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diff --git a/Documentation/powerpc/hvcs.rst b/Documentation/powerpc/hvcs.rst deleted file mode 100644 index 6808acde67..0000000000 --- a/Documentation/powerpc/hvcs.rst +++ /dev/null @@ -1,581 +0,0 @@ -=============================================================== -HVCS IBM "Hypervisor Virtual Console Server" Installation Guide -=============================================================== - -for Linux Kernel 2.6.4+ - -Copyright (C) 2004 IBM Corporation - -.. =========================================================================== -.. NOTE:Eight space tabs are the optimum editor setting for reading this file. -.. =========================================================================== - - -Author(s): Ryan S. Arnold <rsa@us.ibm.com> - -Date Created: March, 02, 2004 -Last Changed: August, 24, 2004 - -.. Table of contents: - - 1. Driver Introduction: - 2. System Requirements - 3. Build Options: - 3.1 Built-in: - 3.2 Module: - 4. Installation: - 5. Connection: - 6. Disconnection: - 7. Configuration: - 8. Questions & Answers: - 9. Reporting Bugs: - -1. Driver Introduction: -======================= - -This is the device driver for the IBM Hypervisor Virtual Console Server, -"hvcs". The IBM hvcs provides a tty driver interface to allow Linux user -space applications access to the system consoles of logically partitioned -operating systems (Linux and AIX) running on the same partitioned Power5 -ppc64 system. Physical hardware consoles per partition are not practical -on this hardware so system consoles are accessed by this driver using -firmware interfaces to virtual terminal devices. - -2. System Requirements: -======================= - -This device driver was written using 2.6.4 Linux kernel APIs and will only -build and run on kernels of this version or later. - -This driver was written to operate solely on IBM Power5 ppc64 hardware -though some care was taken to abstract the architecture dependent firmware -calls from the driver code. - -Sysfs must be mounted on the system so that the user can determine which -major and minor numbers are associated with each vty-server. Directions -for sysfs mounting are outside the scope of this document. - -3. Build Options: -================= - -The hvcs driver registers itself as a tty driver. The tty layer -dynamically allocates a block of major and minor numbers in a quantity -requested by the registering driver. The hvcs driver asks the tty layer -for 64 of these major/minor numbers by default to use for hvcs device node -entries. - -If the default number of device entries is adequate then this driver can be -built into the kernel. If not, the default can be over-ridden by inserting -the driver as a module with insmod parameters. - -3.1 Built-in: -------------- - -The following menuconfig example demonstrates selecting to build this -driver into the kernel:: - - Device Drivers ---> - Character devices ---> - <*> IBM Hypervisor Virtual Console Server Support - -Begin the kernel make process. - -3.2 Module: ------------ - -The following menuconfig example demonstrates selecting to build this -driver as a kernel module:: - - Device Drivers ---> - Character devices ---> - <M> IBM Hypervisor Virtual Console Server Support - -The make process will build the following kernel modules: - - - hvcs.ko - - hvcserver.ko - -To insert the module with the default allocation execute the following -commands in the order they appear:: - - insmod hvcserver.ko - insmod hvcs.ko - -The hvcserver module contains architecture specific firmware calls and must -be inserted first, otherwise the hvcs module will not find some of the -symbols it expects. - -To override the default use an insmod parameter as follows (requesting 4 -tty devices as an example):: - - insmod hvcs.ko hvcs_parm_num_devs=4 - -There is a maximum number of dev entries that can be specified on insmod. -We think that 1024 is currently a decent maximum number of server adapters -to allow. This can always be changed by modifying the constant in the -source file before building. - -NOTE: The length of time it takes to insmod the driver seems to be related -to the number of tty interfaces the registering driver requests. - -In order to remove the driver module execute the following command:: - - rmmod hvcs.ko - -The recommended method for installing hvcs as a module is to use depmod to -build a current modules.dep file in /lib/modules/`uname -r` and then -execute:: - - modprobe hvcs hvcs_parm_num_devs=4 - -The modules.dep file indicates that hvcserver.ko needs to be inserted -before hvcs.ko and modprobe uses this file to smartly insert the modules in -the proper order. - -The following modprobe command is used to remove hvcs and