[U-Boot] [U-Boot,v3] efi_loader: Reserve unaccessible memory

[Alexander Graf]

> On some systems, not all RAM may be usable within U-Boot. Maybe the
> memory maps are incomplete, maybe it's used as workaround for broken
> DMA. But whatever the reason may be, a platform can say that it does
> not wish to have its RAM accessed above a certain address by defining
> board_get_usable_ram_top().
> 
> In the efi_loader world, we ignored that hint, mostly because very few
> boards actually have real restrictions around this.
> 
> So let's honor the board's wish to not access high addresses during
> boot time. The best way to do so is by indicating the respective pages
> as "allocated by firmware". That way, Operating Systems will still
> use the pages after boot, but before boot no allocation will use them.
> 
> Reported-by: Baruch Siach <baruch at tkos.co.il>
> Signed-off-by: Alexander Graf <agraf at suse.de>
> Reviewed-by: Stephen Warren <swarren at nvidia.com>
> Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>

Thanks, applied to efi-next

Alex