[U-Boot] [PATCH] disk: add -mno-unaligned-access to CFLAGS

[Marc Dietrich]

Albert,

On Friday 29 March 2013 08:00:54 Albert ARIBAUD wrote:
> On Thu, 28 Mar 2013 23:35 +0100, Marc Dietrich <marvin24 at gmx.de> wrote:
> > [ ... ]
> > On Thursday 28 March 2013 21:42:13 Albert ARIBAUD wrote:
> > > 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.
> 
> Thanks for clarifying.
> 
> Considering this is about a very small number of reads, I strongly
> prefer that these reads be done through the get_unaligned(&field) macro
> defined in e.g. arch/arm/include/asm/unaligned.h, even at the slightly
> added cost of decomposing the reads into 8-bit accesses.

ok, this is what I was actually looking for :-) I've sent a new patch.

Marc