Adding upstream version 6.6.15.upstream/6.6.15

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

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+===================================
+Command Line Options for Linux/m68k
+===================================
+
+Last Update: 2 May 1999
+
+Linux/m68k version: 2.2.6
+
+Author: Roman.Hodek@informatik.uni-erlangen.de (Roman Hodek)
+
+Update: jds@kom.auc.dk (Jes Sorensen) and faq@linux-m68k.org (Chris Lawrence)
+
+0) Introduction
+===============
+
+Often I've been asked which command line options the Linux/m68k
+kernel understands, or how the exact syntax for the ... option is, or
+... about the option ... . I hope, this document supplies all the
+answers...
+
+Note that some options might be outdated, their descriptions being
+incomplete or missing. Please update the information and send in the
+patches.
+
+
+1) Overview of the Kernel's Option Processing
+=============================================
+
+The kernel knows three kinds of options on its command line:
+
+  1) kernel options
+  2) environment settings
+  3) arguments for init
+
+To which of these classes an argument belongs is determined as
+follows: If the option is known to the kernel itself, i.e. if the name
+(the part before the '=') or, in some cases, the whole argument string
+is known to the kernel, it belongs to class 1. Otherwise, if the
+argument contains an '=', it is of class 2, and the definition is put
+into init's environment. All other arguments are passed to init as
+command line options.
+
+This document describes the valid kernel options for Linux/m68k in
+the version mentioned at the start of this file. Later revisions may
+add new such options, and some may be missing in older versions.
+
+In general, the value (the part after the '=') of an option is a
+list of values separated by commas. The interpretation of these values
+is up to the driver that "owns" the option. This association of
+options with drivers is also the reason that some are further
+subdivided.
+
+
+2) General Kernel Options
+=========================
+
+2.1) root=
+----------
+
+:Syntax: root=/dev/<device>
+:or:     root=<hex_number>
+
+This tells the kernel which device it should mount as the root
+filesystem. The device must be a block device with a valid filesystem
+on it.
+
+The first syntax gives the device by name. These names are converted
+into a major/minor number internally in the kernel in an unusual way.
+Normally, this "conversion" is done by the device files in /dev, but
+this isn't possible here, because the root filesystem (with /dev)
+isn't mounted yet... So the kernel parses the name itself, with some
+hardcoded name to number mappings. The name must always be a
+combination of two or three letters, followed by a decimal number.
+Valid names are::
+
+  /dev/ram: -> 0x0100 (initial ramdisk)
+  /dev/hda: -> 0x0300 (first IDE disk)
+  /dev/hdb: -> 0x0340 (second IDE disk)
+  /dev/sda: -> 0x0800 (first SCSI disk)
+  /dev/sdb: -> 0x0810 (second SCSI disk)
+  /dev/sdc: -> 0x0820 (third SCSI disk)
+  /dev/sdd: -> 0x0830 (forth SCSI disk)
+  /dev/sde: -> 0x0840 (fifth SCSI disk)
+  /dev/fd : -> 0x0200 (floppy disk)
+
+The name must be followed by a decimal number, that stands for the
+partition number. Internally, the value of the number is just
+added to the device number mentioned in the table above. The
+exceptions are /dev/ram and /dev/fd, where /dev/ram refers to an
+initial ramdisk loaded by your bootstrap program (please consult the
+instructions for your bootstrap program to find out how to load an
+initial ramdisk). As of kernel version 2.0.18 you must specify
+/dev/ram as the root device if you want to boot from an initial
+ramdisk. For the floppy devices, /dev/fd, the number stands for the
+floppy drive number (there are no partitions on floppy disks). I.e.,
+/dev/fd0 stands for the first drive, /dev/fd1 for the second, and so
+on. Since the number is just added, you can also force the disk format
+by adding a number greater than 3. If you look into your /dev
+directory, use can see the /dev/fd0D720 has major 2 and minor 16. You
+can specify this device for the root FS by writing "root=/dev/fd16" on
+the kernel command line.
