linux-kernel - Re: [PATCH] crash: Default to CRASH_DUMP=n when support for it is unlikely

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Message-ID: <Zs2WBgtADYxzVMyt@MiWiFi-R3L-srv>
Date: Tue, 27 Aug 2024 17:01:58 +0800
From: Baoquan He <bhe@...hat.com>
To: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>,
	Dave Vasilevsky <dave@...ilevsky.ca>, linuxppc-dev@...ts.ozlabs.org,
	linux-sh@...r.kernel.org, mpe@...erman.id.au,
	kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Reimar Döffinger <Reimar.Doeffinger@....de>
Subject: Re: [PATCH] crash: Default to CRASH_DUMP=n when support for it is
 unlikely

On 08/27/24 at 08:37am, John Paul Adrian Glaubitz wrote:
> On Tue, 2024-08-27 at 14:22 +0800, Baoquan He wrote:
> > About why it's enabled by default, as Michael has explained in another
> > thread, distros usualy needs to enable it by default because vmcore
> > dumping is a very important feature on servers, even guest instances. 
> > Even though kdump codes are enabled to built in, not providing
> > crashkernel= value won't make vmcore dumping take effect, it won't cost
> > system resources in that case.
> 
> OK, thanks for the explanation. But as we have found out in the mean time,
> the assumption was wrong to enable it by default for all architectures as
> some architectures cannot boot a crash dump kernel with their default bootloader
> but only through kexec.
> 
> Can we have a follow-up patch to disable crash dump kernels where they're
> not needed? I mean, not every platform supported by Linux is obviously a
> x86-based or POWER-based server.

Yes, while isn't Dave's patch a good one to fix it? In Dave's patch, the
default enabling of CRASH_DUMP has been taken off, change to rely on
ARCH_DEFAULT_CRASH_DUMP provided by each arch.

 config CRASH_DUMP
        bool "kernel crash dumps"
-       default y
+       default ARCH_DEFAULT_CRASH_DUMP