Messages in this thread | | | Date | Tue, 8 Jun 2021 14:14:10 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] crash_core, vmcoreinfo: Append 'SECTION_SIZE_BITS' to vmcoreinfo |
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On Tue, 8 Jun 2021 22:24:32 +0800 Baoquan He <bhe@redhat.com> wrote:
> On 06/08/21 at 06:33am, Pingfan Liu wrote: > > As mentioned in kernel commit 1d50e5d0c505 ("crash_core, vmcoreinfo: > > Append 'MAX_PHYSMEM_BITS' to vmcoreinfo"), SECTION_SIZE_BITS in the > > formula: > > #define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS) > > > > Besides SECTIONS_SHIFT, SECTION_SIZE_BITS is also used to calculate > > PAGES_PER_SECTION in makedumpfile just like kernel. > > > > Unfortunately, this arch-dependent macro SECTION_SIZE_BITS changes, e.g. > > recently in kernel commit f0b13ee23241 ("arm64/sparsemem: reduce > > SECTION_SIZE_BITS"). But user space wants a stable interface to get this > > info. Such info is impossible to be deduced from a crashdump vmcore. > > Hence append SECTION_SIZE_BITS to vmcoreinfo. > > ... > > Add the discussion of the original thread in kexec ML for reference: > http://lists.infradead.org/pipermail/kexec/2021-June/022676.html
I added a Link: for this.
> This looks good to me. > > Acked-by: Baoquan He <bhe@redhat.com>
I'm thinking we should backport this at least to Fixes:f0b13ee23241. But perhaps it's simpler to just backport it as far as possible, so I added a bare cc:stable with no Fixes:. Thoughts?
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