From: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx> 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.brennan@xxxxxxxxxx> > Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx> > --- > > > 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-gpiccoli@xxxxxxxxxx/ > > 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 <mhklinux@xxxxxxxxxxx>