On Tue, 27 Nov 2007 09:16:07 -0800 "H. Peter Anvin" <hpa@xxxxxxxxx> wrote: > Stephen Hemminger wrote: > > Herbert Xu wrote: > >> On Sat, Nov 24, 2007 at 02:49:36PM +0100, Johannes Berg wrote: > >> > >>> Right. I just didn't think that would be a valid value for an > >>> architecture to set. > >>> > >> > >> OK. Let me clarify this a bit more. We require at least one > >> of the following rules to be met: > >> > >> * the IPv4/IPv6 header is aligned by 8 bytes on reception; > >> * or the platform provides unaligned exception handlers. > >> > >> So if your platform violates both rules then it won't work with > >> the IP stack, simple as that. Fortunately I don't think such a > >> platform exists currently on Linux. > >> > >> Cheers, > >> > > > > Then what about hardware that can't dma ethernet to non-aligned address. > > Sky2 hardware breaks if DMA is not 8 byte aligned. IMHO the IP stack > > should handle any alignment, and do the appropriate memove if the CPU requires > > alignment. > > I wrote a patch for the IP stack to realign packets if necessary at one > point. I should dredge it up again and submit it for collective flamage. > > -hpa > Is there any standard kernel config define for "this platform can't do unaligned accesses"? -- Stephen Hemminger <shemminger@xxxxxxxxxxxxxxxxxxxx> - To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