+
+[Strange and maybe uninteresting stuff ON]
+
+This unusual translation of device names has some strange
+consequences: If, for example, you have a symbolic link from /dev/fd
+to /dev/fd0D720 as an abbreviation for floppy driver #0 in DD format,
+you cannot use this name for specifying the root device, because the
+kernel cannot see this symlink before mounting the root FS and it
+isn't in the table above. If you use it, the root device will not be
+set at all, without an error message. Another example: You cannot use a
+partition on e.g. the sixth SCSI disk as the root filesystem, if you
+want to specify it by name. This is, because only the devices up to
+/dev/sde are in the table above, but not /dev/sdf. Although, you can
+use the sixth SCSI disk for the root FS, but you have to specify the
+device by number... (see below). Or, even more strange, you can use the
+fact that there is no range checking of the partition number, and your
+knowledge that each disk uses 16 minors, and write "root=/dev/sde17"
+(for /dev/sdf1).
+
+[Strange and maybe uninteresting stuff OFF]
+
+If the device containing your root partition isn't in the table
+above, you can also specify it by major and minor numbers. These are
+written in hex, with no prefix and no separator between. E.g., if you
+have a CD with contents appropriate as a root filesystem in the first
+SCSI CD-ROM drive, you boot from it by "root=0b00". Here, hex "0b" =
+decimal 11 is the major of SCSI CD-ROMs, and the minor 0 stands for
+the first of these. You can find out all valid major numbers by
+looking into include/linux/major.h.
+
+In addition to major and minor numbers, if the device containing your
+root partition uses a partition table format with unique partition
+identifiers, then you may use them.  For instance,
+"root=PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF".  It is also
+possible to reference another partition on the same device using a
+known partition UUID as the starting point.  For example,
+if partition 5 of the device has the UUID of
+00112233-4455-6677-8899-AABBCCDDEEFF then partition 3 may be found as
+follows:
+
+  PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF/PARTNROFF=-2
+
+Authoritative information can be found in
+"Documentation/admin-guide/kernel-parameters.rst".
+
+
+2.2) ro, rw
+-----------
+
+:Syntax: ro
+:or:     rw
+
+These two options tell the kernel whether it should mount the root
+filesystem read-only or read-write. The default is read-only, except
+for ramdisks, which default to read-write.
+
+
+2.3) debug
+----------
+
+:Syntax: debug
+
+This raises the kernel log level to 10 (the default is 7). This is the
+same level as set by the "dmesg" command, just that the maximum level
+selectable by dmesg is 8.
+
+
+2.4) debug=
+-----------
+
+:Syntax: debug=<device>
+
+This option causes certain kernel messages be printed to the selected
+debugging device. This can aid debugging the kernel, since the
+messages can be captured and analyzed on some other machine. Which
+devices are possible depends on the machine type. There are no checks
+for the validity of the device name. If the device isn't implemented,
+nothing happens.
+
+Messages logged this way are in general stack dumps after kernel
+memory faults or bad kernel traps, and kernel panics. To be exact: all
+messages of level 0 (panic messages) and all messages printed while
+the log level is 8 or more (their level doesn't matter). Before stack
+dumps, the kernel sets the log level to 10 automatically. A level of
+at least 8 can also be set by the "debug" command line option (see
+2.3) and at run time with "dmesg -n 8".
+
+Devices possible for Amiga:
+
+ - "ser":
+	  built-in serial port; parameters: 9600bps, 8N1
+ - "mem":
+	  Save the messages to a reserved area in chip mem. After
+          rebooting, they can be read under AmigaOS with the tool
+          'dmesg'.
+
+Devices possible for Atari:
+
+ - "ser1":
+	   ST-MFP serial port ("Modem1"); parameters: 9600bps, 8N1
+ - "ser2":
+	   SCC channel B serial port ("Modem2"); parameters: 9600bps, 8N1
+ - "ser" :
+	   default serial port
+           This is "ser2" for a Falcon, and "ser1" for any other machine
+ - "midi":
+	   The MIDI port; parameters: 31250bps, 8N1
+ - "par" :
+	   parallel port
+
+           The printing routine for this implements a timeout for the
+           case there's no printer connected (else the kernel would
+           lock up). The timeout is not exact, but usually a few
+           seconds.
+
+
+2.6) ramdisk_size=
+------------------
+
+:Syntax: ramdisk_size=<size>
+
+This option instructs the kernel to set up a ramdisk of the given
+size in KBytes. Do not use this option if the ramdisk contents are
+passed by bootstrap! In this case, the size is selected automatically
+and should not be overwritten.
