From: Guilherme G. Piccoli <gpicc...@igalia.com> Sent: Sunday, October 27, 2024
1:37 PM
>
> 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 <stephen.s.bren...@oracle.com>
> Signed-off-by: Guilherme G. Piccoli <gpicc...@igalia.com>
> ---
>
>
> V4:
> * s/AMD SEV/AMD SEV-SNP/ for better clarity, since there are more variants
> of AMD SEV - thanks a lot Michael Kelley for the good explanation.
>
> V3 link, including interesting clarifications about AMD SEV variants, by
> Michael:
> https://lore.kernel.org/all/20241025162042.905104-1-gpicc...@igalia.com/
>
> Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index 3978fb704c53..1dbd0b0df6fe 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'
> --
> 2.46.2
Reviewed-by: Michael Kelley <mhkli...@outlook.com>
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