Linus Torvalds wrote: > On Fri, 26 Mar 2010, Scott Lurndal wrote: > > > > I wonder if Intel's EM64 stuff makes this more deterministic, perhaps > > David's implementation would work for x86_64 only? > > Limiting it to x86-64 would certainly remove all the worries about all the > historical x86 clones. > > I'd still worry about it for future Intel chips, though. I absolutely > _detest_ relying on undocumented features - it pretty much always ends up > biting you eventually. And conditional writeback is actually pretty nasty > from a microarchitectural standpoint. On the same subject of relying on undocumented features: /* If SMP and !X86_PPRO_FENCE. */ #define smp_rmb() barrier() I've seen documentation, links posted to lkml ages ago, which implies this is fine on 64-bit for both Intel and AMD. But it appears to be relying on undocumented behaviour on 32-bit... Are you sure it is ok? Has anyone from Intel/AMD ever confirmed it is ok? Has it been tested? Clones? -- Jamie -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