+
+The only application is for root filesystems on floppy disks, that
+should be loaded into memory. To do that, select the corresponding
+size of the disk as ramdisk size, and set the root device to the disk
+drive (with "root=").
+
+
+2.7) swap=
+
+  I can't find any sign of this option in 2.2.6.
+
+2.8) buff=
+-----------
+
+  I can't find any sign of this option in 2.2.6.
+
+
+3) General Device Options (Amiga and Atari)
+===========================================
+
+3.1) ether=
+-----------
+
+:Syntax: ether=[<irq>[,<base_addr>[,<mem_start>[,<mem_end>]]]],<dev-name>
+
+<dev-name> is the name of a net driver, as specified in
+drivers/net/Space.c in the Linux source. Most prominent are eth0, ...
+eth3, sl0, ... sl3, ppp0, ..., ppp3, dummy, and lo.
+
+The non-ethernet drivers (sl, ppp, dummy, lo) obviously ignore the
+settings by this options. Also, the existing ethernet drivers for
+Linux/m68k (ariadne, a2065, hydra) don't use them because Zorro boards
+are really Plug-'n-Play, so the "ether=" option is useless altogether
+for Linux/m68k.
+
+
+3.2) hd=
+--------
+
+:Syntax: hd=<cylinders>,<heads>,<sectors>
+
+This option sets the disk geometry of an IDE disk. The first hd=
+option is for the first IDE disk, the second for the second one.
+(I.e., you can give this option twice.) In most cases, you won't have
+to use this option, since the kernel can obtain the geometry data
+itself. It exists just for the case that this fails for one of your
+disks.
+
+
+3.3) max_scsi_luns=
+-------------------
+
+:Syntax: max_scsi_luns=<n>
+
+Sets the maximum number of LUNs (logical units) of SCSI devices to
+be scanned. Valid values for <n> are between 1 and 8. Default is 8 if
+"Probe all LUNs on each SCSI device" was selected during the kernel
+configuration, else 1.
+
+
+3.4) st=
+--------
+
+:Syntax: st=<buffer_size>,[<write_thres>,[<max_buffers>]]
+
+Sets several parameters of the SCSI tape driver. <buffer_size> is
+the number of 512-byte buffers reserved for tape operations for each
+device. <write_thres> sets the number of blocks which must be filled
+to start an actual write operation to the tape. Maximum value is the
+total number of buffers. <max_buffer> limits the total number of
+buffers allocated for all tape devices.
+
+
+3.5) dmasound=
+--------------
+
+:Syntax: dmasound=[<buffers>,<buffer-size>[,<catch-radius>]]
+
+This option controls some configurations of the Linux/m68k DMA sound
+driver (Amiga and Atari): <buffers> is the number of buffers you want
+to use (minimum 4, default 4), <buffer-size> is the size of each
+buffer in kilobytes (minimum 4, default 32) and <catch-radius> says
+how much percent of error will be tolerated when setting a frequency
+(maximum 10, default 0). For example with 3% you can play 8000Hz
+AU-Files on the Falcon with its hardware frequency of 8195Hz and thus
+don't need to expand the sound.
+
+
+
+4) Options for Atari Only
+=========================
+
+4.1) video=
+-----------
+
+:Syntax: video=<fbname>:<sub-options...>
+
+The <fbname> parameter specifies the name of the frame buffer,
+eg. most atari users will want to specify `atafb` here. The
+<sub-options> is a comma-separated list of the sub-options listed
+below.
+
+NB:
+    Please notice that this option was renamed from `atavideo` to
+    `video` during the development of the 1.3.x kernels, thus you
+    might need to update your boot-scripts if upgrading to 2.x from
+    an 1.2.x kernel.
+
+NBB:
+    The behavior of video= was changed in 2.1.57 so the recommended
+    option is to specify the name of the frame buffer.
