linux-kernel - Re: [PATCH v12 7/7] x86/crash: Add x86 crash hotplug support

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Date:   Sat, 29 Oct 2022 00:19:36 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Eric DeVolder <eric.devolder@...cle.com>
Cc:     Baoquan He <bhe@...hat.com>, david@...hat.com,
        Oscar Salvador <osalvador@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        kexec@...ts.infradead.org, ebiederm@...ssion.com,
        dyoung@...hat.com, vgoyal@...hat.com, tglx@...utronix.de,
        mingo@...hat.com, dave.hansen@...ux.intel.com, hpa@...or.com,
        nramas@...ux.microsoft.com, thomas.lendacky@....com,
        robh@...nel.org, efault@....de, rppt@...nel.org,
        sourabhjain@...ux.ibm.com, linux-mm@...ck.org
Subject: Re: [PATCH v12 7/7] x86/crash: Add x86 crash hotplug support

On Fri, Oct 28, 2022 at 04:22:54PM -0500, Eric DeVolder wrote:
> /*
>  * For the kexec_file_load() syscall path, specify the maximum number of
>  * memory regions that the elfcorehdr buffer/segment can accommodate.
>  * These regions are obtained via walk_system_ram_res(); eg. the
>  * 'System RAM' entries in /proc/iomem.
>  * This value is combined with NR_CPUS and multiplied by sizeof(Elf64_Phdr)

NR_CPUS_DEFAULT

>  * to determine the final elfcorehdr memory buffer/segment size.
>  * The value 8192, for example, covers a (sparsely populated) 1TiB system
>  * consisting of 128MiB memblock size, while resulting in an elfcorehdr
>  * memory buffer/segment size under 1MiB.

... and it is a sane choice trying to accomodate both actual baremetal
and VM configurations."

Yeah, it's a good start.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette