr
+        &NULL,                  & fsync \cr
+        &NULL,                  & fasync \cr
+        &cdrom_media_changed,   & media change \cr
+        &NULL                   & revalidate \cr
+\};\cr
+}
+$$ 
+
+Every active \cdrom\ device shares this $struct$. The routines
+declared above are all implemented in \cdromc, since this file is the
+place where the behavior of all \cdrom-devices is defined and
+standardized. The actual interface to the various types of \cdrom\ 
+hardware is still performed by various low-level \cdrom-device
+drivers. These routines simply implement certain {\em capabilities\/}
+that are common to all \cdrom\ (and really, all removable-media
+devices).
+
+Registration of a low-level \cdrom\ device driver is now done through
+the general routines in \cdromc, not through the Virtual File System
+(VFS) any more. The interface implemented in \cdromc\ is carried out
+through two general structures that contain information about the
+capabilities of the driver, and the specific drives on which the
+driver operates. The structures are:
+\begin{description}
+\item[$cdrom_device_ops$] 
+  This structure contains information about the low-level driver for a
+  \cdrom\ device. This structure is conceptually connected to the major
+  number of the device (although some drivers may have different
+  major numbers, as is the case for the IDE driver).
+\item[$cdrom_device_info$] 
+  This structure contains information about a particular \cdrom\ drive,
+  such as its device name, speed, etc. This structure is conceptually
+  connected to the minor number of the device.
+\end{description}
+
+Registering a particular \cdrom\ drive with the \UCD\ is done by the
+low-level device driver though a call to:
+$$register_cdrom(struct\ cdrom_device_info * <device>_info)  
+$$
+The device information structure, $<device>_info$, contains all the
+information needed for the kernel to interface with the low-level
+\cdrom\ device driver. One of the most important entries in this
+structure is a pointer to the $cdrom_device_ops$ structure of the
+low-level driver.
+
+The device operations structure, $cdrom_device_ops$, contains a list
+of pointers to the functions which are implemented in the low-level
+device driver. When \cdromc\ accesses a \cdrom\ device, it does it
+through the functions in this structure. It is impossible to know all
+the capabilities of future \cdrom\ drives, so it is expected that this
+list may need to be expanded from time to time as new technologies are
+developed. For example, CD-R and CD-R/W drives are beginning to become
+popular, and support will soon need to be added for them. For now, the
+current $struct$ is:
+$$
+\halign{$#$\ \hfil&$#$\ \hfil&\hbox to 10em{$#$\hss}&
+  $/*$ \rm# $*/$\hfil\cr
+struct& cdrom_device_ops\ \{ \hidewidth\cr
+  &int& (* open)(struct\ cdrom_device_info *, int)\cr
+  &void& (* release)(struct\ cdrom_device_info *);\cr 
+  &int& (* drive_status)(struct\ cdrom_device_info *, int);\cr     
+  &unsigned\ int& (* check_events)(struct\ cdrom_device_info *, unsigned\ int, int);\cr
+  &int& (* media_changed)(struct\ cdrom_device_info *, int);\cr 
+  &int& (* tray_move)(struct\ cdrom_device_info *, int);\cr
+  &int& (* lock_door)(struct\ cdrom_device_info *, int);\cr
+  &int& (* select_speed)(struct\ cdrom_device_info *, int);\cr
+  &int& (* select_disc)(struct\ cdrom_device_info *, int);\cr
+  &int& (* get_last_session) (struct\ cdrom_device_info *, 
+        struct\ cdrom_multisession *{});\cr
+  &int& (* get_mcn)(struct\ cdrom_device_info *, struct\ cdrom_mcn *{});\cr
+  &int& (* reset)(struct\ cdrom_device_info *);\cr
+  &int& (* audio_ioctl)(struct\ cdrom_device_info *, unsigned\ int, 
+        void *{});\cr 
+\noalign{\medskip}
+  &const\ int& capability;& capability flags \cr
+  &int& (* generic_packet)(struct\ cdrom_device_info *, struct\ packet_command *{});\cr
+\};\cr
+}
+$$
+When a low-level device driver implements one of these capabilities,
+it should add a function pointer to this $struct$. When a particular
+function is not implemented, however, this $struct$ should contain a
+NULL instead. The $capability$ flags specify the capabilities of the
+\cdrom\ hardware and/or low-level \cdrom\ driver when a \cdrom\ drive
+is registered with the \UCD.
+
+Note that most functions have fewer parameters than their
+$blkdev_fops$ counterparts. This is because very little of the
+information in the structures $inode$ and $file$ is used. For most
+drivers, the main parameter is the $struct$ $cdrom_device_info$, from
+which the major and minor number can be extracted. (Most low-level
+\cdrom\ drivers don't even look at the major and minor number though,
+since many of them only support one device.) This will be available
+through $dev$ in $cdrom_device_info$ described below.
+
+The drive-specific, minor-like information that is registered with
+\cdromc, currently contains the following fields:
+$$
+\halign{$#$\ \hfil&$#$\ \hfil&\hbox to 10em{$#$\hss}&
+  $/*$ \rm# $*/$\hfil\cr
+struct& cdrom_device_info\ \{ \hidewidth\cr
+  & const\ struct\ cdrom_device_ops *& ops;& device operations for this major\cr
+  & struct\ list_head& list;& linked list of all device_info\cr
+  & struct\ gendisk *& disk;& matching block layer disk\cr
+  & void *&  handle;& driver-dependent data\cr
+\noalign{\medskip}
+  & int& mask;& mask of capability: disables them \cr
+  & int& speed;& maximum speed for reading data \cr
+  & int& capacity;& number of discs in a jukebox \cr
+\noalign{\medskip}
+  &unsigned\ int& options : 30;& options flags \cr
+  &unsigned& mc_flags : 2;& media-change buffer flags \cr
+  &unsigned\ int& vfs_events;& cached events for vfs path\cr
+  &unsigned\ int& ioctl_events;& cached events for ioctl path\cr
+  & int& use_count;& number of times device is opened\cr
+  & char& name[20];& name of the device type\cr
+\noalign{\medskip}
+  &__u8& sanyo_slot : 2;& Sanyo 3-CD changer support\cr
+  &__u8& keeplocked : 1;& CDROM_LOCKDOOR status\cr
+  &__u8& reserved : 5;& not used yet\cr
+  & int& cdda_method;& see CDDA_* flags\cr
+  &__u8& last_sense;& saves last sense key\cr
+  &__u8& media_written;& dirty flag, DVD+RW bookkeeping\cr
+  &unsigned\ short& mmc3_profile;& current MMC3 profile\cr
+  & int& for_data;& unknown:TBD\cr
+  & int\ (* exit)\ (struct\ cdrom_device_info *);&& unknown:TBD\cr
+  & int& mrw_mode_page;& which MRW mode page is in use\cr
+\}\cr
+}$$
+Using this $struct$, a linked list of the registered minor devices is
+built, using the $next$ field. The device number, the device operations
+struct and specifications of properties of the drive are stored in this
+structure.
+
+The $mask$ flags can be used to mask out some of the capabilities listed
+in $ops\to capability$, if a specific drive doesn't support a feature
+of the driver. The value $speed$ specifies the maximum head-rate of the
+drive, measured in units of normal audio speed (176\,kB/sec raw data or
+150\,kB/sec file system data).  The parameters are declared $const$
+because they describe properties of the drive, which don't change after
+registration.
+
+A few registers contain variables local to the \cdrom\ drive. The
+flags $options$ are used to specify how the general \cdrom\ routines
+should behave. These various flags registers should provide enough
+flexibility to adapt to the different users' wishes (and {\em not\/} the
+`arbitrary' wishes of the author of the low-level device driver, as is
+the case in the old scheme). The register $mc_flags$ is used to buffer
+the information from $media_changed()$ to two separate queues. Other
+data that is specific to a minor drive, can be accessed through $handle$,
+which can point to a data structure specific to the low-level driver.
+The fields $use_count$, $next$, $options$ and $mc_flags$ need not be
+initialized.
+
+The intermediate software layer that \cdromc\ forms will perform some
+additional bookkeeping. The use count of the device (the number of
+processes that have the device opened) is registered in $use_count$. The
+function $cdrom_ioctl()$ will verify the appropriate user-memory regions
+for read and write, and in case a location on the CD is transferred,
+it will `sanitize' the format by making requests to the low-level
+drivers in a standard format, and translating all formats between the
+user-software and low level drivers. This relieves much of the drivers'
+memory checking and format checking and translation. Also, the necessary
+structures will be declared on the program stack.
