[PATCH V2] purgatory: Change default sha256 optimization to -O2

[Simon Horman]

On Thu, Dec 01, 2016 at 11:09:37AM -0800, Geoff Levand wrote:
> Change the default purgatory sha256 code optimization from -O0 to -O2, and add a
> new arch specific makefile variable $(ARCH)_PURGATORY_SHA256_CFLAGS which can
> over ride this default.  Set ia64_PURGATORY_SHA256_CFLAGS to -O0 to retain the
> previous optimization level for ia64.
> 
> The purgatory sha256 code needs the be built with -O0 for the  ia64
> architecture.  Currently this code is built with -O0 for all architectures,
> which slows down the calculations for architectures which could otherwise
> use -O2.
> 
> On arm64, it takes around 20 second to verify SHA in purgatory when
> vmlinuz image is around 13MB and initramfs is around 30M with -O2
> enabled. Otherwise, it takes more than 2 minutes.
> 
> Cc: Pratyush Anand <panand at redhat.com>
> Signed-off-by: Geoff Levand <geoff at infradead.org>

Thanks, applied.