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* Documentation: kdump: clean up the outdated descriptionBaoquan He2024-04-251-4/+4
| | | | | | | | | | | | | | | | | After commit 443cbaf9e2fd ("crash: split vmcoreinfo exporting code out from crash_core.c"), Kconfig item CRASH_CORE has gone away in kernel. Items VMCORE_INFO and CRASH_RESERVE are used instead. So clean up the outdated description about CRASH_CORE and update it accordingly. Link: https://lkml.kernel.org/r/20240329132825.1102459-3-bhe@redhat.com Signed-off-by: Baoquan He <bhe@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: WANG Xuerui <kernel@xen0n.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* x86/cpu: Detect real BSP on crash kernelsThomas Gleixner2024-02-151-5/+2
| | | | | | | | | | | | | | | | | | | | | | | When a kdump kernel is started from a crashing CPU then there is no guarantee that this CPU is the real boot CPU (BSP). If the kdump kernel tries to online the BSP then the INIT sequence will reset the machine. There is a command line option to prevent this, but in case of nested kdump kernels this is wrong. But that command line option is not required at all because the real BSP is enumerated as the first CPU by firmware. Support for the only known system which was different (Voyager) got removed long ago. Detect whether the boot CPU APIC ID is the first APIC ID enumerated by the firmware. If the first APIC ID enumerated is not matching the boot CPU APIC ID then skip registering it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240213210252.348542071@linutronix.de
* Documentation: Drop or replace remaining mentions of IA64Ard Biesheuvel2023-09-111-34/+3
| | | | | | Drop or update mentions of IA64, as appropriate. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
* docs: kdump: add scp example to write out the dump fileTiezhu Yang2022-03-231-0/+4
| | | | | | | | | | | | | | Except cp and makedumpfile, add scp example to write out the dump file. Link: https://lkml.kernel.org/r/1644324666-15947-3-git-send-email-yangtiezhu@loongson.cn Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Acked-by: Baoquan He <bhe@redhat.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Xuefeng Li <lixuefeng@loongson.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* docs: kdump: update description about sysfs file system supportTiezhu Yang2022-03-231-3/+3
| | | | | | | | | | | | | | | | | | | | | | | Patch series "Update doc and fix some issues about kdump", v2. This patch (of 5): After commit 6a108a14fa35 ("kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT"), "Configure standard kernel features (for small systems)" is not exist, we should use "Configure standard kernel features (expert users)" now. Link: https://lkml.kernel.org/r/1644324666-15947-1-git-send-email-yangtiezhu@loongson.cn Link: https://lkml.kernel.org/r/1644324666-15947-2-git-send-email-yangtiezhu@loongson.cn Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Acked-by: Baoquan He <bhe@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Xuefeng Li <lixuefeng@loongson.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Documentation: kdump: update kdump guideBaoquan He2021-06-141-61/+109
| | | | | | | | | | | | | | | | | | | | Some parts of the guide are aged, hence need be updated. 1) The backup area of the 1st 640K on X86_64 has been removed by below commits, update the description accordingly. commit 7c321eb2b843 ("x86/kdump: Remove the backup region handling") commit 6f599d84231f ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified") 2) Sort out the descripiton of "crashkernel syntax" part. 3) And some other minor cleanups. Signed-off-by: Baoquan He <bhe@redhat.com> Acked-by: Dave Young <dyoung@redhat.com> Link: https://lore.kernel.org/r/20210609083218.GB591017@MiWiFi-R3L-srv [jc: added blank line to fix added build warning] Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* docs: admin-guide: update kdump documentation due to change of crash URLlijiang2020-09-241-2/+5
| | | | | | | | | | Since crash utility has been moved to github, the original URL is no longer available. Let's update it accordingly. Suggested-by: Dave Young <dyoung@redhat.com> Signed-off-by: Lianbo Jiang <lijiang@redhat.com> Link: https://lore.kernel.org/r/a088bff5-1174-25fa-ac26-6e46795f4085@redhat.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* kernel: add panic_on_taintRafael Aquini2020-06-081-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Analogously to the introduction of panic_on_warn, this patch introduces a kernel option named panic_on_taint in order to provide a simple and generic way to stop execution and catch a coredump when the kernel gets tainted by any given flag. This is useful for debugging sessions as it avoids having to rebuild the kernel to explicitly add calls to panic() into the code sites that introduce the taint flags of interest. For instance, if one is interested in proceeding with a post-mortem analysis at the point a given code path is hitting a bad page (i.e. unaccount_page_cache_page(), or slab_bug()), a coredump can be collected by rebooting the kernel with 'panic_on_taint=0x20' amended to the command line. Another, perhaps less frequent, use for this option would be as a means for assuring a security policy case where only a subset of taints, or no single taint (in paranoid mode), is allowed for the running system. The optional switch 'nousertaint' is handy in this particular scenario, as it will avoid userspace induced crashes by writes to sysctl interface /proc/sys/kernel/tainted causing false positive hits for such policies. [akpm@linux-foundation.org: tweak kernel-parameters.txt wording] Suggested-by: Qian Cai <cai@lca.pw> Signed-off-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Cc: Dave Young <dyoung@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Bunk <bunk@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Laura Abbott <labbott@redhat.com> Cc: Jeff Mahoney <jeffm@suse.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: Takashi Iwai <tiwai@suse.de> Link: http://lkml.kernel.org/r/20200515175502.146720-1-aquini@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* docs: admin-guide: add kdump documentation into itMauro Carvalho Chehab2019-07-151-0/+534
The Kdump documentation describes procedures with admins use in order to solve issues on their systems. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>