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/r/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
