c6c405336b
Since commit 2724273e8f ("vmcore: add API to collect hardware dump in
second kernel"), drivers are allowed to add device related dump data to
vmcore as they want by using the device dump API. This has a potential
issue, the data is stored in memory, drivers may append too much data
and use too much memory. The vmcore is typically used in a kdump kernel
which runs in a pre-reserved small chunk of memory. So as a result it
will make kdump unusable at all due to OOM issues.
So introduce new 'novmcoredd' command line option. User can disable
device dump to reduce memory usage. This is helpful if device dump is
using too much memory, disabling device dump could make sure a regular
vmcore without device dump data is still available.
[akpm@linux-foundation.org: tweak documentation]
[akpm@linux-foundation.org: vmcore.c needs moduleparam.h]
Link: http://lkml.kernel.org/r/20190528111856.7276-1-kasong@redhat.com
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Cc: "David S . Miller" <davem@davemloft.net>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
106 lines
4.1 KiB
Plaintext
106 lines
4.1 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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config PROC_FS
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bool "/proc file system support" if EXPERT
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default y
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help
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This is a virtual file system providing information about the status
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of the system. "Virtual" means that it doesn't take up any space on
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your hard disk: the files are created on the fly by the kernel when
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you try to access them. Also, you cannot read the files with older
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version of the program less: you need to use more or cat.
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It's totally cool; for example, "cat /proc/interrupts" gives
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information about what the different IRQs are used for at the moment
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(there is a small number of Interrupt ReQuest lines in your computer
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that are used by the attached devices to gain the CPU's attention --
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often a source of trouble if two devices are mistakenly configured
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to use the same IRQ). The program procinfo to display some
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information about your system gathered from the /proc file system.
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Before you can use the /proc file system, it has to be mounted,
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meaning it has to be given a location in the directory hierarchy.
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That location should be /proc. A command such as "mount -t proc proc
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/proc" or the equivalent line in /etc/fstab does the job.
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The /proc file system is explained in the file
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<file:Documentation/filesystems/proc.txt> and on the proc(5) manpage
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("man 5 proc").
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This option will enlarge your kernel by about 67 KB. Several
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programs depend on this, so everyone should say Y here.
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config PROC_KCORE
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bool "/proc/kcore support" if !ARM
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depends on PROC_FS && MMU
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select CRASH_CORE
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help
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Provides a virtual ELF core file of the live kernel. This can
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be read with gdb and other ELF tools. No modifications can be
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made using this mechanism.
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config PROC_VMCORE
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bool "/proc/vmcore support"
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depends on PROC_FS && CRASH_DUMP
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default y
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help
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Exports the dump image of crashed kernel in ELF format.
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config PROC_VMCORE_DEVICE_DUMP
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bool "Device Hardware/Firmware Log Collection"
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depends on PROC_VMCORE
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default n
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help
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After kernel panic, device drivers can collect the device
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specific snapshot of their hardware or firmware before the
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underlying devices are initialized in crash recovery kernel.
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Note that the device driver must be present in the crash
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recovery kernel's initramfs to collect its underlying device
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snapshot.
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If you say Y here, the collected device dumps will be added
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as ELF notes to /proc/vmcore. You can still disable device
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dump using the kernel command line option 'novmcoredd'.
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config PROC_SYSCTL
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bool "Sysctl support (/proc/sys)" if EXPERT
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depends on PROC_FS
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select SYSCTL
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default y
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---help---
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The sysctl interface provides a means of dynamically changing
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certain kernel parameters and variables on the fly without requiring
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a recompile of the kernel or reboot of the system. The primary
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interface is through /proc/sys. If you say Y here a tree of
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modifiable sysctl entries will be generated beneath the
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/proc/sys directory. They are explained in the files
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in <file:Documentation/sysctl/>. Note that enabling this
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option will enlarge the kernel by at least 8 KB.
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As it is generally a good thing, you should say Y here unless
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building a kernel for install/rescue disks or your system is very
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limited in memory.
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config PROC_PAGE_MONITOR
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default y
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depends on PROC_FS && MMU
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bool "Enable /proc page monitoring" if EXPERT
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help
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Various /proc files exist to monitor process memory utilization:
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/proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
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/proc/kpagecount, and /proc/kpageflags. Disabling these
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interfaces will reduce the size of the kernel by approximately 4kb.
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config PROC_CHILDREN
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bool "Include /proc/<pid>/task/<tid>/children file"
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default n
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help
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Provides a fast way to retrieve first level children pids of a task. See
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<file:Documentation/filesystems/proc.txt> for more information.
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Say Y if you are running any user-space software which takes benefit from
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this interface. For example, rkt is such a piece of software.
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config PROC_PID_ARCH_STATUS
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def_bool n
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depends on PROC_FS
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