+
+4.1.1) Video Mode
+-----------------
+
+This sub-option may be any of the predefined video modes, as listed
+in atari/atafb.c in the Linux/m68k source tree. The kernel will
+activate the given video mode at boot time and make it the default
+mode, if the hardware allows. Currently defined names are:
+
+ - stlow           : 320x200x4
+ - stmid, default5 : 640x200x2
+ - sthigh, default4: 640x400x1
+ - ttlow           : 320x480x8, TT only
+ - ttmid, default1 : 640x480x4, TT only
+ - tthigh, default2: 1280x960x1, TT only
+ - vga2            : 640x480x1, Falcon only
+ - vga4            : 640x480x2, Falcon only
+ - vga16, default3 : 640x480x4, Falcon only
+ - vga256          : 640x480x8, Falcon only
+ - falh2           : 896x608x1, Falcon only
+ - falh16          : 896x608x4, Falcon only
+
+If no video mode is given on the command line, the kernel tries the
+modes names "default<n>" in turn, until one is possible with the
+hardware in use.
+
+A video mode setting doesn't make sense, if the external driver is
+activated by a "external:" sub-option.
+
+4.1.2) inverse
+--------------
+
+Invert the display. This affects only text consoles.
+Usually, the background is chosen to be black. With this
+option, you can make the background white.
+
+4.1.3) font
+-----------
+
+:Syntax: font:<fontname>
+
+Specify the font to use in text modes. Currently you can choose only
+between `VGA8x8`, `VGA8x16` and `PEARL8x8`. `VGA8x8` is default, if the
+vertical size of the display is less than 400 pixel rows. Otherwise, the
+`VGA8x16` font is the default.
+
+4.1.4) `hwscroll_`
+------------------
+
+:Syntax: `hwscroll_<n>`
+
+The number of additional lines of video memory to reserve for
+speeding up the scrolling ("hardware scrolling"). Hardware scrolling
+is possible only if the kernel can set the video base address in steps
+fine enough. This is true for STE, MegaSTE, TT, and Falcon. It is not
+possible with plain STs and graphics cards (The former because the
+base address must be on a 256 byte boundary there, the latter because
+the kernel doesn't know how to set the base address at all.)
+
+By default, <n> is set to the number of visible text lines on the
+display. Thus, the amount of video memory is doubled, compared to no
+hardware scrolling. You can turn off the hardware scrolling altogether
+by setting <n> to 0.
+
+4.1.5) internal:
+----------------
+
+:Syntax: internal:<xres>;<yres>[;<xres_max>;<yres_max>;<offset>]
+
+This option specifies the capabilities of some extended internal video
+hardware, like e.g. OverScan. <xres> and <yres> give the (extended)
+dimensions of the screen.
+
+If your OverScan needs a black border, you have to write the last
+three arguments of the "internal:". <xres_max> is the maximum line
+length the hardware allows, <yres_max> the maximum number of lines.
+<offset> is the offset of the visible part of the screen memory to its
+physical start, in bytes.
+
+Often, extended interval video hardware has to be activated somehow.
+For this, see the "sw_*" options below.
+
+4.1.6) external:
+----------------
+
+:Syntax:
+  external:<xres>;<yres>;<depth>;<org>;<scrmem>[;<scrlen>[;<vgabase>
+  [;<colw>[;<coltype>[;<xres_virtual>]]]]]
+
+.. I had to break this line...
+
+This is probably the most complicated parameter... It specifies that
+you have some external video hardware (a graphics board), and how to
+use it under Linux/m68k. The kernel cannot know more about the hardware
+than you tell it here! The kernel also is unable to set or change any
+video modes, since it doesn't know about any board internal. So, you
+have to switch to that video mode before you start Linux, and cannot
+switch to another mode once Linux has started.
+
+The first 3 parameters of this sub-option should be obvious: <xres>,
+<yres> and <depth> give the dimensions of the screen and the number of
+planes (depth). The depth is the logarithm to base 2 of the number
+of colors possible. (Or, the other way round: The number of colors is
+2^depth).
+
+You have to tell the kernel furthermore how the video memory is
+organized. This is done by a letter as <org> parameter:
+
+ 'n':
+      "normal planes", i.e. one whole plane after another
+ 'i':
+      "interleaved planes", i.e. 16 bit of the first plane, than 16 bit
+      of the next, and so on... This mode is used only with the
+      built-in Atari video modes, I think there is no card that
+      supports this mode.
+ 'p':
+      "packed pixels", i.e. <depth> consecutive bits stand for all
+      planes of one pixel; this is the most common mode for 8 planes
+      (256 colors) on graphic cards
+ 't':
+      "true color" (more or less packed pixels, but without a color
+      lookup table); usually depth is 24
+
+For monochrome modes (i.e., <depth> is 1), the <org> letter has a
+different meaning:
+
+ 'n':
+      normal colors, i.e. 0=white, 1=black
+ 'i':
+      inverted colors, i.e. 0=black, 1=white
+
+The next important information about the video hardware is the base
+address of the video memory. That is given in the <scrmem> parameter,
+as a hexadecimal number with a "0x" prefix. You have to find out this
+address in the documentation of your hardware.
+
+The next parameter, <scrlen>, tells the kernel about the size of the
+video memory. If it's missing, the size is calculated from <xres>,
+<yres>, and <depth>. For now, it is not useful to write a value here.
+It would be used only for hardware scrolling (which isn't possible
+with the external driver, because the kernel cannot set the video base
+address), or for virtual resolutions under X (which the X server
+doesn't support yet). So, it's currently best to leave this field
+empty, either by ending the "external:" after the video address or by
+writing two consecutive semicolons, if you want to give a <vgabase>
+(it is allowed to leave this parameter empty).
+
+The <vgabase> parameter is optional. If it is not given, the kernel
+cannot read or write any color registers of the video hardware, and
+thus you have to set appropriate colors before you start Linux. But if
+your card is somehow VGA compatible, you can tell the kernel the base
+address of the VGA register set, so it can change the color lookup
+table. You have to look up this address in your board's documentation.
+To avoid misunderstandings: <vgabase> is the _base_ address, i.e. a 4k
+aligned address. For read/writing the color registers, the kernel
+uses the addresses vgabase+0x3c7...vgabase+0x3c9. The <vgabase>
+parameter is written in hexadecimal with a "0x" prefix, just as
+<scrmem>.
+
+<colw> is meaningful only if <vgabase> is specified. It tells the
+kernel how wide each of the color register is, i.e. the number of bits
+per single color (red/green/blue). Default is 6, another quite usual
+value is 8.
+
+Also <coltype> is used together with <vgabase>. It tells the kernel
+about the color register model of your gfx board. Currently, the types
+"vga" (which is also the default) and "mv300" (SANG MV300) are
+implemented.
+
+Parameter <xres_virtual> is required for ProMST or ET4000 cards where
+the physical linelength differs from the visible length. With ProMST,
+xres_virtual must be set to 2048. For ET4000, xres_virtual depends on the
+initialisation of the video-card.
+If you're missing a corresponding yres_virtual: the external part is legacy,
+therefore we don't support hardware-dependent functions like hardware-scroll,
+panning or blanking.
+
+4.1.7) eclock:
+--------------
+
+The external pixel clock attached to the Falcon VIDEL shifter. This
+currently works only with the ScreenWonder!
+
+4.1.8) monitorcap:
+-------------------
+
+:Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>
+
+This describes the capabilities of a multisync monitor. Don't use it
+with a fixed-frequency monitor! For now, only the Falcon frame buffer
+uses the settings of "monitorcap:".
+
+<vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
+your monitor can work with, in Hz. <hmin> and <hmax> are the same for
+the horizontal frequency, in kHz.
+
+  The defaults are 58;62;31;32 (VGA compatible).
+
+  The defaults for TV/SC1224/SC1435 cover both PAL and NTSC standards.
+
+4.1.9) keep
+------------
+
+If this option is given, the framebuffer device doesn't do any video
+mode calculations and settings on its own. The only Atari fb device
+that does this currently is the Falcon.
+
+What you reach with this: Settings for unknown video extensions
+aren't overridden by the driver, so you can still use the mode found
+when booting, when the driver doesn't know to set this mode itself.
+But this also means, that you can't switch video modes anymore...
+
+An example where you may want to use "keep" is the ScreenBlaster for
+the Falcon.
+
+
+4.2) atamouse=
+--------------
+
+:Syntax: atamouse=<x-threshold>,[<y-threshold>]
+
+With this option, you can set the mouse movement reporting threshold.
+This is the number of pixels of mouse movement that have to accumulate
+before the IKBD sends a new mouse packet to the kernel. Higher values
+reduce the mouse interrupt load and thus reduce the chance of keyboard
+overruns. Lower values give a slightly faster mouse responses and
+slightly better mouse tracking.
+
+You can set the threshold in x and y separately, but usually this is
+of little practical use. If there's just one number in the option, it
+is used for both dimensions. The default value is 2 for both
+thresholds.
