[RFC PATCH] ARM: Support allocating crashkernel above 4G for LPAE

[Jinjie Ruan]

On 2024/8/2 19:01, Russell King (Oracle) wrote:
> On Fri, Aug 02, 2024 at 05:25:10PM +0800, Jinjie Ruan wrote:
>> As ARM LPAE feature support accessing memory beyond the 4G limit, define
>> HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH macro to support reserving crash
>> memory above 4G for ARM32 LPAE.
>>
>> No test because there is no LPAE ARM32 hardware.
> 
> Why are you submitting patches for features you can't test?
> 
> I'm not going to apply this without it being properly tested, because I
> don't believe that this will work in the generic case.
> 
> If the crash kernel is located in memory outside of the lower 4GiB of
> address space, and there is no alias within physical address space
> for that memory, then there is *no* *way* for such a kernel to boot.

I'm sorry that I released this patch without testing it. I actually
intended to bring up this issue for discussion. If anyone has the
environment to test it, that would be great. In the meantime, we could
have a discussion on the significance and relevance of this approach.

> 
> So, right now I believe this patch to be *fundamentally* wrong.
>