[U-Boot] [PATCH 01/10] Fix IP alignement problem

[Ben Warren]

Hi Olav,

On Fri, Oct 10, 2008 at 11:53 AM, Olav Morken <olavmrk at gmail.com> wrote:

> On Fri, Oct 10, 2008 at 7:01 PM, Ben Warren <biggerbadderben at gmail.com>
> wrote:
> > Olav Morken wrote:
> >>
> >> This patch removes volatile from:
> >> volatile IP_t *ip = (IP_t *)xip;
> >>
> >> Due to a bug, avr32-gcc will assume that ip is aligned on a word
> boundary
> >> when
> >> using volatile, which causes an exception since xip isn't aligned on a
> >> word
> >> boundary.
> >>
> >
> > What other architectures have you tried this on?
>
> None, as we don't have any other boards to test on. I do however believe
> that this change should have no side-effects. If any architectures
> relied on this function working as some sort of memory/io barrier, they
> would have problems with other functions such as ArpRequest, which
> doesn't have anything that will work as a memory/io barrier before the
> eth_send function.
>
> Of course, I could be wrong. I would certainly not suggest including
> this change without some more testing.
>
> The bug which causes this problem is in avr32-gcc, which makes
> assumptions about the alignement of IP_t when using volatile, and this
> change shouldn't be necessary once that bug is fixed. Until that bug
> is fixed, this change is needed for anyone trying to run U-Boot on
> this microcontroller.
>

I don't mean to be a pain, it's just that this code is shared by everything,
so we need to be really careful.  I agree with Haavard that the volatile
keyword is probably used much more than it should be in the networking
library.

I'll pull this into the net/testing branch in the next couple of days, and
hopefully we'll get some volunteers to try it out on different
architectures.

regards,
Ben