[PATCH v3 0/2] arm64: kdump: Function supplement and performance optimization

Zhen Lei
2022-07-11T09:04:52Z

v2 --> v3:
1. Discard patch 3 in v2, a cleanup patch.

v1 --> v2:
1. Update the commit message of Patch 1, explicitly indicates that "crashkernel=X,high"
is specified but "crashkernel=Y,low" is not specified.
2. Drop Patch 4-5. Currently, focus on function integrity, performance optimization
will be considered in later versions.
3. Patch 3 is not mandatory, it's just a cleanup now, although it is a must for patch 4-5.
But to avoid subsequent duplication of effort, I'm glad it was accepted.

v1:
After the basic functions of "support reserving crashkernel above 4G on arm64
kdump"(see https://lkml.org/lkml/2022/5/6/428) are implemented, we still have
three features to be improved.
1. When crashkernel=X,high is specified but crashkernel=Y,low is not specified,
the default crash low memory size is provided.
2. For crashkernel=X without '@offset', if the low memory fails to be allocated,
fall back to reserve region from high memory(above DMA zones).
3. If crashkernel=X,high is used, page mapping is performed only for the crash
high memory, and block mapping is still used for other linear address spaces.
Compared to the previous version:
(1) For crashkernel=X[@offset], the memory above 4G is not changed to block
mapping, leave it to the next time.
(2) The implementation method is modified. Now the implementation is simpler
and clearer.

Zhen Lei (2):
arm64: kdump: Provide default size when crashkernel=Y,low is not
specified
arm64: kdump: Support crashkernel=X fall back to reserve region above
DMA zones

.../admin-guide/kernel-parameters.txt | 10 ++-----
arch/arm64/mm/init.c | 28 +++++++++++++++++--
2 files changed, 28 insertions(+), 10 deletions(-)

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2.25.1