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diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt deleted file mode 100644 index ab7d16efa96b..000000000000 --- a/Documentation/sysctl/kernel.txt +++ /dev/null @@ -1,680 +0,0 @@ -Documentation for /proc/sys/kernel/* kernel version 2.2.10 - (c) 1998, 1999, Rik van Riel <riel@nl.linux.org> - (c) 2009, Shen Feng<shen@cn.fujitsu.com> - -For general info and legal blurb, please look in README. - -============================================================== - -This file contains documentation for the sysctl files in -/proc/sys/kernel/ and is valid for Linux kernel version 2.2. - -The files in this directory can be used to tune and monitor -miscellaneous and general things in the operation of the Linux -kernel. Since some of the files _can_ be used to screw up your -system, it is advisable to read both documentation and source -before actually making adjustments. - -Currently, these files might (depending on your configuration) -show up in /proc/sys/kernel: - -- acct -- acpi_video_flags -- auto_msgmni -- bootloader_type [ X86 only ] -- bootloader_version [ X86 only ] -- callhome [ S390 only ] -- cap_last_cap -- core_pattern -- core_pipe_limit -- core_uses_pid -- ctrl-alt-del -- dmesg_restrict -- domainname -- hostname -- hotplug -- kptr_restrict -- kstack_depth_to_print [ X86 only ] -- l2cr [ PPC only ] -- modprobe ==> Documentation/debugging-modules.txt -- modules_disabled -- msg_next_id [ sysv ipc ] -- msgmax -- msgmnb -- msgmni -- nmi_watchdog -- osrelease -- ostype -- overflowgid -- overflowuid -- panic -- panic_on_oops -- panic_on_unrecovered_nmi -- panic_on_stackoverflow -- pid_max -- powersave-nap [ PPC only ] -- printk -- printk_delay -- printk_ratelimit -- printk_ratelimit_burst -- randomize_va_space -- real-root-dev ==> Documentation/initrd.txt -- reboot-cmd [ SPARC only ] -- rtsig-max -- rtsig-nr -- sem -- sem_next_id [ sysv ipc ] -- sg-big-buff [ generic SCSI device (sg) ] -- shm_next_id [ sysv ipc ] -- shm_rmid_forced -- shmall -- shmmax [ sysv ipc ] -- shmmni -- stop-a [ SPARC only ] -- sysrq ==> Documentation/sysrq.txt -- tainted -- threads-max -- unknown_nmi_panic -- watchdog_thresh -- version - -============================================================== - -acct: - -highwater lowwater frequency - -If BSD-style process accounting is enabled these values control -its behaviour. If free space on filesystem where the log lives -goes below <lowwater>% accounting suspends. If free space gets -above <highwater>% accounting resumes. <Frequency> determines -how often do we check the amount of free space (value is in -seconds). Default: -4 2 30 -That is, suspend accounting if there left <= 2% free; resume it -if we got >=4%; consider information about amount of free space -valid for 30 seconds. - -============================================================== - -acpi_video_flags: - -flags - -See Doc*/kernel/power/video.txt, it allows mode of video boot to be -set during run time. - -============================================================== - -auto_msgmni: - -Enables/Disables automatic recomputing of msgmni upon memory add/remove -or upon ipc namespace creation/removal (see the msgmni description -above). Echoing "1" into this file enables msgmni automatic recomputing. -Echoing "0" turns it off. auto_msgmni default value is 1. - - -============================================================== - -bootloader_type: - -x86 bootloader identification - -This gives the bootloader type number as indicated by the bootloader, -shifted left by 4, and OR'd with the low four bits of the bootloader -version. The reason for this encoding is that this used to match the -type_of_loader field in the kernel header; the encoding is kept for -backwards compatibility. That is, if the full bootloader type number -is 0x15 and the full version number is 0x234, this file will contain -the value 340 = 0x154. - -See the type_of_loader and ext_loader_type fields in -Documentation/x86/boot.txt for additional information. - -============================================================== - -bootloader_version: - -x86 bootloader version - -The complete bootloader version number. In the example above, this -file will contain the value 564 = 0x234. - -See the type_of_loader and ext_loader_ver fields in -Documentation/x86/boot.txt for additional information. - -============================================================== - -callhome: - -Controls the kernel's callhome behavior in case of a kernel panic. - -The s390 hardware allows an operating system to send a notification -to a service organization (callhome) in case of an operating system panic. - -When the value in this file is 0 (which is the default behavior) -nothing happens in case of a kernel panic. If this value is set to "1" -the complete