From: Guilherme G. Piccoli Date: Sun, 27 Oct 2024 20:36:58 +0000 (-0300) Subject: Documentation: Improve crash_kexec_post_notifiers description X-Git-Tag: v6.13-rc1~170^2~7 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7d6094e62cc0e987bab01c4c3f7e3b613fb314d2;p=thirdparty%2Fkernel%2Flinux.git Documentation: Improve crash_kexec_post_notifiers description The crash_kexec_post_notifiers description could be improved a bit, by clarifying its upsides (yes, there are some!) and be more descriptive about the downsides, specially mentioning code that enables the option unconditionally, like Hyper-V[0], PowerPC (fadump)[1] and more recently, AMD SEV-SNP[2]. [0] Commit a11589563e96 ("x86/Hyper-V: Report crash register data or kmsg before running crash kernel"). [1] Commit 06e629c25daa ("powerpc/fadump: Fix inaccurate CPU state info in vmcore generated with panic"). [2] Commit 8ef979584ea8 ("crypto: ccp: Add panic notifier for SEV/SNP firmware shutdown on kdump"). Reviewed-by: Stephen Brennan Signed-off-by: Guilherme G. Piccoli Reviewed-by: Michael Kelley Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20241027204159.985163-1-gpiccoli@igalia.com --- diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 3978fb704c53a..1dbd0b0df6fe3 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -918,12 +918,16 @@ the parameter has no effect. crash_kexec_post_notifiers - Run kdump after running panic-notifiers and dumping - kmsg. This only for the users who doubt kdump always - succeeds in any situation. - Note that this also increases risks of kdump failure, - because some panic notifiers can make the crashed - kernel more unstable. + Only jump to kdump kernel after running the panic + notifiers and dumping kmsg. This option increases + the risks of a kdump failure, since some panic + notifiers can make the crashed kernel more unstable. + In configurations where kdump may not be reliable, + running the panic notifiers could allow collecting + more data on dmesg, like stack traces from other CPUS + or extra data dumped by panic_print. Note that some + configurations enable this option unconditionally, + like Hyper-V, PowerPC (fadump) and AMD SEV-SNP. crashkernel=size[KMG][@offset[KMG]] [KNL,EARLY] Using kexec, Linux can switch to a 'crash kernel'