linux-kernel - [PATCH V2] Documentation: Improve crash_kexec_post

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Message-ID: <20240830182219.485065-1-gpiccoli@igalia.com>
Date: Fri, 30 Aug 2024 15:21:00 -0300
From: "Guilherme G. Piccoli" <gpiccoli@...lia.com>
To: kexec@...ts.infradead.org,
	linux-doc@...r.kernel.org
Cc: bhe@...hat.com,
	vgoyal@...hat.com,
	dyoung@...hat.com,
	corbet@....net,
	linux-kernel@...r.kernel.org,
	linux-debuggers@...r.kernel.org,
	stephen.s.brennan@...cle.com,
	kernel@...ccoli.net,
	kernel-dev@...lia.com,
	"Guilherme G. Piccoli" <gpiccoli@...lia.com>
Subject: [PATCH V2] Documentation: Improve crash_kexec_post_notifiers description

Be more clear about the downsides, the upsides (yes, there are some!)
and about code that unconditionally sets that.

Reviewed-by: Stephen Brennan <stephen.s.brennan@...cle.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@...lia.com>

---

V2: Some wording improvements from Stephen, thanks!
Also added his review tag.

V1 link: https://lore.kernel.org/r/20240830140401.458542-1-gpiccoli@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 efc52ddc6864..351730108c58 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -913,12 +913,16 @@
 			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 the
+			configurations where kdump may not be reliable,
+			running the panic notifiers can allow collecting more
+			data on dmesg, like stack traces from other CPUS or
+			extra data dumped by panic_print. Notice that some
+			code enables this option unconditionally, like
+			Hyper-V, PowerPC (fadump) and AMD SEV.
 
 	crashkernel=size[KMG][@offset[KMG]]
 			[KNL,EARLY] Using kexec, Linux can switch to a 'crash kernel'
-- 
2.46.0