Re: kernel unaligned accesses on IA64 in IDE

[Borislav Petkov <petkovbb@googlemail.com>]

On Fri, Aug 22, 2008 at 02:38:12PM -0700, Nishanth Aravamudan wrote:
> On 22.08.2008 [22:54:31 +0200], Borislav Petkov wrote:
> > On Fri, Aug 22, 2008 at 01:36:06PM -0700, Luck, Tony wrote:
> > > > How about long instead of int.  int leaves us with the possibility that
> > > > something else will expect 8 byte alignment.
> > > 
> > > How about this?
> > > 
> > > Align __cmd to ward off kernel unaligned access consoles messages on
> > > ia64 (and perhaps make an almost imperceptible performance improvement
> > > on other architectures that can handle unaligned access, but do so
> > > more slowly than aligned accesses).
> > 
> > By the way, i've been wondering, this unaligned access breaking should have
> > happened earlier, how did we miss that? Nish, Robin, can you see that in some
> > older logs?
> 
> I replied about this in a separate sub-thread, but you may not have been
> on the direct Cc (though linux-ide should have been).
> 
> This all began because I noticed one of my automated test machines had
> not successfully booted a kernel in some time. I investigated via
> bisection and found that CONFIG_PRINTK_TIME=y was broken on my IA64 box.
> With Tony and Peter Z's help, that bug was resolved, but then with the
> console working, I noticed these unaligned accesses. Sorry if it seemed
> like, from my posting, they were a regression, I did not mean to give
> that impression.
> 
> They may have been there for some time, but I don't have any logs from
> kernels before 2.6.27-rc3, because of the CONFIG_PRINTK_TIME=y breakage
> (which was being set by default for this box). I could go back and try
> older kernels, if you'd like, but it would take some time.

Thanks for clarifying but it's not needed anymore since we know about the
problem now. I was simply wondering why similar reports didn't appear earlier
since the code that causes it is not that new - I guess there aren't that many
ia64 machines using ide-cd from a recent kernel out there :)

-- 
Regards/Gruss,
    Boris.