Re: [PATCH] crash_core, vmcoreinfo: Append 'SECTION_SIZE_BITS' to vmcoreinfo
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2021-06-08 21:14:14
Also in:
kexec, linuxppc-dev, lkml
On Tue, 8 Jun 2021 22:24:32 +0800 Baoquan He [off-list ref] wrote:
On 06/08/21 at 06:33am, Pingfan Liu wrote:quoted
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 <redacted>
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? _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel