Hi Albert,
On Thursday 28 March 2013 21:42:13 Albert ARIBAUD wrote:
On Thu, 28 Mar 2013 19:57:31 +0100, Marc Dietrich marvin24@gmx.de wrote:
Many on-disk structures used in the directory are accessed in a non aligned manner. gcc => 4.7 (and gcc-4.6 from Linaro) switched to -munaligned-access on default causing exceptions on ARM. The easiest way to fix this is to force no-unaligned-access in this (non speed critical) directory.
Signed-off-by: Marc Dietrich marvin24@gmx.de
disk/Makefile | 1 + 1 file changed, 1 insertion(+)
diff --git a/disk/Makefile b/disk/Makefile index 5affe34..01134a3 100644 --- a/disk/Makefile +++ b/disk/Makefile @@ -24,6 +24,7 @@
include $(TOPDIR)/config.mk
#CFLAGS += -DET_DEBUG -DDEBUG
+CFLAGS += -mno-unaligned-access
LIB = $(obj)libdisk.o
Which fields, which structures, which files are affected by the unalignment issue?
in my test case, it is the start sector of a partition (check include/part_efi.h). disk/part_efi.c reads the legacy mbr (to an aligned buffer) which has a partition structure on offset 440+4+2 (<- not aligned to 4 byte boundary) and inside this a 32 bit field start_sect (aligned to 4 byte boundary). Reading this field (and also the next, nr_sects) will cause an exception. Same is for part_dos, but there we still use le32_to_int which reads byte by byte. I didn't checked others.
Marc