+
+The implementation of the functions should be as defined in the
+following sections. Two functions {\em must\/} be implemented, namely
+$open()$ and $release()$. Other functions may be omitted, their
+corresponding capability flags will be cleared upon registration.
+Generally, a function returns zero on success and negative on error. A
+function call should return only after the command has completed, but of
+course waiting for the device should not use processor time.
+
+\subsection{$Int\ open(struct\ cdrom_device_info * cdi, int\ purpose)$}
+
+$Open()$ should try to open the device for a specific $purpose$, which
+can be either:
+\begin{itemize}
+\item[0] Open for reading data, as done by {\tt {mount()}} (2), or the
+user commands {\tt {dd}} or {\tt {cat}}.  
+\item[1] Open for $ioctl$ commands, as done by audio-CD playing
+programs.
+\end{itemize}
+Notice that any strategic code (closing tray upon $open()$, etc.)\ is
+done by the calling routine in \cdromc, so the low-level routine
+should only be concerned with proper initialization, such as spinning
+up the disc, etc. % and device-use count
+
+
+\subsection{$Void\ release(struct\ cdrom_device_info * cdi)$}
+
+
+Device-specific actions should be taken such as spinning down the device.
+However, strategic actions such as ejection of the tray, or unlocking
+the door, should be left over to the general routine $cdrom_release()$.
+This is the only function returning type $void$.
+
+\subsection{$Int\ drive_status(struct\ cdrom_device_info * cdi, int\ slot_nr)$}
+\label{drive status}
+
+The function $drive_status$, if implemented, should provide
+information on the status of the drive (not the status of the disc,
+which may or may not be in the drive). If the drive is not a changer,
+$slot_nr$ should be ignored. In \cdromh\ the possibilities are listed: 
+$$
+\halign{$#$\ \hfil&$/*$ \rm# $*/$\hfil\cr
+CDS_NO_INFO& no information available\cr
+CDS_NO_DISC& no disc is inserted, tray is closed\cr
+CDS_TRAY_OPEN& tray is opened\cr
+CDS_DRIVE_NOT_READY& something is wrong, tray is moving?\cr
+CDS_DISC_OK& a disc is loaded and everything is fine\cr
+}
+$$
+
+\subsection{$Int\ media_changed(struct\ cdrom_device_info * cdi, int\ disc_nr)$}
+
+This function is very similar to the original function in $struct\ 
+file_operations$. It returns 1 if the medium of the device $cdi\to
+dev$ has changed since the last call, and 0 otherwise. The parameter
+$disc_nr$ identifies a specific slot in a juke-box, it should be
+ignored for single-disc drives.  Note that by `re-routing' this
+function through $cdrom_media_changed()$, we can implement separate
+queues for the VFS and a new $ioctl()$ function that can report device
+changes to software (\eg, an auto-mounting daemon).
+
+\subsection{$Int\ tray_move(struct\ cdrom_device_info * cdi, int\ position)$}
+
+This function, if implemented, should control the tray movement. (No
+other function should control this.) The parameter $position$ controls
+the desired direction of movement:
+\begin{itemize}
+\item[0] Close tray
+\item[1] Open tray
+\end{itemize}
+This function returns 0 upon success, and a non-zero value upon
+error. Note that if the tray is already in the desired position, no
+action need be taken, and the return value should be 0. 
+
+\subsection{$Int\ lock_door(struct\ cdrom_device_info * cdi, int\ lock)$}
+
+This function (and no other code) controls locking of the door, if the
+drive allows this. The value of $lock$ controls the desired locking
+state:
+\begin{itemize}
+\item[0] Unlock door, manual opening is allowed
+\item[1] Lock door, tray cannot be ejected manually
+\end{itemize}
+This function returns 0 upon success, and a non-zero value upon
+error. Note that if the door is already in the requested state, no
+action need be taken, and the return value should be 0. 
+
+\subsection{$Int\ select_speed(struct\ cdrom_device_info * cdi, int\ speed)$}
+
+Some \cdrom\ drives are capable of changing their head-speed. There
+are several reasons for changing the speed of a \cdrom\ drive. Badly
+pressed \cdrom s may benefit from less-than-maximum head rate. Modern
+\cdrom\ drives can obtain very high head rates (up to $24\times$ is
+common).  It has been reported that these drives can make reading
+errors at these high speeds, reducing the speed can prevent data loss
+in these circumstances.  Finally, some of these drives can
+make an annoyingly loud noise, which a lower speed may reduce. %Finally,
+%although the audio-low-pass filters probably aren't designed for it,
+%more than real-time playback of audio might be used for high-speed
+%copying of audio tracks.
+
+This function specifies the speed at which data is read or audio is
+played back. The value of $speed$ specifies the head-speed of the
+drive, measured in units of standard cdrom speed (176\,kB/sec raw data
+or 150\,kB/sec file system data). So to request that a \cdrom\ drive
+operate at 300\,kB/sec you would call the CDROM_SELECT_SPEED $ioctl$
+with $speed=2$. The special value `0' means `auto-selection', \ie,
+maximum data-rate or real-time audio rate. If the drive doesn't have
+this `auto-selection' capability, the decision should be made on the
+current disc loaded and the return value should be positive. A negative
+return value indicates an error.
+
+\subsection{$Int\ select_disc(struct\ cdrom_device_info * cdi, int\ number)$}
+
+If the drive can store multiple discs (a juke-box) this function
+will perform disc selection. It should return the number of the
+selected disc on success, a negative value on error. Currently, only
+the ide-cd driver supports this functionality.
+
+\subsection{$Int\ get_last_session(struct\ cdrom_device_info * cdi, struct\
+  cdrom_multisession * ms_info)$}
+
+This function should implement the old corresponding $ioctl()$. For
+device $cdi\to dev$, the start of the last session of the current disc
+should be returned in the pointer argument $ms_info$. Note that
+routines in \cdromc\ have sanitized this argument: its requested
+format will {\em always\/} be of the type $CDROM_LBA$ (linear block
+addressing mode), whatever the calling software requested. But
+sanitization goes even further: the low-level implementation may
+return the requested information in $CDROM_MSF$ format if it wishes so
+(setting the $ms_info\rightarrow addr_format$ field appropriately, of
+course) and the routines in \cdromc\ will make the transformation if
+necessary. The return value is 0 upon success.
+
+\subsection{$Int\ get_mcn(struct\ cdrom_device_info * cdi, struct\
+  cdrom_mcn * mcn)$}
+
+Some discs carry a `Media Catalog Number' (MCN), also called
+`Universal Product Code' (UPC). This number should reflect the number
+that is generally found in the bar-code on the product. Unfortunately,
+the few discs that carry such a number on the disc don't even use the
+same format. The return argument to this function is a pointer to a
+pre-declared memory region of type $struct\ cdrom_mcn$. The MCN is
+expected as a 13-character string, terminated by a null-character.
+
+\subsection{$Int\ reset(struct\ cdrom_device_info * cdi)$}
+
+This call should perform a hard-reset on the drive (although in
+circumstances that a hard-reset is necessary, a drive may very well not
+listen to commands anymore). Preferably, control is returned to the
+caller only after the drive has finished resetting. If the drive is no
+longer listening, it may be wise for the underlying low-level cdrom
+driver to time out.
+
+\subsection{$Int\ audio_ioctl(struct\ cdrom_device_info * cdi, unsigned\
+  int\ cmd, void * arg)$}
+
+Some of the \cdrom-$ioctl$s defined in \cdromh\ can be
+implemented by the routines described above, and hence the function
+$cdrom_ioctl$ will use those. However, most $ioctl$s deal with
+audio-control. We have decided to leave these to be accessed through a
+single function, repeating the arguments $cmd$ and $arg$. Note that
+the latter is of type $void*{}$, rather than $unsigned\ long\
+int$. The routine $cdrom_ioctl()$ does do some useful things,
+though. It sanitizes the address format type to $CDROM_MSF$ (Minutes,
+Seconds, Frames) for all audio calls. It also verifies the memory
+location of $arg$, and reserves stack-memory for the argument. This
+makes implementation of the $audio_ioctl()$ much simpler than in the
+old driver scheme. For example, you may look up the function
+$cm206_audio_ioctl()$ in {\tt {cm206.c}} that should be updated with
+this documentation. 
+
+An unimplemented ioctl should return $-ENOSYS$, but a harmless request
+(\eg, $CDROMSTART$) may be ignored by returning 0 (success). Other
+errors should be according to the standards, whatever they are. When
+an error is returned by the low-level driver, the \UCD\ tries whenever
+possible to return the error code to the calling program. (We may decide
+to sanitize the return value in $cdrom_ioctl()$ though, in order to
+guarantee a uniform interface to the audio-player software.)
