linux-kernel - Re: [PATCH V5 2/6] Add shared update

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Date:	Mon, 02 Dec 2013 09:56:25 -0500
From:	Mark Salter <msalter@...hat.com>
To:	Matt Fleming <matt@...sole-pimps.org>
Cc:	Roy Franz <roy.franz@...aro.org>, linux-kernel@...r.kernel.org,
	linux-efi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	matt.fleming@...el.com, linux@....linux.org.uk,
	leif.lindholm@...aro.org, grant.likely@...aro.org,
	dave.martin@....com, patches@...aro.org
Subject: Re: [PATCH V5 2/6] Add shared update_fdt() function for ARM/ARM64

On Fri, 2013-11-29 at 11:30 +0000, Matt Fleming wrote:
> >       /*
> >        * Add an additional efi_memory_desc_t because we're doing an
> >        * allocation which may be in a new descriptor region.
> > +      * We allocate as EFI_RUNTIME_SERVICES_DATA since this is what
> > +      * we want for when we pass the memory map to the kernel.  This
> > +      * function is also used to get the memory map for other uses,
> > +      * but is always freed by the stub so the allocation type
> > +      * doesn't matter.
> >        */
> >       *map_size += sizeof(*m);
> >       status = efi_call_phys3(sys_table_arg->boottime->allocate_pool,
> > -                             EFI_LOADER_DATA, *map_size, (void **)&m);
> > +                             EFI_RUNTIME_SERVICES_DATA, *map_size,
> > +                             (void **)&m);
> >       if (status != EFI_SUCCESS)
> >               goto fail;
>   
> 
> OK, this needs a stronger justification. Presumably the reason for this
> change is that you want the allocation to hang around once the kernel is
> running? We have this problem on x86 and it's solved by reserving the
> memory early in the kernel, e.g. memblock_reserve().
> EFI_RUNTIME_SERVICES_DATA is for firmware use, not for kernel data.
> 

Yeah, arm64 reserves it and is okay with it being EFI_LOADER_DATA.

--Mark


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