Messages in this thread | | | Date | Tue, 8 Jun 2021 22:24:32 +0800 | From | Baoquan He <> | Subject | Re: [PATCH] crash_core, vmcoreinfo: Append 'SECTION_SIZE_BITS' to vmcoreinfo |
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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.
> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com> > Cc: Bhupesh Sharma <bhupesh.sharma@linaro.org> > Cc: Kazuhito Hagio <k-hagio@ab.jp.nec.com> > Cc: Dave Young <dyoung@redhat.com> > Cc: Baoquan He <bhe@redhat.com> > Cc: Boris Petkov <bp@alien8.de> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: James Morse <james.morse@arm.com> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Michael Ellerman <mpe@ellerman.id.au> > Cc: Paul Mackerras <paulus@samba.org> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Cc: Dave Anderson <anderson@redhat.com> > Cc: linuxppc-dev@lists.ozlabs.org > Cc: linux-kernel@vger.kernel.org > Cc: kexec@lists.infradead.org > Cc: x86@kernel.org > Cc: linux-arm-kernel@lists.infradead.org
Add the discussion of the original thread in kexec ML for reference: http://lists.infradead.org/pipermail/kexec/2021-June/022676.html
This looks good to me.
Acked-by: Baoquan He <bhe@redhat.com>
> --- > kernel/crash_core.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index 825284baaf46..684a6061a13a 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -464,6 +464,7 @@ static int __init crash_save_vmcoreinfo_init(void) > VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS); > VMCOREINFO_STRUCT_SIZE(mem_section); > VMCOREINFO_OFFSET(mem_section, section_mem_map); > + VMCOREINFO_NUMBER(SECTION_SIZE_BITS); > VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS); > #endif > VMCOREINFO_STRUCT_SIZE(page); > -- > 2.29.2 >
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