+
+\subsection{$Int\ dev_ioctl(struct\ cdrom_device_info * cdi, unsigned\ int\
+  cmd, unsigned\ long\ arg)$}
+
+Some $ioctl$s seem to be specific to certain \cdrom\ drives. That is,
+they are introduced to service some capabilities of certain drives. In
+fact, there are 6 different $ioctl$s for reading data, either in some
+particular kind of format, or audio data. Not many drives support
+reading audio tracks as data, I believe this is because of protection
+of copyrights of artists. Moreover, I think that if audio-tracks are
+supported, it should be done through the VFS and not via $ioctl$s. A
+problem here could be the fact that audio-frames are 2352 bytes long,
+so either the audio-file-system should ask for 75264 bytes at once
+(the least common multiple of 512 and 2352), or the drivers should
+bend their backs to cope with this incoherence (to which I would be
+opposed).  Furthermore, it is very difficult for the hardware to find
+the exact frame boundaries, since there are no synchronization headers
+in audio frames.  Once these issues are resolved, this code should be
+standardized in \cdromc.
+
+Because there are so many $ioctl$s that seem to be introduced to
+satisfy certain drivers,\footnote{Is there software around that
+  actually uses these? I'd be interested!} any `non-standard' $ioctl$s
+are routed through the call $dev_ioctl()$. In principle, `private'
+$ioctl$s should be numbered after the device's major number, and not
+the general \cdrom\ $ioctl$ number, {\tt {0x53}}. Currently the
+non-supported $ioctl$s are: {\it CDROMREADMODE1, CDROMREADMODE2,
+  CDROMREADAUDIO, CDROMREADRAW, CDROMREADCOOKED, CDROMSEEK,
+  CDROMPLAY\-BLK and CDROM\-READALL}.
+
+
+\subsection{\cdrom\ capabilities}
+\label{capability}
+
+Instead of just implementing some $ioctl$ calls, the interface in
+\cdromc\ supplies the possibility to indicate the {\em capabilities\/}
+of a \cdrom\ drive. This can be done by ORing any number of
+capability-constants that are defined in \cdromh\ at the registration
+phase. Currently, the capabilities are any of:
+$$
+\halign{$#$\ \hfil&$/*$ \rm# $*/$\hfil\cr
+CDC_CLOSE_TRAY& can close tray by software control\cr
+CDC_OPEN_TRAY& can open tray\cr
+CDC_LOCK& can lock and unlock the door\cr
+CDC_SELECT_SPEED& can select speed, in units of $\sim$150\,kB/s\cr
+CDC_SELECT_DISC& drive is juke-box\cr
+CDC_MULTI_SESSION& can read sessions $>\rm1$\cr
+CDC_MCN& can read Media Catalog Number\cr
+CDC_MEDIA_CHANGED& can report if disc has changed\cr
+CDC_PLAY_AUDIO& can perform audio-functions (play, pause, etc)\cr
+CDC_RESET& hard reset device\cr
+CDC_IOCTLS& driver has non-standard ioctls\cr
+CDC_DRIVE_STATUS& driver implements drive status\cr
+}
+$$
+The capability flag is declared $const$, to prevent drivers from
+accidentally tampering with the contents. The capability fags actually
+inform \cdromc\ of what the driver can do. If the drive found
+by the driver does not have the capability, is can be masked out by
+the $cdrom_device_info$ variable $mask$. For instance, the SCSI \cdrom\
+driver has implemented the code for loading and ejecting \cdrom's, and
+hence its corresponding flags in $capability$ will be set. But a SCSI
+\cdrom\ drive might be a caddy system, which can't load the tray, and
+hence for this drive the $cdrom_device_info$ struct will have set
+the $CDC_CLOSE_TRAY$ bit in $mask$.
+
+In the file \cdromc\ you will encounter many constructions of the type
+$$\it
+if\ (cdo\rightarrow capability \mathrel\& \mathord{\sim} cdi\rightarrow mask 
+   \mathrel{\&} CDC_<capability>) \ldots
+$$
+There is no $ioctl$ to set the mask\dots The reason is that
+I think it is better to control the {\em behavior\/} rather than the
+{\em capabilities}.
+
+\subsection{Options}
+
+A final flag register controls the {\em behavior\/} of the \cdrom\
+drives, in order to satisfy different users' wishes, hopefully
+independently of the ideas of the respective author who happened to
+have made the drive's support available to the \linux\ community. The
+current behavior options are:
+$$
+\halign{$#$\ \hfil&$/*$ \rm# $*/$\hfil\cr
+CDO_AUTO_CLOSE& try to close tray upon device $open()$\cr
+CDO_AUTO_EJECT& try to open tray on last device $close()$\cr
+CDO_USE_FFLAGS& use $file_pointer\rightarrow f_flags$ to indicate
+ purpose for $open()$\cr
+CDO_LOCK& try to lock door if device is opened\cr
+CDO_CHECK_TYPE& ensure disc type is data if opened for data\cr
+}
+$$
+
+The initial value of this register is $CDO_AUTO_CLOSE \mathrel|
+CDO_USE_FFLAGS \mathrel| CDO_LOCK$, reflecting my own view on user
+interface and software standards. Before you protest, there are two
+new $ioctl$s implemented in \cdromc, that allow you to control the
+behavior by software. These are:
+$$
+\halign{$#$\ \hfil&$/*$ \rm# $*/$\hfil\cr
+CDROM_SET_OPTIONS& set options specified in $(int)\ arg$\cr
+CDROM_CLEAR_OPTIONS& clear options specified in $(int)\ arg$\cr
+}
+$$
+One option needs some more explanation: $CDO_USE_FFLAGS$. In the next
+newsection we explain what the need for this option is.
+
+A software package {\tt setcd}, available from the Debian distribution
+and {\tt sunsite.unc.edu}, allows user level control of these flags. 
+
+\newsection{The need to know the purpose of opening the \cdrom\ device}
+
+Traditionally, Unix devices can be used in two different `modes',
+either by reading/writing to the device file, or by issuing
+controlling commands to the device, by the device's $ioctl()$
+call. The problem with \cdrom\ drives, is that they can be used for
+two entirely different purposes. One is to mount removable
+file systems, \cdrom s, the other is to play audio CD's. Audio commands
+are implemented entirely through $ioctl$s, presumably because the
+first implementation (SUN?) has been such. In principle there is
+nothing wrong with this, but a good control of the `CD player' demands
+that the device can {\em always\/} be opened in order to give the
+$ioctl$ commands, regardless of the state the drive is in. 
+
+On the other hand, when used as a removable-media disc drive (what the
+original purpose of \cdrom s is) we would like to make sure that the
+disc drive is ready for operation upon opening the device. In the old
+scheme, some \cdrom\ drivers don't do any integrity checking, resulting
+in a number of i/o errors reported by the VFS to the kernel when an
+attempt for mounting a \cdrom\ on an empty drive occurs. This is not a
+particularly elegant way to find out that there is no \cdrom\ inserted;
+it more-or-less looks like the old IBM-PC trying to read an empty floppy
+drive for a couple of seconds, after which the system complains it
+can't read from it. Nowadays we can {\em sense\/} the existence of a
+removable medium in a drive, and we believe we should exploit that
+fact. An integrity check on opening of the device, that verifies the
+availability of a \cdrom\ and its correct type (data), would be
+desirable.
+
+These two ways of using a \cdrom\ drive, principally for data and
+secondarily for playing audio discs, have different demands for the
+behavior of the $open()$ call. Audio use simply wants to open the
+device in order to get a file handle which is needed for issuing
+$ioctl$ commands, while data use wants to open for correct and
+reliable data transfer. The only way user programs can indicate what
+their {\em purpose\/} of opening the device is, is through the $flags$
+parameter (see {\tt {open(2)}}). For \cdrom\ devices, these flags aren't
+implemented (some drivers implement checking for write-related flags,
+but this is not strictly necessary if the device file has correct
+permission flags). Most option flags simply don't make sense to
+\cdrom\ devices: $O_CREAT$, $O_NOCTTY$, $O_TRUNC$, $O_APPEND$, and
+$O_SYNC$ have no meaning to a \cdrom. 
+
+We therefore propose to use the flag $O_NONBLOCK$ to indicate
+that the device is opened just for issuing $ioctl$
+commands. Strictly, the meaning of $O_NONBLOCK$ is that opening and
+subsequent calls to the device don't cause the calling process to
+wait. We could interpret this as ``don't wait until someone has
+inserted some valid data-\cdrom.'' Thus, our proposal of the
+implementation for the $open()$ call for \cdrom s is:
+\begin{itemize}
+\item If no other flags are set than $O_RDONLY$, the device is opened
+for data transfer, and the return value will be 0 only upon successful
+initialization of the transfer. The call may even induce some actions
+on the \cdrom, such as closing the tray.  
+\item If the option flag $O_NONBLOCK$ is set, opening will always be
+successful, unless the whole device doesn't exist. The drive will take
+no actions whatsoever. 
+\end{itemize}
+
+\subsection{And what about standards?}
+
+You might hesitate to accept this proposal as it comes from the
+\linux\ community, and not from some standardizing institute. What
+about SUN, SGI, HP and all those other Unix and hardware vendors?
+Well, these companies are in the lucky position that they generally
+control both the hardware and software of their supported products,
+and are large enough to set their own standard. They do not have to
+deal with a dozen or more different, competing hardware
+configurations.\footnote{Incidentally, I think that SUN's approach to
+mounting \cdrom s is very good in origin: under Solaris a
+volume-daemon automatically mounts a newly inserted \cdrom\ under {\tt
+{/cdrom/$<volume-name>$/}}. In my opinion they should have pushed this
+further and have {\em every\/} \cdrom\ on the local area network be
+mounted at the similar location, \ie, no matter in which particular
+machine you insert a \cdrom, it will always appear at the same
+position in the directory tree, on every system. When I wanted to
+implement such a user-program for \linux, I came across the
+differences in behavior of the various drivers, and the need for an
+$ioctl$ informing about media changes.}
+
+We believe that using $O_NONBLOCK$ to indicate that a device is being opened
+for $ioctl$ commands only can be easily introduced in the \linux\
+community. All the CD-player authors will have to be informed, we can
+even send in our own patches to the programs. The use of $O_NONBLOCK$
+has most likely no influence on the behavior of the CD-players on
+other operating systems than \linux. Finally, a user can always revert
+to old behavior by a call to $ioctl(file_descriptor, CDROM_CLEAR_OPTIONS,
+CDO_USE_FFLAGS)$. 
+
+\subsection{The preferred strategy of $open()$}
+
+The routines in \cdromc\ are designed in such a way that run-time
+configuration of the behavior of \cdrom\ devices (of {\em any\/} type)
+can be carried out, by the $CDROM_SET/CLEAR_OPTIONS$ $ioctls$. Thus, various
+modes of operation can be set:
+\begin{description}
+\item[$CDO_AUTO_CLOSE \mathrel| CDO_USE_FFLAGS \mathrel| CDO_LOCK$] This
+is the default setting. (With $CDO_CHECK_TYPE$ it will be better, in the
+future.) If the device is not yet opened by any other process, and if
+the device is being opened for data ($O_NONBLOCK$ is not set) and the
+tray is found to be open, an attempt to close the tray is made. Then,
+it is verified that a disc is in the drive and, if $CDO_CHECK_TYPE$ is
+set, that it contains tracks of type `data mode 1.' Only if all tests
+are passed is the return value zero. The door is locked to prevent file
+system corruption. If the drive is opened for audio ($O_NONBLOCK$ is
+set), no actions are taken and a value of 0 will be returned. 
+\item[$CDO_AUTO_CLOSE \mathrel| CDO_AUTO_EJECT \mathrel| CDO_LOCK$] This
+mimics the behavior of the current sbpcd-driver. The option flags are
+ignored, the tray is closed on the first open, if necessary. Similarly,
+the tray is opened on the last release, \ie, if a \cdrom\ is unmounted,
+it is automatically ejected, such that the user can replace it.
+\end{description} 
+We hope that these option can convince everybody (both driver
+maintainers and user program developers) to adopt the new \cdrom\
+driver scheme and option flag interpretation.
+
+\newsection{Description of routines in \cdromc}
+
+Only a few routines in \cdromc\ are exported to the drivers. In this
+new section we will discuss these, as well as the functions that `take
+over' the \cdrom\ interface to the kernel. The header file belonging
+to \cdromc\ is called \cdromh. Formerly, some of the contents of this
+file were placed in the file {\tt {ucdrom.h}}, but this file has now been
+merged back into \cdromh.
+
+\subsection{$Struct\ file_operations\ cdrom_fops$}
+
+The contents of this structure were described in section~\ref{cdrom.c}.
+A pointer to this structure is assigned to the $fops$ field
+of the $struct gendisk$.
+
+\subsection{$Int\ register_cdrom( struct\ cdrom_device_info\ * cdi)$}
+
+This function is used in about the same way one registers $cdrom_fops$
+with the kernel, the device operations and information structures,
+as described in section~\ref{cdrom.c}, should be registered with the
+\UCD:
+$$
+register_cdrom(\&<device>_info));
+$$
+This function returns zero upon success, and non-zero upon
+failure. The structure $<device>_info$ should have a pointer to the
+driver's $<device>_dops$, as in 
+$$
+\vbox{\halign{&$#$\hfil\cr
+struct\ &cdrom_device_info\ <device>_info = \{\cr
+& <device>_dops;\cr
+&\ldots\cr
+\}\cr
+}}$$
+Note that a driver must have one static structure, $<device>_dops$, while
+it may have as many structures $<device>_info$ as there are minor devices
+active. $Register_cdrom()$ builds a linked list from these. 
+
+\subsection{$Void\ unregister_cdrom(struct\ cdrom_device_info * cdi)$}
+
+Unregistering device $cdi$ with minor number $MINOR(cdi\to dev)$ removes
+the minor device from the list. If it was the last registered minor for
+the low-level driver, this disconnects the registered device-operation
+routines from the \cdrom\ interface. This function returns zero upon
+success, and non-zero upon failure.
+
+\subsection{$Int\ cdrom_open(struct\ inode * ip, struct\ file * fp)$}
+
+This function is not called directly by the low-level drivers, it is
+listed in the standard $cdrom_fops$. If the VFS opens a file, this
+function becomes active. A strategy is implemented in this routine,
+taking care of all capabilities and options that are set in the
+$cdrom_device_ops$ connected to the device. Then, the program flow is
+transferred to the device_dependent $open()$ call.
+
+\subsection{$Void\ cdrom_release(struct\ inode *ip, struct\ file
+*fp)$}
+
+This function implements the reverse-logic of $cdrom_open()$, and then
+calls the device-dependent $release()$ routine. When the use-count has
+reached 0, the allocated buffers are flushed by calls to $sync_dev(dev)$
+and $invalidate_buffers(dev)$.
+
+
+\subsection{$Int\ cdrom_ioctl(struct\ inode *ip, struct\ file *fp,
+unsigned\ int\ cmd, unsigned\ long\ arg)$}
+\label{cdrom-ioctl}
+
+This function handles all the standard $ioctl$ requests for \cdrom\
+devices in a uniform way. The different calls fall into three
+categories: $ioctl$s that can be directly implemented by device
+operations, ones that are routed through the call $audio_ioctl()$, and
+the remaining ones, that are presumable device-dependent. Generally, a
+negative return value indicates an error.
+
+\subsubsection{Directly implemented $ioctl$s}
+\label{ioctl-direct}
+
+The following `old' \cdrom-$ioctl$s are implemented by directly
+calling device-operations in $cdrom_device_ops$, if implemented and
+not masked:
+\begin{description}
+\item[CDROMMULTISESSION] Requests the last session on a \cdrom.
+\item[CDROMEJECT] Open tray. 
+\item[CDROMCLOSETRAY] Close tray.
+\item[CDROMEJECT_SW] If $arg\not=0$, set behavior to auto-close (close
+tray on first open) and auto-eject (eject on last release), otherwise
+set behavior to non-moving on $open()$ and $release()$ calls.
+\item[CDROM_GET_MCN] Get the Media Catalog Number from a CD.
+\end{description}
+
+\subsubsection{$Ioctl$s routed through $audio_ioctl()$}
+\label{ioctl-audio}
+
+The following set of $ioctl$s are all implemented through a call to
+the $cdrom_fops$ function $audio_ioctl()$. Memory checks and
+allocation are performed in $cdrom_ioctl()$, and also sanitization of
+address format ($CDROM_LBA$/$CDROM_MSF$) is done.
+\begin{description}
+\item[CDROMSUBCHNL] Get sub-channel data in argument $arg$ of type $struct\
+cdrom_subchnl *{}$.
+\item[CDROMREADTOCHDR] Read Table of Contents header, in $arg$ of type
+$struct\ cdrom_tochdr *{}$. 
+\item[CDROMREADTOCENTRY] Read a Table of Contents entry in $arg$ and
+specified by $arg$ of type $struct\ cdrom_tocentry *{}$.
+\item[CDROMPLAYMSF] Play audio fragment specified in Minute, Second,
+Frame format, delimited by $arg$ of type $struct\ cdrom_msf *{}$.
+\item[CDROMPLAYTRKIND] Play audio fragment in track-index format
+delimited by $arg$ of type $struct\ \penalty-1000 cdrom_ti *{}$.
+\item[CDROMVOLCTRL] Set volume specified by $arg$ of type $struct\
+cdrom_volctrl *{}$.
+\item[CDROMVOLREAD] Read volume into by $arg$ of type $struct\
+cdrom_volctrl *{}$.
+\item[CDROMSTART] Spin up disc.
+\item[CDROMSTOP] Stop playback of audio fragment.
+\item[CDROMPAUSE] Pause playback of audio fragment.
+\item[CDROMRESUME] Resume playing.
+\end{description}
+
+\subsubsection{New $ioctl$s in \cdromc}
+
+The following $ioctl$s have been introduced to allow user programs to
+control the behavior of individual \cdrom\ devices. New $ioctl$
+commands can be identified by the underscores in their names.
+\begin{description}
+\item[CDROM_SET_OPTIONS] Set options specified by $arg$. Returns the
+option flag register after modification. Use  $arg = \rm0$ for reading
+the current flags.
+\item[CDROM_CLEAR_OPTIONS] Clear options specified by $arg$. Returns
+  the option flag register after modification.
+\item[CDROM_SELECT_SPEED] Select head-rate speed of disc specified as
+  by $arg$ in units of standard cdrom speed (176\,kB/sec raw data or
+  150\,kB/sec file system data). The value 0 means `auto-select', \ie,
+  play audio discs at real time and data discs at maximum speed. The value
+  $arg$ is checked against the maximum head rate of the drive found in the
+  $cdrom_dops$.
+\item[CDROM_SELECT_DISC] Select disc numbered $arg$ from a juke-box.
+  First disc is numbered 0. The number $arg$ is checked against the
+  maximum number of discs in the juke-box found in the $cdrom_dops$.
+\item[CDROM_MEDIA_CHANGED] Returns 1 if a disc has been changed since
+  the last call. Note that calls to $cdrom_media_changed$ by the VFS
+  are treated by an independent queue, so both mechanisms will detect
+  a media change once. For juke-boxes, an extra argument $arg$
+  specifies the slot for which the information is given. The special
+  value $CDSL_CURRENT$ requests that information about the currently
+  selected slot be returned.
+\item[CDROM_DRIVE_STATUS] Returns the status of the drive by a call to
+  $drive_status()$. Return values are defined in section~\ref{drive
+   status}. Note that this call doesn't return information on the
+  current playing activity of the drive; this can be polled through an
+  $ioctl$ call to $CDROMSUBCHNL$. For juke-boxes, an extra argument
+  $arg$ specifies the slot for which (possibly limited) information is
+  given. The special value $CDSL_CURRENT$ requests that information
+  about the currently selected slot be returned.
+\item[CDROM_DISC_STATUS] Returns the type of the disc currently in the
+  drive.  It should be viewed as a complement to $CDROM_DRIVE_STATUS$.
+  This $ioctl$ can provide \emph {some} information about the current
+  disc that is inserted in the drive.  This functionality used to be
+  implemented in the low level drivers, but is now carried out
+  entirely in \UCD.
+  
+  The history of development of the CD's use as a carrier medium for
+  various digital information has lead to many different disc types.
+  This $ioctl$ is useful only in the case that CDs have \emph {only
+    one} type of data on them.  While this is often the case, it is
+  also very common for CDs to have some tracks with data, and some
+  tracks with audio.  Because this is an existing interface, rather
+  than fixing this interface by changing the assumptions it was made
+  under, thereby breaking all user applications that use this
+  function, the \UCD\ implements this $ioctl$ as follows: If the CD in
+  question has audio tracks on it, and it has absolutely no CD-I, XA,
+  or data tracks on it, it will be reported as $CDS_AUDIO$.  If it has
+  both audio and data tracks, it will return $CDS_MIXED$.  If there
+  are no audio tracks on the disc, and if the CD in question has any
+  CD-I tracks on it, it will be reported as $CDS_XA_2_2$.  Failing
+  that, if the CD in question has any XA tracks on it, it will be
+  reported as $CDS_XA_2_1$.  Finally, if the CD in question has any
+  data tracks on it, it will be reported as a data CD ($CDS_DATA_1$).
+
+  This $ioctl$ can return:
+  $$
+  \halign{$#$\ \hfil&$/*$ \rm# $*/$\hfil\cr
+    CDS_NO_INFO& no information available\cr
+    CDS_NO_DISC& no disc is inserted, or tray is opened\cr
+    CDS_AUDIO& Audio disc (2352 audio bytes/frame)\cr
+    CDS_DATA_1& data disc, mode 1 (2048 user bytes/frame)\cr
+    CDS_XA_2_1& mixed data (XA), mode 2, form 1 (2048 user bytes)\cr
+    CDS_XA_2_2& mixed data (XA), mode 2, form 1 (2324  user bytes)\cr
+    CDS_MIXED& mixed audio/data disc\cr
+    }
+  $$
+  For some information concerning frame layout of the various disc
+  types, see a recent version of \cdromh.
+
+\item[CDROM_CHANGER_NSLOTS] Returns the number of slots in a
+  juke-box. 
+\item[CDROMRESET] Reset the drive. 
+\item[CDROM_GET_CAPABILITY] Returns the $capability$ flags for the
+  drive. Refer to section \ref{capability} for more information on
+  these flags.
+\item[CDROM_LOCKDOOR] Locks the door of the drive. $arg == \rm0$
+  unlocks the door, any other value locks it.
+\item[CDROM_DEBUG] Turns on debugging info. Only root is allowed
+  to do this. Same semantics as CDROM_LOCKDOOR.
+\end{description}
+
+\subsubsection{Device dependent $ioctl$s}
+
+Finally, all other $ioctl$s are passed to the function $dev_ioctl()$,
+if implemented. No memory allocation or verification is carried out. 
+
+\newsection{How to update your driver}
+
+\begin{enumerate}
+\item Make a backup of your current driver. 
+\item Get hold of the files \cdromc\ and \cdromh, they should be in
+  the directory tree that came with this documentation.
+\item Make sure you include \cdromh.
+\item Change the 3rd argument of $register_blkdev$ from
+$\&<your-drive>_fops$ to $\&cdrom_fops$. 
+\item Just after that line, add the following to register with the \UCD:
+  $$register_cdrom(\&<your-drive>_info);$$
+  Similarly, add a call to $unregister_cdrom()$ at the appropriate place.
+\item Copy an example of the device-operations $struct$ to your
+  source, \eg, from {\tt {cm206.c}} $cm206_dops$, and change all
+  entries to names corresponding to your driver, or names you just
+  happen to like. If your driver doesn't support a certain function,
+  make the entry $NULL$. At the entry $capability$ you should list all
+  capabilities your driver currently supports. If your driver
+  has a capability that is not listed, please send me a message.
+\item Copy the $cdrom_device_info$ declaration from the same example
+  driver, and modify the entries according to your needs. If your
+  driver dynamically determines the capabilities of the hardware, this
+  structure should also be declared dynamically. 
+\item Implement all functions in your $<device>_dops$ structure,
+  according to prototypes listed in \cdromh, and specifications given
+  in section~\ref{cdrom.c}. Most likely you have already implemented
+  the code in a large part, and you will almost certainly need to adapt the
+  prototype and return values.
+\item Rename your $<device>_ioctl()$ function to $audio_ioctl$ and
+  change the prototype a little. Remove entries listed in the first
+  part in section~\ref{cdrom-ioctl}, if your code was OK, these are
+  just calls to the routines you adapted in the previous step.
+\item You may remove all remaining memory checking code in the
+  $audio_ioctl()$ function that deals with audio commands (these are
+  listed in the second part of section~\ref{cdrom-ioctl}). There is no
+  need for memory allocation either, so most $case$s in the $switch$
+  statement look similar to:
+  $$
+  case\ CDROMREADTOCENTRY\colon get_toc_entry\bigl((struct\ 
+  cdrom_tocentry *{})\ arg\bigr);
+  $$
+\item All remaining $ioctl$ cases must be moved to a separate
+  function, $<device>_ioctl$, the device-dependent $ioctl$s. Note that
+  memory checking and allocation must be kept in this code!
+\item Change the prototypes of $<device>_open()$ and
+  $<device>_release()$, and remove any strategic code (\ie, tray
+  movement, door locking, etc.).
+\item Try to recompile the drivers. We advise you to use modules, both
+  for {\tt {cdrom.o}} and your driver, as debugging is much easier this
+  way.
+\end{enumerate} 
+
+\newsection{Thanks}
+
+Thanks to all the people involved.  First, Erik Andersen, who has
+taken over the torch in maintaining \cdromc\ and integrating much
+\cdrom-related code in the 2.1-kernel.  Thanks to Scott Snyder and
+Gerd Knorr, who were the first to implement this interface for SCSI
+and IDE-CD drivers and added many ideas for extension of the data
+structures relative to kernel~2.0.  Further thanks to Heiko Ei{\ss}feldt,
+Thomas Quinot, Jon Tombs, Ken Pizzini, Eberhard M\"onkeberg and Andrew
+Kroll, the \linux\ \cdrom\ device driver developers who were kind
+enough to give suggestions and criticisms during the writing. Finally
+of course, I want to thank Linus Torvalds for making this possible in
+the first place.
+
+\vfill
+$ \version\ $
+\eject
+\end{document}
diff --git a/Documentation/cdrom/ide-cd b/Documentation/cdrom/ide-cd
new file mode 100644
index 000000000..a5f2a7f1f
--- /dev/null
+++ b/Documentation/cdrom/ide-cd
@@ -0,0 +1,534 @@
+IDE-CD driver documentation
+Originally by scott snyder  <snyder@fnald0.fnal.gov> (19 May 1996)
+Carrying on the torch is: Erik Andersen <andersee@debian.org>
+New maintainers (19 Oct 1998): Jens Axboe <axboe@image.dk>
+
+1. Introduction
+---------------
+
+The ide-cd driver should work with all ATAPI ver 1.2 to ATAPI 2.6 compliant 
+CDROM drives which attach to an IDE interface.  Note that some CDROM vendors
+(including Mitsumi, Sony, Creative, Aztech, and Goldstar) have made
+both ATAPI-compliant drives and drives which use a proprietary
+interface.  If your drive uses one of those proprietary interfaces,
+this driver will not work with it (but one of the other CDROM drivers
+probably will).  This driver will not work with `ATAPI' drives which
+attach to the parallel port.  In addition, there is at least one drive
+(CyCDROM CR520ie) which attaches to the IDE port but is not ATAPI;
+this driver will not work with drives like that either (but see the
+aztcd driver).
+
+This driver provides the following features:
+
+ - Reading from data tracks, and mounting ISO 9660 filesystems.
+
+ - Playing audio tracks.  Most of the CDROM player programs floating
+   around should work; I usually use Workman.
+
+ - Multisession support.
+
+ - On drives which support it, reading digital audio data directly
+   from audio tracks.  The program cdda2wav can be used for this.
+   Note, however, that only some drives actually support this.
+
+ - There is now support for CDROM changers which comply with the 
+   ATAPI 2.6 draft standard (such as the NEC CDR-251).  This additional
+   functionality includes a function call to query which slot is the
+   currently selected slot, a function call to query which slots contain
+   CDs, etc. A sample program which demonstrates this functionality is
+   appended to the end of this file.  The Sanyo 3-disc changer
+   (which does not conform to the standard) is also now supported.
+   Please note the driver refers to the first CD as slot # 0.
+
+
+2. Installation
+---------------
+
+0. The ide-cd relies on the ide disk driver.  See
+   Documentation/ide/ide.txt for up-to-date information on the ide
+   driver.
+
+1. Make sure that the ide and ide-cd drivers are compiled into the
+   kernel you're using.  When configuring the kernel, in the section 
+   entitled "Floppy, IDE, and other block devices", say either `Y' 
+   (which will compile the support directly into the kernel) or `M'
+   (to compile support as a module which can be loaded and unloaded)
+   to the options: 
+
+      ATA/ATAPI/MFM/RLL support
+      Include IDE/ATAPI CDROM support
+
+   Depending on what type of IDE interface you have, you may need to
+   specify additional configuration options.  See
+   Documentation/ide/ide.txt.
+
+2. You should also ensure that the iso9660 filesystem is either
+   compiled into the kernel or available as a loadable module.  You
+   can see if a filesystem is known to the kernel by catting
+   /proc/filesystems.
+
+3. The CDROM drive should be connected to the host on an IDE
+   interface.  Each interface on a system is defined by an I/O port
+   address and an IRQ number, the standard assignments being
+   0x1f0 and 14 for the primary interface and 0x170 and 15 for the
+   secondary interface.  Each interface can control up to two devices,
+   where each device can be a hard drive, a CDROM drive, a floppy drive, 
+   or a tape drive.  The two devices on an interface are called `master'
+   and `slave'; this is usually selectable via a jumper on the drive.
+
+   Linux names these devices as follows.  The master and slave devices
+   on the primary IDE interface are called `hda' and `hdb',
+   respectively.  The drives on the secondary interface are called
+   `hdc' and `hdd'.  (Interfaces at other locations get other letters
+   in the third position; see Documentation/ide/ide.txt.)
+
+   If you want your CDROM drive to be found automatically by the
+   driver, you should make sure your IDE interface uses either the
+   primary or secondary addresses mentioned above.  In addition, if
+   the CDROM drive is the only device on the IDE interface, it should
+   be jumpered as `master'.  (If for some reason you cannot configure
+   your system in this manner, you can probably still use the driver.
+   You may have to pass extra configuration information to the kernel
+   when you boot, however.  See Documentation/ide/ide.txt for more
+   information.)
+
+4. Boot the system.  If the drive is recognized, you should see a
+   message which looks like
+
+     hdb: NEC CD-ROM DRIVE:260, ATAPI CDROM drive
+
+   If you do not see this, see section 5 below.
+
+5. You may want to create a symbolic link /dev/cdrom pointing to the
+   actual device.  You can do this with the command
+
+     ln -s  /dev/hdX  /dev/cdrom
+
+   where X should be replaced by the letter indicating where your
+   drive is installed.
+
+6. You should be able to see any error messages from the driver with
+   the `dmesg' command.
+
+
+3. Basic usage
+--------------
+
+An ISO 9660 CDROM can be mounted by putting the disc in the drive and 
+typing (as root)
+
+  mount -t iso9660 /dev/cdrom /mnt/cdrom
+
+where it is assumed that /dev/cdrom is a link pointing to the actual
+device (as described in step 5 of the last section) and /mnt/cdrom is
+an empty directory.  You should now be able to see the contents of the
+CDROM under the /mnt/cdrom directory.  If you want to eject the CDROM,
+you must first dismount it with a command like
+
+  umount /mnt/cdrom
+
+Note that audio CDs cannot be mounted.
+
+Some distributions set up /etc/fstab to always try to mount a CDROM
+filesystem on bootup.  It is not required to mount the CDROM in this
+manner, though, and it may be a nuisance if you change CDROMs often.
+You should feel free to remove the cdrom line from /etc/fstab and
+mount CDROMs manually if that suits you better.
+
+Multisession and photocd discs should work with no special handling.
+The hpcdtoppm package (ftp.gwdg.de:/pub/linux/hpcdtoppm/) may be
+useful for reading photocds.
+
+To play an audio CD, you should first unmount and remove any data
+CDROM.  Any of the CDROM player programs should then work (workman,
+workbone, cdplayer, etc.).
+
+On a few drives, you can read digital audio directly using a program
+such as cdda2wav.  The only types of drive which I've heard support
+this are Sony and Toshiba drives.  You will get errors if you try to
+use this function on a drive which does not support it.
+
+For supported changers, you can use the `cdchange' program (appended to
+the end of this file) to switch between changer slots.  Note that the
+drive should be unmounted before attempting this.  The program takes
+two arguments:  the CDROM device, and the slot number to which you wish
+to change.  If the slot number is -1, the drive is unloaded.
+
+
+4. Common problems
+------------------
+
+This section discusses some common problems encountered when trying to
+use the driver, and some possible solutions.  Note that if you are
+experiencing problems, you should probably also review
+Documentation/ide/ide.txt for current information about the underlying
+IDE support code.  Some of these items apply only to earlier versions
+of the driver, but are mentioned here for completeness.
+
+In most cases, you should probably check with `dmesg' for any errors
+from the driver.
+
+a. Drive is not detected during booting.
+
+   - Review the configuration instructions above and in
+     Documentation/ide/ide.txt, and check how your hardware is
+     configured.
+
+   - If your drive is the only device on an IDE interface, it should
+     be jumpered as master, if at all possible.