hvcserver in the -proper order:: - - modprobe -r hvcs - -4. Installation: -================ - -The tty layer creates sysfs entries which contain the major and minor -numbers allocated for the hvcs driver. The following snippet of "tree" -output of the sysfs directory shows where these numbers are presented:: - - sys/ - |-- *other sysfs base dirs* - | - |-- class - | |-- *other classes of devices* - | | - | `-- tty - | |-- *other tty devices* - | | - | |-- hvcs0 - | | `-- dev - | |-- hvcs1 - | | `-- dev - | |-- hvcs2 - | | `-- dev - | |-- hvcs3 - | | `-- dev - | | - | |-- *other tty devices* - | - |-- *other sysfs base dirs* - -For the above examples the following output is a result of cat'ing the -"dev" entry in the hvcs directory:: - - Pow5:/sys/class/tty/hvcs0/ # cat dev - 254:0 - - Pow5:/sys/class/tty/hvcs1/ # cat dev - 254:1 - - Pow5:/sys/class/tty/hvcs2/ # cat dev - 254:2 - - Pow5:/sys/class/tty/hvcs3/ # cat dev - 254:3 - -The output from reading the "dev" attribute is the char device major and -minor numbers that the tty layer has allocated for this driver's use. Most -systems running hvcs will already have the device entries created or udev -will do it automatically. - -Given the example output above, to manually create a /dev/hvcs* node entry -mknod can be used as follows:: - - mknod /dev/hvcs0 c 254 0 - mknod /dev/hvcs1 c 254 1 - mknod /dev/hvcs2 c 254 2 - mknod /dev/hvcs3 c 254 3 - -Using mknod to manually create the device entries makes these device nodes -persistent. Once created they will exist prior to the driver insmod. - -Attempting to connect an application to /dev/hvcs* prior to insertion of -the hvcs module will result in an error message similar to the following:: - - "/dev/hvcs*: No such device". - -NOTE: Just because there is a device node present doesn't mean that there -is a vty-server device configured for that node. - -5. Connection -============= - -Since this driver controls devices that provide a tty interface a user can -interact with the device node entries using any standard tty-interactive -method (e.g. "cat", "dd", "echo"). The intent of this driver however, is -to provide real time console interaction with a Linux partition's console, -which requires the use of applications that provide bi-directional, -interactive I/O with a tty device. - -Applications (e.g. "minicom" and "screen") that act as terminal emulators -or perform terminal type control sequence conversion on the data being -passed through them are NOT acceptable for providing interactive console -I/O. These programs often emulate antiquated terminal types (vt100 and -ANSI) and expect inbound data to take the form of one of these supported -terminal types but they either do not convert, or do not _adequately_ -convert, outbound data into the terminal type of the terminal which invoked -them (though screen makes an attempt and can apparently be configured with -much termcap wrestling.) - -For this reason kermit and cu are two of the recommended applications for -interacting with a Linux console via an hvcs device. These programs simply -act as a conduit for data transfer to and from the tty device. They do not -require inbound data to take the form of a particular terminal type, nor do -they cook outbound data to a particular terminal type. - -In order to ensure proper functioning of console applications one must make -sure that once connected to a /dev/hvcs console that the console's $TERM -env variable is set to the exact terminal type of the terminal emulator -used to launch the interactive I/O application. If one is using xterm and -kermit to connect to /dev/hvcs0 when the console prompt becomes available -one should "export TERM=xterm" on the console. This tells ncurses -applications that are invoked from the console that they should output -control sequences that xterm can understand. - -As a precautionary measure an hvcs user should always "exit" from their -session before disconnecting an application such as kermit from the device -node. If this is not done, the next user to connect to the console will -continue using the previous user's logged in session which includes -using the $TERM variable that the previous user supplied. - -Hotplug add and remove of vty-server adapters affects which /dev/hvcs* node -is used to connect to each vty-server adapter. In order to determine which -vty-server adapter is associated with which /dev/hvcs* node a special sysfs -attribute has been added to each vty-server sysfs entry. This entry is -called "index" and showing it reveals an integer that refers to the -/dev/hvcs* entry to use to connect to that device. For instance cating the -index attribute of vty-server adapter 30000004 shows the following:: - - Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat index - 2 - -This index of '2' means that in order to connect to vty-server adapter -30000004 the user should interact with /dev/hvcs2. - -It should be noted that due to the system hotplug I/O capabilities of a -system the /dev/hvcs* entry that interacts with a particular vty-server -adapter is not guaranteed to remain the same across system reboots. Look -in the Q & A section for more on this issue. - -6. Disconnection -================ - -As a security feature to prevent the delivery of stale data to an -unintended target the Power5 system firmware disables the fetching of data -and discards that data when a connection between a vty-server and a vty has -been severed. As an example, when a vty-server is immediately disconnected -from a vty following output of data to the vty the vty adapter may not have -enough time between when it received the data interrupt and when the -connection was severed to fetch the data from firmware before the fetch is -disabled by firmware. - -When hvcs is being used to serve consoles this behavior is not a huge issue -because the adapter stays connected for large amounts of time following -almost all data writes. When hvcs is being used as a tty conduit to tunnel -data between two partitions [see Q & A below] this is a huge problem -because the standard Linux behavior when cat'ing or dd'ing data to a device -is to open the tty, send the data, and then close the tty. If this driver -manually terminated vty-server connections on tty close this would close -the vty-server and vty connection before the target vty has had a chance to -fetch the data. - -Additionally, disconnecting a vty-server and vty only on module removal or -adapter removal is impractical because other vty-servers in other -partitions may require the usage of the target vty at any time. - -Due to this behavioral restriction disconnection of vty-servers from the -connected vty is a manual procedure using a write to a sysfs attribute -outlined below, on the other hand the initial vty-server connection to a -vty is established automatically by this driver. Manual vty-server -connection is never required. - -In order to terminate the connection between a vty-server and vty the -"vterm_state" sysfs attribute within each vty-server's sysfs entry is used. -Reading this attribute reveals the current connection state of the -vty-server adapter. A zero means that the vty-server is not connected to a -vty. A one indicates that a connection is active. - -Writing a '0' (zero) to the vterm_state attribute will disconnect the VTERM -connection between the vty-server and target vty ONLY if the vterm_state -previously read '1'. The write directive is ignored if the vterm_state -read '0' or if any value other than '0' was written to the vterm_state -attribute. The following example will show the method used for verifying -the vty-server connection status and disconnecting a vty-server connection:: - - Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat vterm_state - 1 - - Pow5:/sys/bus/vio/drivers/hvcs/30000004 # echo 0 > vterm_state - - Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat vterm_state - 0 - -All vty-server connections are automatically terminated when the device is -hotplug removed and when the module is removed. - -7. Configuration -================ - -Each vty-server has a sysfs entry in the /sys/devices/vio directory, which -is symlinked in several other sysfs tree directories, notably under the -hvcs driver entry, which looks like the following example:: - - Pow5:/sys/bus/vio/drivers/hvcs # ls - . .. 30000003 30000004 rescan - -By design, firmware notifies the hvcs driver of vty-server lifetimes and -partner vty removals but not the addition of partner vtys. Since an HMC -Super Admin can add partner info dynamically we have provided the hvcs -driver sysfs directory with the "rescan" update attribute which will query -firmware and update the partner info for all the vty-servers that this -driver manages. Writing a '1' to the attribute triggers the update. An -explicit example follows: - - Pow5:/sys/bus/vio/drivers/hvcs # echo 1 > rescan - -Reading the attribute will indicate a state of '1' or '0'. A one indicates -that an update is in process. A zero indicates that an update has -completed or was never executed. - -Vty-server entries in this directory are a 32 bit partition unique unit -address that is created by firmware. An example vty-server sysfs entry -looks like the following:: - - Pow5:/sys/bus/vio/drivers/hvcs/30000004 # ls - . current_vty devspec name partner_vtys - .. index partner_clcs vterm_state - -Each entry is provided, by default with a "name" attribute. Reading the -"name" attribute will reveal the device