[PATCH v2] libertas: Fix alignment issues in libertas core

[Erwin Authried]

Am Mittwoch, den 28.01.2009, 07:49 -0800 schrieb Andrey Yurovsky:
> On Wed, Jan 28, 2009 at 12:34 AM, Erwin Authried <eauth at softsys.co.at> wrote:
> > is it really necessary to pack all structures in hostcmd.h? The "packed"
> > attribute makes the code larger and slower. I have changed the order in
> > the lbs_private structure in dev.h a little bit so that resp_buf is on a
> > 32-bit boundary. Then, I have removed most of the packed attributes in
> > hostcmd.h (where all 16 or 32-bit Variables are on 16/32 bit boundaries
> > anyway). The libertas module is a bit smaller, and I haven't seen any
> > problem.
> 
> Thanks Erwin.  What CPU or CPUs have you tested your changes on?  In
> our case, the Blackfin (and, reportedly, the AVR32) needed us to
> guarantee alignment whereas ARM and x86 worked fine as things were
> before.  Also although it's less efficient, we can now add commands
> more safely if we use the packed attribute consistently rather than
> counting bytes, and there's a good chance that more host command
> structures will be added in the near future.

I have tested with ARM7TDMI (AT91FR40162), there is no aligment trap.
The cpu simply ignores the lowest address bits and produces wrong
assignments when the alignment isn't correct.

-Erwin

> 
> > Am Montag, den 12.01.2009, 13:14 -0800 schrieb Andrey Yurovsky:
> >> Data structures that come over the wire from the WLAN firmware must be packed.
> >> This fixes alignment problems on the blackfin architecture and, reportedly, on
> >> the AVR32.
> >>
> >> This is a replacement for the previous version of this patch which had also
> >> explicitly used get_unaligned_ macros.  As Johannes Berg pointed out, these
> >> macros were unnecessary.
> >>
-- 
Dipl.-Ing. Erwin Authried
Softwareentwicklung und Systemdesign