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ARM: Remove -mno-unaligned-access 

We've decided that it is generally okay for coreboot to expect unaligned
accesses to work. Trying to find all instances of unaligned access
opportunities and working around them in software would be an
unsustainable whack-a-mole contest. Instead, architectures and boards
need to make sure they conform to this, which on ARM and ARM64 requires
setting up paging early in the bootblock.

Other architectures (x86, ARM64, MIPS) already generate code in this
manner. ARM still had an -mno-unaligned-access flag hanging around that
has been copied so many times its initial origin was lost in time
(probably U-Boot). Let's remove it for consistency between architectures
and to improve code generation.

BRANCH=veyron
BUG=None
TEST=Booted Jerry and Blaze. Looked at the disassembly for
timestamp_sync() and confirmed that it only gives you half as much eye
cancer as before (GCC still somehow insists on byte accesses when
zeroing fields which is very odd, but at least that terrible AND/OR mess
is gone). Measured a boot time increase of about 11ms on Jerry (mostly
faster timestamp and CBFS accesses). Could not test Storm because
despite our claimed abundance of test devices, every time I get one of
them it magically disappears again in less than a week.

Change-Id: I8fc08cc7ce4471651a51ee795269909ef69277c8
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 07591fadb89bd127fe065abf0b9ba3facecf1aeb
Original-Change-Id: I1d046e05bb11822b86e467eafb6aa92e8fbce774
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/241732
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9728
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <edward.ocallaghan@koparo.com>
This commit is contained in:
Julius Werner 2015-01-16 16:06:00 -08:00 committed by Patrick Georgi
parent 6addd40268
commit 1968b58010
1 changed files with 1 additions and 1 deletions
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toolchain.inc
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@ -60,7 +60,7 @@ ARCHDIR-arm64 := arm64
ARCHDIR-riscv := riscv ARCHDIR-riscv := riscv
ARCHDIR-mips := mips ARCHDIR-mips := mips
CFLAGS_arm := -mno-unaligned-access -ffunction-sections -fdata-sections CFLAGS_arm := -ffunction-sections -fdata-sections
CFLAGS_arm64 := -ffunction-sections -fdata-sections CFLAGS_arm64 := -ffunction-sections -fdata-sections