[PATCH v2 2/2] efi: arm-stub: Round up FDT allocation to mapping size

[Ard Biesheuvel]

On 10 February 2017 at 00:40, Ruigrok, Richard <rruigrok at codeaurora.org> wrote:
>
>
> On 2/9/2017 2:42 PM, Ard Biesheuvel wrote:
>
> The FDT is mapped via a fixmap entry that is at least 2 MB in size and
> 2 MB aligned on 4 KB page size kernels.
>
> On UEFI systems, the FDT allocation may share this 2 MB block with a
> reserved region, or another memory region that we should never map,
> unless we account for this in the size of the allocation (the alignment
> is already 2 MB)
>
> So instead of taking guesses at the needed space, simply allocate 2 MB
> immediately. The allocation will be recorded as a EFI_LOADER_DATA, and
> the kernel only memblock_reserve()'s the actual size of the FDT, so the
> unused space will be released to the kernel.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---
>  arch/arm64/include/asm/efi.h       |  1 +
>  drivers/firmware/efi/libstub/fdt.c | 57 +++++++++-----------
>  2 files changed, 25 insertions(+), 33 deletions(-)
>
[..]
> Tested successfully on our QDT2400 system on which we were seeing a failure
> to allocate memory for initrd.
>
> Tested-by: Richard Ruigrok <rruigrok at codeaurora.org>
>

Thanks