linux/fs/proc/Kconfig

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config PROC_FS
bool "/proc file system support" if EXPERT
default y
help
This is a virtual file system providing information about the status
of the system. "Virtual" means that it doesn't take up any space on
your hard disk: the files are created on the fly by the kernel when
you try to access them. Also, you cannot read the files with older
version of the program less: you need to use more or cat.
It's totally cool; for example, "cat /proc/interrupts" gives
information about what the different IRQs are used for at the moment
(there is a small number of Interrupt ReQuest lines in your computer
that are used by the attached devices to gain the CPU's attention --
often a source of trouble if two devices are mistakenly configured
to use the same IRQ). The program procinfo to display some
information about your system gathered from the /proc file system.
Before you can use the /proc file system, it has to be mounted,
meaning it has to be given a location in the directory hierarchy.
That location should be /proc. A command such as "mount -t proc proc
/proc" or the equivalent line in /etc/fstab does the job.
The /proc file system is explained in the file
<file:Documentation/filesystems/proc.txt> and on the proc(5) manpage
("man 5 proc").
This option will enlarge your kernel by about 67 KB. Several
programs depend on this, so everyone should say Y here.
config PROC_KCORE
bool "/proc/kcore support" if !ARM
depends on PROC_FS && MMU
help
Provides a virtual ELF core file of the live kernel. This can
be read with gdb and other ELF tools. No modifications can be
made using this mechanism.
config PROC_VMCORE
bool "/proc/vmcore support"
depends on PROC_FS && CRASH_DUMP
default y
help
Exports the dump image of crashed kernel in ELF format.
config PROC_SYSCTL
bool "Sysctl support (/proc/sys)" if EXPERT
depends on PROC_FS
select SYSCTL
default y
---help---
The sysctl interface provides a means of dynamically changing
certain kernel parameters and variables on the fly without requiring
a recompile of the kernel or reboot of the system. The primary
interface is through /proc/sys. If you say Y here a tree of
modifiable sysctl entries will be generated beneath the
/proc/sys directory. They are explained in the files
in <file:Documentation/sysctl/>. Note that enabling this
option will enlarge the kernel by at least 8 KB.
As it is generally a good thing, you should say Y here unless
building a kernel for install/rescue disks or your system is very
limited in memory.
config PROC_PAGE_MONITOR
default y
depends on PROC_FS && MMU
bool "Enable /proc page monitoring" if EXPERT
help
Various /proc files exist to monitor process memory utilization:
/proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
/proc/kpagecount, and /proc/kpageflags. Disabling these
interfaces will reduce the size of the kernel by approximately 4kb.
fs, proc: introduce CONFIG_PROC_CHILDREN Commit 818411616baf ("fs, proc: introduce /proc/<pid>/task/<tid>/children entry") introduced the children entry for checkpoint restore and the file is only available on kernels configured with CONFIG_EXPERT and CONFIG_CHECKPOINT_RESTORE. This is available in most distributions (Fedora, Debian, Ubuntu, CoreOS) because they usually enable CONFIG_EXPERT and CONFIG_CHECKPOINT_RESTORE. But Arch does not enable CONFIG_EXPERT or CONFIG_CHECKPOINT_RESTORE. However, the children proc file is useful outside of checkpoint restore. I would like to use it in rkt. The rkt process exec() another program it does not control, and that other program will fork()+exec() a child process. I would like to find the pid of the child process from an external tool without iterating in /proc over all processes to find which one has a parent pid equal to rkt. This commit introduces CONFIG_PROC_CHILDREN and makes CONFIG_CHECKPOINT_RESTORE select it. This allows enabling /proc/<pid>/task/<tid>/children without needing to enable CONFIG_CHECKPOINT_RESTORE and CONFIG_EXPERT. Alban tested that /proc/<pid>/task/<tid>/children is present when the kernel is configured with CONFIG_PROC_CHILDREN=y but without CONFIG_CHECKPOINT_RESTORE Signed-off-by: Iago López Galeiras <iago@endocode.com> Tested-by: Alban Crequy <alban@endocode.com> Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <keescook@chromium.org> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Serge Hallyn <serge.hallyn@canonical.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Djalal Harouni <djalal@endocode.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-26 00:00:57 +02:00
config PROC_CHILDREN
bool "Include /proc/<pid>/task/<tid>/children file"
default n
help
Provides a fast way to retrieve first level children pids of a task. See
<file:Documentation/filesystems/proc.txt> for more information.
Say Y if you are running any user-space software which takes benefit from
this interface. For example, rkt is such a piece of software.