+
+
+4.3) ataflop=
+-------------
+
+:Syntax: ataflop=<drive type>[,<trackbuffering>[,<steprateA>[,<steprateB>]]]
+
+   The drive type may be 0, 1, or 2, for DD, HD, and ED, resp. This
+   setting affects how many buffers are reserved and which formats are
+   probed (see also below). The default is 1 (HD). Only one drive type
+   can be selected. If you have two disk drives, select the "better"
+   type.
+
+   The second parameter <trackbuffer> tells the kernel whether to use
+   track buffering (1) or not (0). The default is machine-dependent:
+   no for the Medusa and yes for all others.
+
+   With the two following parameters, you can change the default
+   steprate used for drive A and B, resp.
+
+
+4.4) atascsi=
+-------------
+
+:Syntax: atascsi=<can_queue>[,<cmd_per_lun>[,<scat-gat>[,<host-id>[,<tagged>]]]]
+
+This option sets some parameters for the Atari native SCSI driver.
+Generally, any number of arguments can be omitted from the end. And
+for each of the numbers, a negative value means "use default". The
+defaults depend on whether TT-style or Falcon-style SCSI is used.
+Below, defaults are noted as n/m, where the first value refers to
+TT-SCSI and the latter to Falcon-SCSI. If an illegal value is given
+for one parameter, an error message is printed and that one setting is
+ignored (others aren't affected).
+
+  <can_queue>:
+    This is the maximum number of SCSI commands queued internally to the
+    Atari SCSI driver. A value of 1 effectively turns off the driver
+    internal multitasking (if it causes problems). Legal values are >=
+    1. <can_queue> can be as high as you like, but values greater than
+    <cmd_per_lun> times the number of SCSI targets (LUNs) you have
+    don't make sense. Default: 16/8.
+
+  <cmd_per_lun>:
+    Maximum number of SCSI commands issued to the driver for one
+    logical unit (LUN, usually one SCSI target). Legal values start
+    from 1. If tagged queuing (see below) is not used, values greater
+    than 2 don't make sense, but waste memory. Otherwise, the maximum
+    is the number of command tags available to the driver (currently
+    32). Default: 8/1. (Note: Values > 1 seem to cause problems on a
+    Falcon, cause not yet known.)
+
+    The <cmd_per_lun> value at a great part determines the amount of
+    memory SCSI reserves for itself. The formula is rather
+    complicated, but I can give you some hints:
+
+      no scatter-gather:
+	cmd_per_lun * 232 bytes
+      full scatter-gather:
+	cmd_per_lun * approx. 17 Kbytes
+
+  <scat-gat>:
+    Size of the scatter-gather table, i.e. the number of requests
+    consecutive on the disk that can be merged into one SCSI command.
+    Legal values are between 0 and 255. Default: 255/0. Note: This
+    value is forced to 0 on a Falcon, since scatter-gather isn't
+    possible with the ST-DMA. Not using scatter-gather hurts
+    performance significantly.
+
+  <host-id>:
+    The SCSI ID to be used by the initiator (your Atari). This is
+    usually 7, the highest possible ID. Every ID on the SCSI bus must
+    be unique. Default: determined at run time: If the NV-RAM checksum
+    is valid, and bit 7 in byte 30 of the NV-RAM is set, the lower 3
+    bits of this byte are used as the host ID. (This method is defined
+    by Atari and also used by some TOS HD drivers.) If the above
+    isn't given, the default ID is 7. (both, TT and Falcon).
+
+  <tagged>:
+    0 means turn off tagged queuing support, all other values > 0 mean
+    use tagged queuing for targets that support it. Default: currently
+    off, but this may change when tagged queuing handling has been
+    proved to be reliable.
+
+    Tagged queuing means that more than one command can be issued to
+    one LUN, and the SCSI device itself orders the requests so they
+    can be performed in optimal order. Not all SCSI devices support
+    tagged queuing (:-().
+
+4.5 switches=
+-------------
+
+:Syntax: switches=<list of switches>
+
+With this option you can switch some hardware lines that are often
+used to enable/disable certain hardware extensions. Examples are
+OverScan, overclocking, ...
