8d470a45d1
Currently the "panic_print" parameter/sysctl allows some interesting debug information to be printed during a panic event. This is useful for example in cases the user cannot kdump due to resource limits, or if the user collects panic logs in a serial output (or pstore) and prefers a fast reboot instead of a kdump. Happens that currently there's no way to see all CPUs backtraces in a panic using "panic_print" on architectures that support that. We do have "oops_all_cpu_backtrace" sysctl, but although partially overlapping in the functionality, they are orthogonal in nature: "panic_print" is a panic tuning (and we have panics without oopses, like direct calls to panic() or maybe other paths that don't go through oops_enter() function), and the original purpose of "oops_all_cpu_backtrace" is to provide more information on oopses for cases in which the users desire to continue running the kernel even after an oops, i.e., used in non-panic scenarios. So, we hereby introduce an additional bit for "panic_print" to allow dumping the CPUs backtraces during a panic event. Link: https://lkml.kernel.org/r/20211109202848.610874-3-gpiccoli@igalia.com Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> Reviewed-by: Feng Tang <feng.tang@intel.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Samuel Iglesias Gonsalvez <siglesias@igalia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.