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SubjectRe: [PATCH v6 0/4] support reserving crashkernel above 4G on arm64 kdump
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Hi all,

Friendly ping...

On 2019/8/30 15:11, Chen Zhou wrote:
> I am busy with other things, so it was a long time before this version was
> released.
>
> This patch series enable reserving crashkernel above 4G in arm64.
>
> There are following issues in arm64 kdump:
> 1. We use crashkernel=X to reserve crashkernel below 4G, which will fail
> when there is no enough low memory.
> 2. Currently, crashkernel=Y@X can be used to reserve crashkernel above 4G,
> in this case, if swiotlb or DMA buffers are requierd, crash dump kernel
> will boot failure because there is no low memory available for allocation.
>
> To solve these issues, introduce crashkernel=X,low to reserve specified
> size low memory.
> Crashkernel=X tries to reserve memory for the crash dump kernel under
> 4G. If crashkernel=Y,low is specified simultaneously, reserve spcified
> size low memory for crash kdump kernel devices firstly and then reserve
> memory above 4G.
>
> When crashkernel is reserved above 4G in memory, that is, crashkernel=X,low
> is specified simultaneously, kernel should reserve specified size low memory
> for crash dump kernel devices. So there may be two crash kernel regions, one
> is below 4G, the other is above 4G.
> In order to distinct from the high region and make no effect to the use of
> kexec-tools, rename the low region as "Crash kernel (low)", and add DT property
> "linux,low-memory-range" to crash dump kernel's dtb to pass the low region.
>
> Besides, we need to modify kexec-tools:
> arm64: kdump: add another DT property to crash dump kernel's dtb(see [1])
>
> The previous changes and discussions can be retrieved from:
>
> Changes since [v5]
> - Move reserve_crashkernel_low() into kernel/crash_core.c.
> - Delete crashkernel=X,high.
> - Modify crashkernel=X,low.
> If crashkernel=X,low is specified simultaneously, reserve spcified size low
> memory for crash kdump kernel devices firstly and then reserve memory above 4G.
> In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then
> pass to crash dump kernel by DT property "linux,low-memory-range".
> - Update Documentation/admin-guide/kdump/kdump.rst.
>
> 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-August/023569.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
> [v5]: https://lkml.org/lkml/2019/5/6/1360
>
> Chen Zhou (4):
> x86: kdump: move reserve_crashkernel_low() into crash_core.c
> arm64: kdump: reserve crashkenel above 4G for crash dump kernel
> arm64: kdump: add memory for devices by DT property, low-memory-range
> kdump: update Documentation about crashkernel on arm64
>
> Documentation/admin-guide/kdump/kdump.rst | 13 ++++-
> Documentation/admin-guide/kernel-parameters.txt | 12 ++++-
> arch/arm64/include/asm/kexec.h | 3 ++
> arch/arm64/kernel/setup.c | 8 ++-
> arch/arm64/mm/init.c | 61 +++++++++++++++++++++--
> arch/x86/include/asm/kexec.h | 3 ++
> arch/x86/kernel/setup.c | 65 +++----------------------
> include/linux/crash_core.h | 4 ++
> include/linux/kexec.h | 1 -
> kernel/crash_core.c | 65 +++++++++++++++++++++++++
> 10 files changed, 168 insertions(+), 67 deletions(-)
>

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