+
+The <list of switches> is a comma-separated list of the following
+items:
+
+  ikbd:
+	set RTS of the keyboard ACIA high
+  midi:
+	set RTS of the MIDI ACIA high
+  snd6:
+	set bit 6 of the PSG port A
+  snd7:
+	set bit 6 of the PSG port A
+
+It doesn't make sense to mention a switch more than once (no
+difference to only once), but you can give as many switches as you
+want to enable different features. The switch lines are set as early
+as possible during kernel initialization (even before determining the
+present hardware.)
+
+All of the items can also be prefixed with `ov_`, i.e. `ov_ikbd`,
+`ov_midi`, ... These options are meant for switching on an OverScan
+video extension. The difference to the bare option is that the
+switch-on is done after video initialization, and somehow synchronized
+to the HBLANK. A speciality is that ov_ikbd and ov_midi are switched
+off before rebooting, so that OverScan is disabled and TOS boots
+correctly.
+
+If you give an option both, with and without the `ov_` prefix, the
+earlier initialization (`ov_`-less) takes precedence. But the
+switching-off on reset still happens in this case.
+
+5) Options for Amiga Only:
+==========================
+
+5.1) video=
+-----------
+
+:Syntax: video=<fbname>:<sub-options...>
+
+The <fbname> parameter specifies the name of the frame buffer, valid
+options are `amifb`, `cyber`, 'virge', `retz3` and `clgen`, provided
+that the respective frame buffer devices have been compiled into the
+kernel (or compiled as loadable modules). The behavior of the <fbname>
+option was changed in 2.1.57 so it is now recommended to specify this
+option.
+
+The <sub-options> is a comma-separated list of the sub-options listed
+below. This option is organized similar to the Atari version of the
+"video"-option (4.1), but knows fewer sub-options.
+
+5.1.1) video mode
+-----------------
+
+Again, similar to the video mode for the Atari (see 4.1.1). Predefined
+modes depend on the used frame buffer device.
+
+OCS, ECS and AGA machines all use the color frame buffer. The following
+predefined video modes are available:
+
+NTSC modes:
+ - ntsc            : 640x200, 15 kHz, 60 Hz
+ - ntsc-lace       : 640x400, 15 kHz, 60 Hz interlaced
+
+PAL modes:
+ - pal             : 640x256, 15 kHz, 50 Hz
+ - pal-lace        : 640x512, 15 kHz, 50 Hz interlaced
+
+ECS modes:
+ - multiscan       : 640x480, 29 kHz, 57 Hz
+ - multiscan-lace  : 640x960, 29 kHz, 57 Hz interlaced
+ - euro36          : 640x200, 15 kHz, 72 Hz
+ - euro36-lace     : 640x400, 15 kHz, 72 Hz interlaced
+ - euro72          : 640x400, 29 kHz, 68 Hz
+ - euro72-lace     : 640x800, 29 kHz, 68 Hz interlaced
+ - super72         : 800x300, 23 kHz, 70 Hz
+ - super72-lace    : 800x600, 23 kHz, 70 Hz interlaced
+ - dblntsc-ff      : 640x400, 27 kHz, 57 Hz
+ - dblntsc-lace    : 640x800, 27 kHz, 57 Hz interlaced
+ - dblpal-ff       : 640x512, 27 kHz, 47 Hz
+ - dblpal-lace     : 640x1024, 27 kHz, 47 Hz interlaced
+ - dblntsc         : 640x200, 27 kHz, 57 Hz doublescan
+ - dblpal          : 640x256, 27 kHz, 47 Hz doublescan
+
+VGA modes:
+ - vga             : 640x480, 31 kHz, 60 Hz
+ - vga70           : 640x400, 31 kHz, 70 Hz
+
+Please notice that the ECS and VGA modes require either an ECS or AGA
+chipset, and that these modes are limited to 2-bit color for the ECS
+chipset and 8-bit color for the AGA chipset.
+
+5.1.2) depth
+------------
+
+:Syntax: depth:<nr. of bit-planes>
+
+Specify the number of bit-planes for the selected video-mode.
+
+5.1.3) inverse
+--------------
+
+Use inverted display (black on white). Functionally the same as the
+"inverse" sub-option for the Atari.
+
+5.1.4) font
+-----------
+
+:Syntax: font:<fontname>
+
+Specify the font to use in text modes. Functionally the same as the
+"font" sub-option for the Atari, except that `PEARL8x8` is used instead
+of `VGA8x8` if the vertical size of the display is less than 400 pixel
+rows.
