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

[Masayoshi Mizuma <msys.mizuma@gmail.com>]

On Wed, Dec 04, 2019 at 06:17:59PM +0000, James Morse wrote:
> 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

Thanks a lot! It worked and the issue is gone with Ard's patch and
the linaro kexec (arm64/resv_mem branch).

Ard, please feel free to add:

	Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>

> 
> 
> > 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.
 
I used the kexec on the top of master branch:
git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git

Should we use the linaro kexec for aarch64 machine?
Or will the arm64/resv_mem branch be merged to the kexec on
git.kernel.org...?

Thanks!
Masa