kernel oops message is send to the IBM customer service -organization in case the mainframe the Linux operating system is running -on has a service contract with IBM. - -============================================================== - -cap_last_cap - -Highest valid capability of the running kernel. Exports -CAP_LAST_CAP from the kernel. - -============================================================== - -core_pattern: - -core_pattern is used to specify a core dumpfile pattern name. -. max length 128 characters; default value is "core" -. core_pattern is used as a pattern template for the output filename; - certain string patterns (beginning with '%') are substituted with - their actual values. -. backward compatibility with core_uses_pid: - If core_pattern does not include "%p" (default does not) - and core_uses_pid is set, then .PID will be appended to - the filename. -. corename format specifiers: - %<NUL> '%' is dropped - %% output one '%' - %p pid - %u uid - %g gid - %d dump mode, matches PR_SET_DUMPABLE and - /proc/sys/fs/suid_dumpable - %s signal number - %t UNIX time of dump - %h hostname - %e executable filename (may be shortened) - %E executable path - %<OTHER> both are dropped -. If the first character of the pattern is a '|', the kernel will treat - the rest of the pattern as a command to run. The core dump will be - written to the standard input of that program instead of to a file. - -============================================================== - -core_pipe_limit: - -This sysctl is only applicable when core_pattern is configured to pipe -core files to a user space helper (when the first character of -core_pattern is a '|', see above). When collecting cores via a pipe -to an application, it is occasionally useful for the collecting -application to gather data about the crashing process from its -/proc/pid directory. In order to do this safely, the kernel must wait -for the collecting process to exit, so as not to remove the crashing -processes proc files prematurely. This in turn creates the -possibility that a misbehaving userspace collecting process can block -the reaping of a crashed process simply by never exiting. This sysctl -defends against that. It defines how many concurrent crashing -processes may be piped to user space applications in parallel. If -this value is exceeded, then those crashing processes above that value -are noted via the kernel log and their cores are skipped. 0 is a -special value, indicating that unlimited processes may be captured in -parallel, but that no waiting will take place (i.e. the collecting -process is not guaranteed access to /proc/<crashing pid>/). This -value defaults to 0. - -============================================================== - -core_uses_pid: - -The default coredump filename is "core". By setting -core_uses_pid to 1, the coredump filename becomes core.PID. -If core_pattern does not include "%p" (default does not) -and core_uses_pid is set, then .PID will be appended to -the filename. - -============================================================== - -ctrl-alt-del: - -When the value in this file is 0, ctrl-alt-del is trapped and -sent to the init(1) program to handle a graceful restart. -When, however, the value is > 0, Linux's reaction to a Vulcan -Nerve Pinch (tm) will be an immediate reboot, without even -syncing its dirty buffers. - -Note: when a program (like dosemu) has the keyboard in 'raw' -mode, the ctrl-alt-del is intercepted by the program before it -ever reaches the kernel tty layer, and it's up to the program -to decide what to do with it. - -============================================================== - -dmesg_restrict: - -This toggle indicates whether unprivileged users are prevented -from using dmesg(8) to view messages from the kernel's log buffer. -When dmesg_restrict is set to (0) there are no restrictions. When -dmesg_restrict is set set to (1), users must have CAP_SYSLOG to use -dmesg(8). - -The kernel config option CONFIG_SECURITY_DMESG_RESTRICT sets the -default value of dmesg_restrict. - -============================================================== - -domainname & hostname: - -These files can be used to set the NIS/YP domainname and the -hostname of your box in exactly the same way as the commands -domainname and hostname, i.e.: -# echo "darkstar" > /proc/sys/kernel/hostname -# echo "mydomain" > /proc/sys/kernel/domainname -has the same effect as -# hostname "darkstar" -# domainname "mydomain" - -Note, however, that the classic darkstar.frop.org has the -hostname "darkstar" and DNS (Internet Domain Name Server) -domainname "frop.org", not to be confused with the NIS (Network -Information Service) or YP (Yellow Pages) domainname. These two -domain names are in general different. For a detailed discussion -see the hostname(1) man page. - -============================================================== - -hotplug: - -Path for the hotplug policy agent. -Default value is "/sbin/hotplug". - -============================================================== - -kptr_restrict: - -This toggle indicates whether restrictions are placed on -exposing kernel addresses via /proc and other interfaces. When -kptr_restrict is set to (0), there are no restrictions. When -kptr_restrict is set to (1), the default, kernel pointers -printed using the %pK format specifier will be replaced with 0's -unless the user has CAP_SYSLOG. When kptr_restrict is set to -(2), kernel pointers printed using %pK will be replaced with 0's -regardless of privileges. - -============================================================== - -kstack_depth_to_print: (X86 only) - -Controls the number of words to print when dumping the raw -kernel stack. - -============================================================== - -l2cr: (PPC only) - -This flag controls the L2 cache of G3 processor boards. If -0, the cache is disabled. Enabled if nonzero. - -============================================================== - -modules_disabled: - -A toggle value indicating if modules are allowed to be loaded -in an otherwise modular kernel. This toggle defaults to off -(0), but can be set true (1). Once true, modules can be -neither loaded nor unloaded, and the toggle cannot be set back -to false. - -============================================================== - -msg_next_id, sem_next_id, and shm_next_id: - -These three toggles allows to specify desired id for next allocated IPC -object: message, semaphore or shared memory respectively. - -By default they are equal to -1, which means generic allocation logic. -Possible values to set are in range {0..INT_MAX}. - -Notes: -1) kernel doesn't guarantee, that new object will have desired id. So, -it's up to userspace, how to handle an object with "wrong" id. -2) Toggle with non-default value will be set back to -1 by kernel after -successful IPC object allocation. - -============================================================== - -nmi_watchdog: - -Enables/Disables the NMI watchdog on x86 systems. When the value is -non-zero the NMI watchdog is enabled and will continuously test all -online cpus to determine whether or not they are still functioning -properly. Currently, passing "nmi_watchdog=" parameter at boot time is -required for this function to work. - -If LAPIC NMI watchdog method is in use (nmi_watchdog=2 kernel -parameter), the NMI watchdog shares registers with oprofile. By -disabling the NMI watchdog, oprofile may have more registers to -utilize. - -============================================================== - -osrelease, ostype & version: - -# cat osrelease -2.1.88 -# cat ostype -Linux -# cat version -#5 Wed Feb 25 21:49:24 MET 1998 - -The files osrelease and ostype should be clear enough. Version -needs a little more clarification however. The '#5' means that -this is the fifth kernel built from this source base and the -date behind it indicates the time the kernel was built. -The only way to tune these values is to rebuild the kernel :-) - -============================================================== - -overflowgid & overflowuid: - -if your architecture did not always support 32-bit UIDs (i.e. arm, -i386, m68k, sh, and sparc32), a fixed UID and GID will be returned to -applications that use the old 16-bit UID/GID system calls, if the -actual UID or GID would exceed 65535. - -These sysctls allow you to change the value of the fixed UID and GID. -The default is 65534. - -============================================================== - -panic: - -The value in this file represents the number of seconds the kernel -waits before rebooting on a panic. When you use the software watchdog, -the recommended setting is 60. - -============================================================== - -panic_on_unrecovered_nmi: - -The default Linux behaviour on an NMI of either memory or unknown is -to continue operation. For many environments such as scientific -computing it is preferable that the box is taken out and the error -dealt with than an uncorrected parity/ECC error get propagated. - -A small number of systems do generate NMI's for bizarre random reasons -such as power management so the default is off. That sysctl works like -the existing panic controls already in that directory. - -============================================================== - -panic_on_oops: - -Controls the kernel's behaviour when an oops or BUG is encountered. - -0: try to continue operation - -1: panic immediately. If the `panic' sysctl is also non-zero then the - machine will be rebooted. - -============================================================== - -panic_on_stackoverflow: - -Controls the kernel's