Ralf Baechle wrote:
>
> On Tue, Jul 31, 2001 at 09:12:22PM +0400, kuznet@xxxxxxxxxxxxx wrote:
>
> > > copy the packet to a fresh skb (rx_copybreak = 0), the packet will
> > > traverse the net layer with unalinged IP header.
> >
> > Doing this for an arch which traps wrong alignment, you can expect
> > everything (except for crash, which could be bug).
>
> Afaik all such architectures have exception handlers to complete the access
> transparently in software. Such an access is very slow so where more
> frequent unaligned accesses are expected there are get_unaligned() and
> put_unaligned().
I was recently asked to remove the get/put_unaligned code from my
VLAN patch, which I did. However, I don't want to now pay a
performance penalty on Sparc, or whatever...
So, what are the drawbacks of using get/put_unaligned? If it's a
Macro, it could be defined to do very little extra work on architectures
that can handle un-aligned access, which might fix the common case, and
yet still be faster than catching the trap on other hardware architectures??
Thanks,
Ben
>
> Ralf
--
Ben Greear <greearb@xxxxxxxxxxxxxxx> <Ben_Greear@xxxxxxxxxx>
President of Candela Technologies Inc http://www.candelatech.com
ScryMUD: http://scry.wanfear.com http://scry.wanfear.com/~greear
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