+
+   - If your IDE interface is not at the standard addresses of 0x170
+     or 0x1f0, you'll need to explicitly inform the driver using a
+     lilo option.  See Documentation/ide/ide.txt.  (This feature was
+     added around kernel version 1.3.30.)
+
+   - If the autoprobing is not finding your drive, you can tell the
+     driver to assume that one exists by using a lilo option of the
+     form `hdX=cdrom', where X is the drive letter corresponding to
+     where your drive is installed.  Note that if you do this and you 
+     see a boot message like
+
+       hdX: ATAPI cdrom (?)
+
+     this does _not_ mean that the driver has successfully detected
+     the drive; rather, it means that the driver has not detected a
+     drive, but is assuming there's one there anyway because you told
+     it so.  If you actually try to do I/O to a drive defined at a
+     nonexistent or nonresponding I/O address, you'll probably get
+     errors with a status value of 0xff.
+
+   - Some IDE adapters require a nonstandard initialization sequence
+     before they'll function properly.  (If this is the case, there
+     will often be a separate MS-DOS driver just for the controller.)
+     IDE interfaces on sound cards often fall into this category.
+
+     Support for some interfaces needing extra initialization is
+     provided in later 1.3.x kernels.  You may need to turn on
+     additional kernel configuration options to get them to work;
+     see Documentation/ide/ide.txt.
+
+     Even if support is not available for your interface, you may be
+     able to get it to work with the following procedure.  First boot
+     MS-DOS and load the appropriate drivers.  Then warm-boot linux
+     (i.e., without powering off).  If this works, it can be automated
+     by running loadlin from the MS-DOS autoexec.
+
+
+b. Timeout/IRQ errors.
+
+  - If you always get timeout errors, interrupts from the drive are
+    probably not making it to the host.
+
+  - IRQ problems may also be indicated by the message
+    `IRQ probe failed (<n>)' while booting.  If <n> is zero, that
+    means that the system did not see an interrupt from the drive when
+    it was expecting one (on any feasible IRQ).  If <n> is negative,
+    that means the system saw interrupts on multiple IRQ lines, when
+    it was expecting to receive just one from the CDROM drive.
+
+  - Double-check your hardware configuration to make sure that the IRQ
+    number of your IDE interface matches what the driver expects.
+    (The usual assignments are 14 for the primary (0x1f0) interface
+    and 15 for the secondary (0x170) interface.)  Also be sure that
+    you don't have some other hardware which might be conflicting with
+    the IRQ you're using.  Also check the BIOS setup for your system;
+    some have the ability to disable individual IRQ levels, and I've
+    had one report of a system which was shipped with IRQ 15 disabled
+    by default.
+
+  - Note that many MS-DOS CDROM drivers will still function even if
+    there are hardware problems with the interrupt setup; they
+    apparently don't use interrupts.
+
+  - If you own a Pioneer DR-A24X, you _will_ get nasty error messages 
+    on boot such as "irq timeout: status=0x50 { DriveReady SeekComplete }"
+    The Pioneer DR-A24X CDROM drives are fairly popular these days.
+    Unfortunately, these drives seem to become very confused when we perform
+    the standard Linux ATA disk drive probe. If you own one of these drives,
+    you can bypass the ATA probing which confuses these CDROM drives, by 
+    adding `append="hdX=noprobe hdX=cdrom"' to your lilo.conf file and running 
+    lilo (again where X is the drive letter corresponding to where your drive 
+    is installed.)
+    
+c. System hangups.
+
+  - If the system locks up when you try to access the CDROM, the most
+    likely cause is that you have a buggy IDE adapter which doesn't
+    properly handle simultaneous transactions on multiple interfaces.
+    The most notorious of these is the CMD640B chip.  This problem can
+    be worked around by specifying the `serialize' option when
+    booting.  Recent kernels should be able to detect the need for
+    this automatically in most cases, but the detection is not
+    foolproof.  See Documentation/ide/ide.txt for more information
+    about the `serialize' option and the CMD640B.
+
+  - Note that many MS-DOS CDROM drivers will work with such buggy
+    hardware, apparently because they never attempt to overlap CDROM
+    operations with other disk activity.
+
+
+d. Can't mount a CDROM.
+
+  - If you get errors from mount, it may help to check `dmesg' to see
+    if there are any more specific errors from the driver or from the
+    filesystem.
+
+  - Make sure there's a CDROM loaded in the drive, and that's it's an
+    ISO 9660 disc.  You can't mount an audio CD.
+
+  - With the CDROM in the drive and unmounted, try something like
+
+      cat /dev/cdrom | od | more
+
+    If you see a dump, then the drive and driver are probably working
+    OK, and the problem is at the filesystem level (i.e., the CDROM is
+    not ISO 9660 or has errors in the filesystem structure).
+
+  - If you see `not a block device' errors, check that the definitions
+    of the device special files are correct.  They should be as
+    follows:
+
+      brw-rw----   1 root     disk       3,   0 Nov 11 18:48 /dev/hda
+      brw-rw----   1 root     disk       3,  64 Nov 11 18:48 /dev/hdb
+      brw-rw----   1 root     disk      22,   0 Nov 11 18:48 /dev/hdc
+      brw-rw----   1 root     disk      22,  64 Nov 11 18:48 /dev/hdd
+
+    Some early Slackware releases had these defined incorrectly.  If
+    these are wrong, you can remake them by running the script
+    scripts/MAKEDEV.ide.  (You may have to make it executable
+    with chmod first.)
+
+    If you have a /dev/cdrom symbolic link, check that it is pointing
+    to the correct device file.
+
+    If you hear people talking of the devices `hd1a' and `hd1b', these
+    were old names for what are now called hdc and hdd.  Those names
+    should be considered obsolete.
+
+  - If mount is complaining that the iso9660 filesystem is not
+    available, but you know it is (check /proc/filesystems), you
+    probably need a newer version of mount.  Early versions would not
+    always give meaningful error messages.
+
+
+e. Directory listings are unpredictably truncated, and `dmesg' shows
+   `buffer botch' error messages from the driver.
+
+  - There was a bug in the version of the driver in 1.2.x kernels
+    which could cause this.  It was fixed in 1.3.0.  If you can't
+    upgrade, you can probably work around the problem by specifying a
+    blocksize of 2048 when mounting.  (Note that you won't be able to
+    directly execute binaries off the CDROM in that case.)
+
+    If you see this in kernels later than 1.3.0, please report it as a
+    bug.
+
+
+f. Data corruption.
+
+  - Random data corruption was occasionally observed with the Hitachi
+    CDR-7730 CDROM. If you experience data corruption, using "hdx=slow"
+    as a command line parameter may work around the problem, at the
+    expense of low system performance.
+
+
+5. cdchange.c
+-------------
+
+/*
+ * cdchange.c  [-v]  <device>  [<slot>]
+ *
+ * This loads a CDROM from a specified slot in a changer, and displays 
+ * information about the changer status.  The drive should be unmounted before 
+ * using this program.
+ *
+ * Changer information is displayed if either the -v flag is specified
+ * or no slot was specified.
+ *
+ * Based on code originally from Gerhard Zuber <zuber@berlin.snafu.de>.
+ * Changer status information, and rewrite for the new Uniform CDROM driver
+ * interface by Erik Andersen <andersee@debian.org>.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/cdrom.h>
+
+
+int
+main (int argc, char **argv)
+{
+	char *program;
+	char *device;
+	int fd;           /* file descriptor for CD-ROM device */
+	int status;       /* return status for system calls */
+	int verbose = 0;
+	int slot=-1, x_slot;
+	int total_slots_available;
+
+	program = argv[0];
+
+	++argv;
+	--argc;
+
+	if (argc < 1 || argc > 3) {
+		fprintf (stderr, "usage: %s [-v] <device> [<slot>]\n",
+			 program);
+		fprintf (stderr, "       Slots are numbered 1 -- n.\n");
+		exit (1);
+	}
+ 
+       if (strcmp (argv[0], "-v") == 0) {
+                verbose = 1;
+                ++argv;
+                --argc;
+        }
+ 
+	device = argv[0];
+ 
+	if (argc == 2)
+		slot = atoi (argv[1]) - 1;
+
+	/* open device */ 
+	fd = open(device, O_RDONLY | O_NONBLOCK);
+	if (fd < 0) {
+		fprintf (stderr, "%s: open failed for `%s': %s\n",
+			 program, device, strerror (errno));
+		exit (1);
+	}
+
+	/* Check CD player status */ 
+	total_slots_available = ioctl (fd, CDROM_CHANGER_NSLOTS);
+	if (total_slots_available <= 1 ) {
+		fprintf (stderr, "%s: Device `%s' is not an ATAPI "
+			"compliant CD changer.\n", program, device);
+		exit (1);
+	}
+
+	if (slot >= 0) {
+		if (slot >= total_slots_available) {
+			fprintf (stderr, "Bad slot number.  "
+				 "Should be 1 -- %d.\n",
+				 total_slots_available);
+			exit (1);
+		}
+
+		/* load */ 
+		slot=ioctl (fd, CDROM_SELECT_DISC, slot);
+		if (slot<0) {
+			fflush(stdout);
+				perror ("CDROM_SELECT_DISC ");
+			exit(1);
+		}
+	}
+
+	if (slot < 0 || verbose) {
+
+		status=ioctl (fd, CDROM_SELECT_DISC, CDSL_CURRENT);
+		if (status<0) {
+			fflush(stdout);
+			perror (" CDROM_SELECT_DISC");
+			exit(1);
+		}
+		slot=status;
+
+		printf ("Current slot: %d\n", slot+1);
+		printf ("Total slots available: %d\n",
+			total_slots_available);
+
+		printf ("Drive status: ");
+                status = ioctl (fd, CDROM_DRIVE_STATUS, CDSL_CURRENT);
+                if (status<0) {
+                  perror(" CDROM_DRIVE_STATUS");
+                } else switch(status) {
+		case CDS_DISC_OK:
+			printf ("Ready.\n");
+			break;
+		case CDS_TRAY_OPEN:
+			printf ("Tray Open.\n");
+			break;
+		case CDS_DRIVE_NOT_READY:
+			printf ("Drive Not Ready.\n");
+			break;
+		default:
+			printf ("This Should not happen!\n");
+			break;
+		}
+
+		for (x_slot=0; x_slot<total_slots_available; x_slot++) {
+			printf ("Slot %2d: ", x_slot+1);
+             		status = ioctl (fd, CDROM_DRIVE_STATUS, x_slot);
+             		if (status<0) {
+             		     perror(" CDROM_DRIVE_STATUS");
+             		} else switch(status) {
+			case CDS_DISC_OK:
+				printf ("Disc present.");
+				break;
+			case CDS_NO_DISC: 
+				printf ("Empty slot.");
+				break;
+			case CDS_TRAY_OPEN:
+				printf ("CD-ROM tray open.\n");
+				break;
+			case CDS_DRIVE_NOT_READY:
+				printf ("CD-ROM drive not ready.\n");
+				break;
+			case CDS_NO_INFO:
+				printf ("No Information available.");
+				break;
+			default:
+				printf ("This Should not happen!\n");
+				break;
+			}
+		  if (slot == x_slot) {
+                  status = ioctl (fd, CDROM_DISC_STATUS);
+                  if (status<0) {
+			perror(" CDROM_DISC_STATUS");
+                  }
+		  switch (status) {
+			case CDS_AUDIO:
+				printf ("\tAudio disc.\t");
+				break;
+			case CDS_DATA_1:
+			case CDS_DATA_2:
+				printf ("\tData disc type %d.\t", status-CDS_DATA_1+1);
+				break;
+			case CDS_XA_2_1:
+			case CDS_XA_2_2:
+				printf ("\tXA data disc type %d.\t", status-CDS_XA_2_1+1);
+				break;
+			default:
+				printf ("\tUnknown disc type 0x%x!\t", status);
+				break;
+			}
+			}
+                  	status = ioctl (fd, CDROM_MEDIA_CHANGED, x_slot);
+                  	if (status<0) {
+				perror(" CDROM_MEDIA_CHANGED");
+                  	}
+		  	switch (status) {
+			case 1:
+				printf ("Changed.\n");
+				break;
+			default:
+				printf ("\n");
+				break;
+			}
+		}
+	}
+
+	/* close device */
+	status = close (fd);
+	if (status != 0) {
+		fprintf (stderr, "%s: close failed for `%s': %s\n",
+			 program, device, strerror (errno));
+		exit (1);
+	}
+ 
+	exit (0);
+}
diff --git a/Documentation/cdrom/packet-writing.txt b/Documentation/cdrom/packet-writing.txt
new file mode 100644
index 000000000..2834170d8
--- /dev/null
+++ b/Documentation/cdrom/packet-writing.txt
@@ -0,0 +1,132 @@
+Getting started quick
+---------------------
+
+- Select packet support in the block device section and UDF support in
+  the file system section.
+
+- Compile and install kernel and modules, reboot.
+
+- You need the udftools package (pktsetup, mkudffs, cdrwtool).
+  Download from http://sourceforge.net/projects/linux-udf/
+
+- Grab a new CD-RW disc and format it (assuming CD-RW is hdc, substitute
+  as appropriate):
+	# cdrwtool -d /dev/hdc -q
+
+- Setup your writer
+	# pktsetup dev_name /dev/hdc
+
+- Now you can mount /dev/pktcdvd/dev_name and copy files to it. Enjoy!
+	# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
+
+
+Packet writing for DVD-RW media
+-------------------------------
+
+DVD-RW discs can be written to much like CD-RW discs if they are in
+the so called "restricted overwrite" mode. To put a disc in restricted
+overwrite mode, run:
+
+	# dvd+rw-format /dev/hdc
+
+You can then use the disc the same way you would use a CD-RW disc:
+
+	# pktsetup dev_name /dev/hdc
+	# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
+
+
+Packet writing for DVD+RW media
+-------------------------------
+
+According to the DVD+RW specification, a drive supporting DVD+RW discs
+shall implement "true random writes with 2KB granularity", which means
+that it should be possible to put any filesystem with a block size >=
+2KB on such a disc. For example, it should be possible to do:
+
+	# dvd+rw-format /dev/hdc   (only needed if the disc has never
+	                            been formatted)
+	# mkudffs /dev/hdc
+	# mount /dev/hdc /cdrom -t udf -o rw,noatime
+
+However, some drives don't follow the specification and expect the
+host to perform aligned writes at 32KB boundaries. Other drives do
+follow the specification, but suffer bad performance problems if the
+writes are not 32KB aligned.
+
+Both problems can be solved by using the pktcdvd driver, which always
+generates aligned writes.
+
+	# dvd+rw-format /dev/hdc
+	# pktsetup dev_name /dev/hdc
+	# mkudffs /dev/pktcdvd/dev_name
+	# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
+
+
+Packet writing for DVD-RAM media
+--------------------------------
+
+DVD-RAM discs are random writable, so using the pktcdvd driver is not
+necessary. However, using the pktcdvd driver can improve performance
+in the same way it does for DVD+RW media.
+
+
+Notes
+-----
+
+- CD-RW media can usually not be overwritten more than about 1000
+  times, so to avoid unnecessary wear on the media, you should always
+  use the noatime mount option.
+
+- Defect management (ie automatic remapping of bad sectors) has not
+  been implemented yet, so you are likely to get at least some
+  filesystem corruption if the disc wears out.
+
+- Since the pktcdvd driver makes the disc appear as a regular block
+  device with a 2KB block size, you can put any filesystem you like on
+  the disc. For example, run:
+
+	# /sbin/mke2fs /dev/pktcdvd/dev_name
+
+  to create an ext2 filesystem on the disc.
+
+
+Using the pktcdvd sysfs interface
+---------------------------------
+
+Since Linux 2.6.20, the pktcdvd module has a sysfs interface
+and can be controlled by it. For example the "pktcdvd" tool uses
+this interface. (see http://tom.ist-im-web.de/download/pktcdvd )
+
+"pktcdvd" works similar to "pktsetup", e.g.:
+
+	# pktcdvd -a dev_name /dev/hdc
+	# mkudffs /dev/pktcdvd/dev_name
+	# mount -t udf -o rw,noatime /dev/pktcdvd/dev_name /dvdram
+	# cp files /dvdram
+	# umount /dvdram
+	# pktcdvd -r dev_name
+
+
+For a description of the sysfs interface look into the file:
+
+  Documentation/ABI/testing/sysfs-class-pktcdvd
+
+
+Using the pktcdvd debugfs interface
+-----------------------------------
+
+To read pktcdvd device infos in human readable form, do:
+
+	# cat /sys/kernel/debug/pktcdvd/pktcdvd[0-7]/info
+
+For a description of the debugfs interface look into the file:
+
+  Documentation/ABI/testing/debugfs-pktcdvd
+
+
+
+Links
+-----
+
+See http://fy.chalmers.se/~appro/linux/DVD+RW/ for more information
+about DVD writing.