Messages in this thread | | | Subject | Re: [PATCH 0/4] support reserving crashkernel above 4G on arm64 kdump | From | Bhupesh Sharma <> | Date | Wed, 15 May 2019 10:36:24 +0530 |
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+Cc kexec-list.
Hi Chen,
I think we are still in the quiet period of the merge cycle, but this is a change which will be useful for systems like HPE Apollo where we are looking at reserving crashkernel across a larger range.
Some comments inline and in respective patch threads..
On 05/07/2019 09:20 AM, Chen Zhou wrote: > This patch series enable reserving crashkernel on high memory in arm64.
Please fix the patch subject, it should be v5. Also please Cc the kexec-list (kexec@lists.infradead.org) for future versions to allow wider review of the patchset.
> We use crashkernel=X to reserve crashkernel below 4G, which will fail > when there is no enough memory. Currently, crashkernel=Y@X can be used > to reserve crashkernel above 4G, in this case, if swiotlb or DMA buffers > are requierd, capture kernel will boot failure because of no low memory.
... ^^ required
s/capture kernel will boot failure because of no low memory./capture kernel boot will fail because there is no low memory available for allocation.
> When crashkernel is reserved above 4G in memory, kernel should reserve > some amount of low memory for swiotlb and some DMA buffers. So there may > be two crash kernel regions, one is below 4G, the other is above 4G. Then > Crash dump kernel reads more than one crash kernel regions via a dtb > property under node /chosen, > linux,usable-memory-range = <BASE1 SIZE1 [BASE2 SIZE2]>.
Please use consistent naming for the second kernel, better to use crash dump kernel.
I have tested this on my HPE Apollo machine and with crashkernel=886M,high syntax, I can get the board to reserve a larger memory range for the crashkernel (i.e. 886M):
# dmesg | grep -i crash [ 0.000000] kexec_core: Reserving 256MB of low memory at 3560MB for crashkernel (System low RAM: 2029MB) [ 0.000000] crashkernel reserved: 0x0000000bc5a00000 - 0x0000000bfd000000 (886 MB)
kexec/kdump can also work also work fine on the board.
So, with the changes suggested in this cover letter and individual patches, please feel free to add:
Reviewed-and-Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Thanks, Bhupesh
> Besides, we need to modify kexec-tools: > arm64: support more than one crash kernel regions(see [1]) > > I post this patch series about one month ago. The previous changes and > discussions can be retrived from: > > Changes since [v4] > - reimplement memblock_cap_memory_ranges for multiple ranges by Mike. > > Changes since [v3] > - Add memblock_cap_memory_ranges back for multiple ranges. > - Fix some compiling warnings. > > Changes since [v2] > - Split patch "arm64: kdump: support reserving crashkernel above 4G" as > two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate > patch. > > Changes since [v1]: > - Move common reserve_crashkernel_low() code into kernel/kexec_core.c. > - Remove memblock_cap_memory_ranges() i added in v1 and implement that > in fdt_enforce_memory_region(). > There are at most two crash kernel regions, for two crash kernel regions > case, we cap the memory range [min(regs[*].start), max(regs[*].end)] > and then remove the memory range in the middle. > > [1]: http://lists.infradead.org/pipermail/kexec/2019-April/022792.html > [v1]: https://lkml.org/lkml/2019/4/2/1174 > [v2]: https://lkml.org/lkml/2019/4/9/86 > [v3]: https://lkml.org/lkml/2019/4/9/306 > [v4]: https://lkml.org/lkml/2019/4/15/273 > > Chen Zhou (3): > x86: kdump: move reserve_crashkernel_low() into kexec_core.c > arm64: kdump: support reserving crashkernel above 4G > kdump: update Documentation about crashkernel on arm64 > > Mike Rapoport (1): > memblock: extend memblock_cap_memory_range to multiple ranges > > Documentation/admin-guide/kernel-parameters.txt | 6 +-- > arch/arm64/include/asm/kexec.h | 3 ++ > arch/arm64/kernel/setup.c | 3 ++ > arch/arm64/mm/init.c | 72 +++++++++++++++++++------ > arch/x86/include/asm/kexec.h | 3 ++ > arch/x86/kernel/setup.c | 66 +++-------------------- > include/linux/kexec.h | 5 ++ > include/linux/memblock.h | 2 +- > kernel/kexec_core.c | 56 +++++++++++++++++++ > mm/memblock.c | 44 +++++++-------- > 10 files changed, 157 insertions(+), 103 deletions(-) >
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