[PATCH v21 3/5] arm64: kdump: reimplement crashkernel=X

[Baoquan He]

On 02/27/22 at 11:07am, Zhen Lei wrote:
> From: Chen Zhou <chenzhou10 at huawei.com>
> 
> 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. If reserving crashkernel above 4G, in this case, crash dump
> kernel will boot failure because there is no low memory available
              ~~ change it to "get boot failure" or "fail to boot"
> for allocation.
> 
> To solve these issues, change the behavior of crashkernel=X and
> introduce crashkernel=X,[high,low]. crashkernel=X tries low allocation
> in DMA zone, and fall back to high allocation if it fails.
> We can also use "crashkernel=X,high" to select a region above DMA zone,
> which also tries to allocate at least 256M in DMA zone automatically.
> "crashkernel=Y,low" can be used to allocate specified size low memory.
> 
> Signed-off-by: Chen Zhou <chenzhou10 at huawei.com>
> Co-developed-by: Zhen Lei <thunder.leizhen at huawei.com>
> Signed-off-by: Zhen Lei <thunder.leizhen at huawei.com>