Am Freitag, 24. November 2006 06:00 schrieb Nikita V. Youshchenko:
> > However, I've located one more problem which I don't know yet how to fix
> > correctly.
> > AFAIR, device may pass several incoming frames in one urb, and second
> > and later frames are 2-byte-aligned.
> > This may cause situations when IP layer gets IP packet not aligned at
> > 32-bit word boundary and occasionally crash because of unligned access
> > (hardware and/or codebase I'm working with really dislikes unaligned
> > accesses from kernel).
> >
> > Looks the only way to fix that is to detect such cases, and copy data?
> > But this will hurt performance on systems that can handle unaligned
> > accesses ...
>
> One more attempt, with typo fixed ...
>
> Attached is a patch that handles this, based on additional Kconfig key.
> I've tested this on hardware and kernel I'm working with, and then
> forward-ported to 2.6.19-pre6
Don't introduce a config option. If you do this by ifdef, use ifdef on the
arches that you used as default. On those arches the memmove is definitely
a win.
You could even test it unconditionally on i386 or x86_64. A copy may be
faster than keeping it in place, as you touch the data many times, but
copy it only once.
Regards
Oliver
-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys - and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
_______________________________________________
linux-usb-devel@lists.sourceforge.net
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