type as shown in the following -example:: - - Pow5:/sys/bus/vio/drivers/hvcs/30000003 # cat name - vty-server - -Each entry is also provided, by default, with a "devspec" attribute which -reveals the full device specification when read, as shown in the following -example:: - - Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat devspec - /vdevice/vty-server@30000004 - -Each vty-server sysfs dir is provided with two read-only attributes that -provide lists of easily parsed partner vty data: "partner_vtys" and -"partner_clcs":: - - Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat partner_vtys - 30000000 - 30000001 - 30000002 - 30000000 - 30000000 - - Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat partner_clcs - U5112.428.103048A-V3-C0 - U5112.428.103048A-V3-C2 - U5112.428.103048A-V3-C3 - U5112.428.103048A-V4-C0 - U5112.428.103048A-V5-C0 - -Reading partner_vtys returns a list of partner vtys. Vty unit address -numbering is only per-partition-unique so entries will frequently repeat. - -Reading partner_clcs returns a list of "converged location codes" which are -composed of a system serial number followed by "-V*", where the '*' is the -target partition number, and "-C*", where the '*' is the slot of the -adapter. The first vty partner corresponds to the first clc item, the -second vty partner to the second clc item, etc. - -A vty-server can only be connected to a single vty at a time. The entry, -"current_vty" prints the clc of the currently selected partner vty when -read. - -The current_vty can be changed by writing a valid partner clc to the entry -as in the following example:: - - Pow5:/sys/bus/vio/drivers/hvcs/30000004 # echo U5112.428.10304 - 8A-V4-C0 > current_vty - -Changing the current_vty when a vty-server is already connected to a vty -does not affect the current connection. The change takes effect when the -currently open connection is freed. - -Information on the "vterm_state" attribute was covered earlier on the -chapter entitled "disconnection". - -8. Questions & Answers: -======================= - -Q: What are the security concerns involving hvcs? - -A: There are three main security concerns: - - 1. The creator of the /dev/hvcs* nodes has the ability to restrict - the access of the device entries to certain users or groups. It - may be best to create a special hvcs group privilege for providing - access to system consoles. - - 2. To provide network security when grabbing the console it is - suggested that the user connect to the console hosting partition - using a secure method, such as SSH or sit at a hardware console. - - 3. Make sure to exit the user session when done with a console or - the next vty-server connection (which may be from another - partition) will experience the previously logged in session. - ---------------------------------------------------------------------------- - -Q: How do I multiplex a console that I grab through hvcs so that other -people can see it: - -A: You can use "screen" to directly connect to the /dev/hvcs* device and -setup a session on your machine with the console group privileges. As -pointed out earlier by default screen doesn't provide the termcap settings -for most terminal emulators to provide adequate character conversion from -term type "screen" to others. This means that curses based programs may -not display properly in screen sessions. - ---------------------------------------------------------------------------- - -Q: Why are the colors all messed up? -Q: Why are the control characters acting strange or not working? -Q: Why is the console output all strange and unintelligible? - -A: Please see the preceding section on "Connection" for a discussion of how -applications can affect the display of character control sequences. -Additionally, just because you logged into the console using and xterm -doesn't mean someone else didn't log into the console with the HMC console -(vt320) before you and leave the session logged in. The best thing to do -is to export TERM to the terminal type of your terminal emulator when you -get the console. Additionally make sure to "exit" the console before you -disconnect from the console. This will ensure that the next user gets -their own TERM type set when they login. - ---------------------------------------------------------------------------- - -Q: When I try to CONNECT kermit to an hvcs device I get: -"Sorry, can't open connection: /dev/hvcs*"What is happening? - -A: Some other Power5 console mechanism has a connection to the vty and -isn't giving it up. You can try to force disconnect the consoles from the -HMC by right clicking on the partition and then selecting "close terminal". -Otherwise you have to hunt down the people who have console authority. It -is possible that you already have the console open using another kermit -session and just forgot about it. Please review the console options for -Power5 systems to determine the many ways a system console can be held. - -OR - -A: Another user may not have a connectivity method currently attached to a -/dev/hvcs device but the vterm_state may reveal that they still have the -vty-server connection established. They need to free this using the method -outlined in the section on "Disconnection" in order for others to connect -to the target vty. - -OR - -A: The user profile you are using to execute kermit probably doesn't have -permissions to use the /dev/hvcs* device. - -OR - -A: You probably haven't inserted the hvcs.ko module yet but the /dev/hvcs* -entry still exists (on systems without udev). - -OR - -A: There is not a corresponding vty-server device that maps to an existing -/dev/hvcs* entry. - ---------------------------------------------------------------------------- - -Q: When I try to CONNECT kermit to an hvcs device I get: -"Sorry, write access to UUCP lockfile directory denied." - -A: The /dev/hvcs* entry you have specified doesn't exist where you said it -does? Maybe you haven't inserted the module (on systems with udev). - ---------------------------------------------------------------------------- - -Q: If I already have one Linux partition installed can I use hvcs on said -partition to provide the console for the install of a second Linux -partition? - -A: Yes granted that your are connected to the /dev/hvcs* device using -kermit or cu or some other program that doesn't provide terminal emulation. - ---------------------------------------------------------------------------- - -Q: Can I connect to more than one partition's console at a time using this -driver? - -A: Yes. Of course this means that there must be more than one vty-server -configured for this partition and each must point to a disconnected vty. - ---------------------------------------------------------------------------- - -Q: Does the hvcs driver support dynamic (hotplug) addition of devices? - -A: Yes, if you have dlpar and hotplug enabled for your system and it has -been built into the kernel the hvcs drivers is configured to dynamically -handle additions of new devices and removals of unused devices. - ---------------------------------------------------------------------------- - -Q: For some reason /dev/hvcs* doesn't map to the same vty-server adapter -after a reboot. What happened? - -A: Assignment of vty-server adapters to /dev/hvcs* entries is always done -in the order that the adapters are exposed. Due to hotplug capabilities of -this driver assignment of hotplug added vty-servers may be in a different -order than how they would be exposed on module load. Rebooting or -reloading the module after dynamic addition may result in the /dev/hvcs* -and vty-server coupling changing if a vty-server adapter was added in a -slot between two other vty-server adapters. Refer to the section above -on how to determine which vty-server goes with which /dev/hvcs* node. -Hint; look at the sysfs "index" attribute for the vty-server. - ---------------------------------------------------------------------------- - -Q: Can I use /dev/hvcs* as a conduit to another partition and use a tty -device on that partition as the other end of the pipe? - -A: Yes, on Power5 platforms the hvc_console driver provides a tty interface -for extra /dev/hvc* devices (where /dev/hvc0 is most likely the console). -In order to get a tty conduit working between the two partitions the HMC -Super Admin must create an additional "serial server" for the target -partition with the HMC gui which will show up as /dev/hvc* when the target -partition is rebooted. - -The HMC Super Admin then creates an additional "serial client" for the -current partition and points this at the target partition's newly created -"serial server" adapter (remember the slot). This shows up as an -additional /dev/hvcs* device. - -Now a program on the target system can be configured to read or write to -/dev/hvc* and another program on the current partition can be configured to -read or write to /dev/hvcs*. Now you have a tty conduit between two -partitions. - ---------------------------------------------------------------------------- - -9. Reporting Bugs: -================== - -The proper channel for reporting bugs is either through the Linux OS -distribution company that provided your OS or by posting issues to the -PowerPC development mailing list at: - -linuxppc-dev@lists.ozlabs.org - -This request is to provide a documented and searchable public exchange -of the problems and solutions surrounding this driver for the benefit of -all users. |