+
+5.1.5) monitorcap:
+-------------------
+
+:Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>
+
+This describes the capabilities of a multisync monitor. For now, only
+the color frame buffer uses the settings of "monitorcap:".
+
+<vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
+your monitor can work with, in Hz. <hmin> and <hmax> are the same for
+the horizontal frequency, in kHz.
+
+The defaults are 50;90;15;38 (Generic Amiga multisync monitor).
+
+
+5.2) fd_def_df0=
+----------------
+
+:Syntax: fd_def_df0=<value>
+
+Sets the df0 value for "silent" floppy drives. The value should be in
+hexadecimal with "0x" prefix.
+
+
+5.3) wd33c93=
+-------------
+
+:Syntax: wd33c93=<sub-options...>
+
+These options affect the A590/A2091, A3000 and GVP Series II SCSI
+controllers.
+
+The <sub-options> is a comma-separated list of the sub-options listed
+below.
+
+5.3.1) nosync
+-------------
+
+:Syntax: nosync:bitmask
+
+bitmask is a byte where the 1st 7 bits correspond with the 7
+possible SCSI devices. Set a bit to prevent sync negotiation on that
+device. To maintain backwards compatibility, a command-line such as
+"wd33c93=255" will be automatically translated to
+"wd33c93=nosync:0xff". The default is to disable sync negotiation for
+all devices, eg. nosync:0xff.
+
+5.3.2) period
+-------------
+
+:Syntax: period:ns
+
+`ns` is the minimum # of nanoseconds in a SCSI data transfer
+period. Default is 500; acceptable values are 250 - 1000.
+
+5.3.3) disconnect
+-----------------
+
+:Syntax: disconnect:x
+
+Specify x = 0 to never allow disconnects, 2 to always allow them.
+x = 1 does 'adaptive' disconnects, which is the default and generally
+the best choice.
+
+5.3.4) debug
+------------
+
+:Syntax: debug:x
+
+If `DEBUGGING_ON` is defined, x is a bit mask that causes various
+types of debug output to printed - see the DB_xxx defines in
+wd33c93.h.
+
+5.3.5) clock
+------------
+
+:Syntax: clock:x
+
+x = clock input in MHz for WD33c93 chip. Normal values would be from
+8 through 20. The default value depends on your hostadapter(s),
+default for the A3000 internal controller is 14, for the A2091 it's 8
+and for the GVP hostadapters it's either 8 or 14, depending on the
+hostadapter and the SCSI-clock jumper present on some GVP
+hostadapters.
+
+5.3.6) next
+-----------
+
+No argument. Used to separate blocks of keywords when there's more
+than one wd33c93-based host adapter in the system.
+
+5.3.7) nodma
+------------
+
+:Syntax: nodma:x
+
+If x is 1 (or if the option is just written as "nodma"), the WD33c93
+controller will not use DMA (= direct memory access) to access the
+Amiga's memory.  This is useful for some systems (like A3000's and
+A4000's with the A3640 accelerator, revision 3.0) that have problems
+using DMA to chip memory.  The default is 0, i.e. to use DMA if
+possible.
+
+
+5.4) gvp11=
+-----------
+
+:Syntax: gvp11=<addr-mask>
+
+The earlier versions of the GVP driver did not handle DMA
+address-mask settings correctly which made it necessary for some
+people to use this option, in order to get their GVP controller
+running under Linux. These problems have hopefully been solved and the
+use of this option is now highly unrecommended!
+
+Incorrect use can lead to unpredictable behavior, so please only use
+this option if you *know* what you are doing and have a reason to do
+so. In any case if you experience problems and need to use this
+option, please inform us about it by mailing to the Linux/68k kernel
+mailing list.
+
+The address mask set by this option specifies which addresses are
+valid for DMA with the GVP Series II SCSI controller. An address is
+valid, if no bits are set except the bits that are set in the mask,
+too.
+
+Some versions of the GVP can only DMA into a 24 bit address range,
+some can address a 25 bit address range while others can use the whole
+32 bit address range for DMA. The correct setting depends on your
+controller and should be autodetected by the driver. An example is the
+24 bit region which is specified by a mask of 0x00fffffe.