behavior when detecting the overflows of -kernel, IRQ and exception stacks except a user stack. -This file shows up if CONFIG_DEBUG_STACKOVERFLOW is enabled. - -0: try to continue operation. - -1: panic immediately. - -============================================================== - -perf_cpu_time_max_percent: - -Hints to the kernel how much CPU time it should be allowed to -use to handle perf sampling events. If the perf subsystem -is informed that its samples are exceeding this limit, it -will drop its sampling frequency to attempt to reduce its CPU -usage. - -Some perf sampling happens in NMIs. If these samples -unexpectedly take too long to execute, the NMIs can become -stacked up next to each other so much that nothing else is -allowed to execute. - -0: disable the mechanism. Do not monitor or correct perf's - sampling rate no matter how CPU time it takes. - -1-100: attempt to throttle perf's sample rate to this - percentage of CPU. Note: the kernel calculates an - "expected" length of each sample event. 100 here means - 100% of that expected length. Even if this is set to - 100, you may still see sample throttling if this - length is exceeded. Set to 0 if you truly do not care - how much CPU is consumed. - -============================================================== - - -pid_max: - -PID allocation wrap value. When the kernel's next PID value -reaches this value, it wraps back to a minimum PID value. -PIDs of value pid_max or larger are not allocated. - -============================================================== - -ns_last_pid: - -The last pid allocated in the current (the one task using this sysctl -lives in) pid namespace. When selecting a pid for a next task on fork -kernel tries to allocate a number starting from this one. - -============================================================== - -powersave-nap: (PPC only) - -If set, Linux-PPC will use the 'nap' mode of powersaving, -otherwise the 'doze' mode will be used. - -============================================================== - -printk: - -The four values in printk denote: console_loglevel, -default_message_loglevel, minimum_console_loglevel and -default_console_loglevel respectively. - -These values influence printk() behavior when printing or -logging error messages. See 'man 2 syslog' for more info on -the different loglevels. - -- console_loglevel: messages with a higher priority than - this will be printed to the console -- default_message_loglevel: messages without an explicit priority - will be printed with this priority -- minimum_console_loglevel: minimum (highest) value to which - console_loglevel can be set -- default_console_loglevel: default value for console_loglevel - -============================================================== - -printk_delay: - -Delay each printk message in printk_delay milliseconds - -Value from 0 - 10000 is allowed. - -============================================================== - -printk_ratelimit: - -Some warning messages are rate limited. printk_ratelimit specifies -the minimum length of time between these messages (in jiffies), by -default we allow one every 5 seconds. - -A value of 0 will disable rate limiting. - -============================================================== - -printk_ratelimit_burst: - -While long term we enforce one message per printk_ratelimit -seconds, we do allow a burst of messages to pass through. -printk_ratelimit_burst specifies the number of messages we can -send before ratelimiting kicks in. - -============================================================== - -randomize_va_space: - -This option can be used to select the type of process address -space randomization that is used in the system, for architectures -that support this feature. - -0 - Turn the process address space randomization off. This is the - default for architectures that do not support this feature anyways, - and kernels that are booted with the "norandmaps" parameter. - -1 - Make the addresses of mmap base, stack and VDSO page randomized. - This, among other things, implies that shared libraries will be - loaded to random addresses. Also for PIE-linked binaries, the - location of code start is randomized. This is the default if the - CONFIG_COMPAT_BRK option is enabled. - -2 - Additionally enable heap randomization. This is the default if - CONFIG_COMPAT_BRK is disabled. - - There are a few legacy applications out there (such as some ancient - versions of libc.so.5 from 1996) that assume that brk area starts - just after the end of the code+bss. These applications break when - start of the brk area is randomized. There are however no known - non-legacy applications that would be broken this way, so for most - systems it is safe to choose full randomization. - - Systems with ancient and/or broken binaries should be configured - with CONFIG_COMPAT_BRK enabled, which excludes the heap from process - address space randomization. - -============================================================== - -reboot-cmd: (Sparc only) - -??? This seems to be a way to give an argument to the Sparc -ROM/Flash boot loader. Maybe to tell it what to do after -rebooting. ??? - -============================================================== - -rtsig-max & rtsig-nr: - -The file rtsig-max can be used to tune the maximum number -of POSIX realtime (queued) signals that can be outstanding -in the system. - -rtsig-nr shows the number of RT signals currently queued. - -============================================================== - -sg-big-buff: - -This file shows the size of the generic SCSI (sg) buffer. -You can't tune it just yet, but you could change it on -compile time by editing include/scsi/sg.h and changing -the value of SG_BIG_BUFF. - -There shouldn't be any reason to change this value. If -you can come up with one, you probably know what you -are doing anyway :) - -============================================================== - -shmall: - -This parameter sets the total amount of shared memory pages that -can be used system wide. Hence, SHMALL should always be at least -ceil(shmmax/PAGE_SIZE). - -If you are not sure what the default PAGE_SIZE is on your Linux -system, you can run the following command: - -# getconf PAGE_SIZE - -============================================================== - -shmmax: - -This value can be used to query and set the run time limit -on the maximum shared memory segment size that can be created. -Shared memory segments up to 1Gb are now supported in the -kernel. This value defaults to SHMMAX. - -============================================================== - -shm_rmid_forced: - -Linux lets you set resource limits, including how much memory one -process can consume, via setrlimit(2). Unfortunately, shared memory -segments are allowed to exist without association with any process, and -thus might not be counted against any resource limits. If enabled, -shared memory segments are automatically destroyed when their attach -count becomes zero after a detach or a process termination. It will -also destroy segments that were created, but never attached to, on exit -from the process. The only use left for IPC_RMID is to immediately -destroy an unattached segment. Of course, this breaks the way things are -defined, so some applications might stop working. Note that this -feature will do you no good unless you also configure your resource -limits (in particular, RLIMIT_AS and RLIMIT_NPROC). Most systems don't -need this. - -Note that if you change this from 0 to 1, already created segments -without users and with a dead originative process will be destroyed. - -============================================================== - -tainted: - -Non-zero if the kernel has been tainted. Numeric values, which -can be ORed together: - - 1 - A module with a non-GPL license has been loaded, this - includes modules with no license. - Set by modutils >= 2.4.9 and module-init-tools. - 2 - A module was force loaded by insmod -f. - Set by modutils >= 2.4.9 and module-init-tools. - 4 - Unsafe SMP processors: SMP with CPUs not designed for SMP. - 8 - A module was forcibly unloaded from the system by rmmod -f. - 16 - A hardware machine check error occurred on the system. - 32 - A bad page was discovered on the system. - 64 - The user has asked that the system be marked "tainted". This - could be because they are running software that directly modifies - the hardware, or for other reasons. - 128 - The system has died. - 256 - The ACPI DSDT has been overridden with one supplied by the user - instead of using the one provided by the hardware. - 512 - A kernel warning has occurred. -1024 - A module from drivers/staging was loaded. -2048 - The system is working around a severe firmware bug. -4096 - An out-of-tree module has been loaded. - -============================================================== - -unknown_nmi_panic: - -The value in this file affects behavior of handling NMI. When the -value is non-zero, unknown NMI is trapped and then panic occurs. At -that time, kernel debugging information is displayed on console. - -NMI switch that most IA32 servers have fires unknown NMI up, for -example. If a system hangs up, try pressing the NMI switch. - -============================================================== - -watchdog_thresh: - -This value can be used to control the frequency of hrtimer and NMI -events and the soft and hard lockup thresholds. The default threshold -is 10 seconds. - -The softlockup threshold is (2 * watchdog_thresh). Setting this -tunable to zero will disable lockup detection altogether. - -============================================================== |