+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@xxxxxxxxxxxxxxxxxxx) 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@xxxxxxxxxx>
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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