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@tkos.co.il Signed-off-by: Alexander Graf agraf@suse.de Reviewed-by: Stephen Warren swarren@nvidia.com Reviewed-by: Heinrich Schuchardt xypron.glpk@gmx.de
Thanks, applied to efi-next
Alex