Re: [PATCH v2 0/3] arm64: kdump: Function supplement and performance optimization

[Leizhen (ThunderTown)]

On 2022/6/21 20:42, Zhen Lei wrote:
> 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.

Hi Catalin:
  Do you have time to review Patch 1-2? Please ignore Patch 3, because now someone has
proposed the following new approach:

https://lore.kernel.org/linux-mm/1656241815-28494-1-git-send-email-guanghuifeng@xxxxxxxxxxxxxxxxx/T/

> 
> 
> 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 (3):
>   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
>   arm64: kdump: Remove some redundant checks in map_mem()
> 
>  .../admin-guide/kernel-parameters.txt         | 10 ++-----
>  arch/arm64/mm/init.c                          | 28 +++++++++++++++++--
>  arch/arm64/mm/mmu.c                           | 25 ++++++++---------
>  3 files changed, 39 insertions(+), 24 deletions(-)
> 

-- 
Regards,
  Zhen Lei