On Wed, Jan 06, 2016 at 01:52:17PM +0200, Michael S. Tsirkin wrote: > > > Peter, what do you think? How about I leave this patch as is for now? > > > > No, and I object to removing the single byte implementation too. Either > > remove the full arch or fix xchg() to conform. xchg() should work on all > > native word sizes, for SH that would be 1,2 and 4 bytes. > > Rick, maybe you could explain how is current 1 byte xchg on llsc wrong?
It doesn't seem to preserve the 3 other bytes in the word. > It does use 4 byte accesses but IIUC that is all that exists on > this architecture. Right, that's not a problem, look at arch/alpha/include/asm/xchg.h for example. A store to another portion of the word should make the store-conditional fail and we'll retry the loop. The short versions should however preserve the other bytes in the word. SH's cmpxchg() is equally incomplete and does not provide 1 and 2 byte versions. In any case, I'm all for rm -rf arch/sh/, one less arch to worry about is always good, but ISTR some people wanting to resurrect SH: http://old.lwn.net/Articles/647636/ Rob, Jeff, Sato-san, might I suggest you send a MAINTAINERS patch and take up an active interest in SH lest someone 'accidentally' nukes it? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/