[U-Boot] [PATCH 1/1] efi_loader: restrict EFI_LOADER to armv7 and armv8 on ARM

[Tom Rini]

On Sun, Nov 17, 2019 at 11:00:40AM +0100, Heinrich Schuchardt wrote:

> fatload USB was reported to fail on the Sheevaplug. Debugging showed that
> this was caused by an incorrect unaligned write to memory in
> path_to_uefi().
> 
> UEFI on ARM requires that unaligned memory access is enabled.
> 
> * ARMv5 does not support unaligned access at all.
> * ARMv6 supports unaligned access when we clear the A flag and set the
>   U flag.
> * On ARMv7 unaligned access is possible when clearing the aligned flag,
>   which we do in function allow_unaligned() (arch/arm/cpu/armv7/sctlr.S).
>   For none of the other cpus in arch/arm/cpu/ we have implemented a
>   similar function.
> * ARMv8 allows unaligned access.
> 
> Let EFI_LOADER on ARM depend on SYS_CPU=armv7 or SYS_CPU=armv8.
> 
> Once we have implemented allow_unaligned() for other ARM CPUs we can add
> these to Kconfig.
> 
> Reported-by: Gray Remlin <gryrmln at gmail.com>
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>

Reviewed-by: Tom Rini <trini at konsulko.com>

-- 
Tom
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