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    SubjectRe: [PATCH v7 0/4] support reserving crashkernel above 4G on arm64 kdump
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    Hi all,

    Friendly ping...

    On 2019/12/23 23:23, Chen Zhou wrote:
    > 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 required, 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 [v6]
    > - Fix build errors reported by kbuild test robot.
    >
    > 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
    > [v6]: https://lkml.org/lkml/2019/8/30/142
    >
    > 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/kernel/setup.c | 8 ++-
    > arch/arm64/mm/init.c | 61 ++++++++++++++++-
    > arch/x86/kernel/setup.c | 62 ++----------------
    > include/linux/crash_core.h | 3 +
    > include/linux/kexec.h | 2 -
    > kernel/crash_core.c | 87 +++++++++++++++++++++++++
    > kernel/kexec_core.c | 17 -----
    > 9 files changed, 183 insertions(+), 82 deletions(-)
    >

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