[PATCH 06/10] arm64/efi: use UEFI memory map unconditionally if available

[Mark Salter]

On Wed, 2014-10-22 at 19:20 +0200, Ard Biesheuvel wrote:
> On 22 October 2014 19:06, Mark Salter <msalter at redhat.com> wrote:
> > On Wed, 2014-10-22 at 16:21 +0200, Ard Biesheuvel wrote:
> >> On systems that boot via UEFI, all memory nodes are deleted from the
> >> device tree, and instead, the size and location of system RAM is derived
> >> from the UEFI memory map. This is handled by reserve_regions, which not only
> >> reserves parts of memory that UEFI declares as reserved, but also installs
> >> the memblocks that cover the remaining usable memory.
> >>
> >> Currently, reserve_regions() is only called if uefi_init() succeeds.
> >> However, it does not actually depend on anything that uefi_init() does,
> >> and not calling reserve_regions() results in a broken boot, so it is
> >> better to just call it unconditionally.
> >>
> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> >> ---
> >>  arch/arm64/kernel/efi.c | 11 ++++-------
> >>  1 file changed, 4 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
> >> index 51522ab0c6da..4cec21b1ecdd 100644
> >> --- a/arch/arm64/kernel/efi.c
> >> +++ b/arch/arm64/kernel/efi.c
> >> @@ -313,8 +313,7 @@ void __init efi_init(void)
> >>       memmap.desc_size = params.desc_size;
> >>       memmap.desc_version = params.desc_ver;
> >>
> >> -     if (uefi_init() < 0)
> >> -             return;
> >> +     WARN_ON(uefi_init() < 0);
> >>
> >>       reserve_regions();
> >>  }
> >
> > It also looks like EFI_BOOT flag will be set even if uefi_init fails.
> > If uefi_init fails, we only need reserve_regions() for the purpose
> > of adding memblocks. Otherwise, we end up wasting a lot of memory.
> 
> Indeed. But perhaps it would be cleaner to add the memblocks in a
> separate function that gets called before uefi_init(), let
> reserve_regions() do just what it name implies, and retain the above
> hunk so that the reserve_regions() call is only performed if UEFI
> initialized correctly.
> 

That works for me.