Re: [PATCH] efi/memreserve: register reservations as 'reserved' in /proc/iomem

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Hi Masa,

On 04/12/2019 17:17, Masayoshi Mizuma wrote:
> Thank you for sending the patch, but unfortunately it doesn't work for the issue...
> 
> After applied your patch, the LPI tables are marked as reserved in
> /proc/iomem like as:
> 
> 80300000-a1fdffff : System RAM
>   80480000-8134ffff : Kernel code
>   81350000-817bffff : reserved
>   817c0000-82acffff : Kernel data
>   830f0000-830fffff : reserved # Property table
>   83480000-83480fff : reserved # Pending table
>   83490000-8349ffff : reserved # Pending table
> 
> However, kexec tries to allocate memory from System RAM, it doesn't care
> the reserved in System RAM.

> I'm not sure why kexec doesn't care the reserved in System RAM, however,

Hmm, we added these to fix a problem with the UEFI memory map, and more recently ACPI
tables being overwritten by kexec.

Which version of kexec-tools are you using? Could you try:
https://git.linaro.org/people/takahiro.akashi/kexec-tools.git/commit/?h=arm64/resv_mem


> if the kexec behaivor is right, the LPI tables should not belong to
> System RAM.

> Like as:
> 
> 80300000-830effff : System RAM
>   80480000-8134ffff : Kernel code
>   81350000-817bffff : reserved
>   817c0000-82acffff : Kernel data
> 830f0000-830fffff : reserved # Property table
> 83480000-83480fff : reserved # Pending table
> 83490000-8349ffff : reserved # Pending table
> 834a0000-a1fdffff : System RAM
> 
> I don't have ideas to separete LPI tables from System RAM... so I tried
> to add a new file to inform the LPI tables to userspace.

This is how 'nomap' memory appears, we carve it out of System RAM. A side effect of this
is kdump can't touch it, as you've told it this isn't memory.

As these tables are memory, mapped by the linear map, I think Ard's patch is the right
thing to do ... I suspect your kexec-tools doesn't have those patches from Akashi to make
it honour all second level entries.


Thanks,

James



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