Re: [PATCH] b43: Fix possible unaligned u32 access

["John W. Linville" <linville@tuxdriver.com>]

On Fri, Jun 05, 2009 at 05:03:57PM +0200, castet.matthieu@free.fr wrote:
> Quoting "John W. Linville" <linville@tuxdriver.com>:
> 
> > On Thu, Jun 04, 2009 at 11:18:33PM +0200, Michael Buesch wrote:
> > > From: Matthieu CASTET <castet.matthieu@free.fr>
> > >
> > > Fix possible unaligned u32 access in b43_generate_plcp_hdr().
> > > Unaligned data is read/write with a u32 pointer instead of using the
> > > packed structure. Some versions of gcc ignore the "packed" attribute, if
> > the
> > > structure element is accessed through a local pointer.
> > >
> > > Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
> > > Signed-off-by: Michael Buesch <mb@bu3sch.de>
> >
> > That seems pretty brain-dead...can you cite a source for this
> > information?
> The test I did with the attached test case in the first post.

Link?

> I don't see why gcc should propagate packed structure info to assignment.
> That will be impossible to handle (think of passing it to function parameter).

Perhaps this is obvious to you, but it isn't to me.

> 
> > The patch seems like a no-op...
> At least the code produced on mips is different.

Then why aren't you trying to get the mips gcc guys to fix it?

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.