* Andreas Herrmann3 <[EMAIL PROTECTED]> wrote: > On Thu, Jan 17, 2008 at 10:42:09PM +0100, Ingo Molnar wrote: > > > > * Siddha, Suresh B <[EMAIL PROTECTED]> wrote: > > > > > On Thu, Jan 17, 2008 at 10:13:08PM +0100, Ingo Molnar wrote: > > > > but in general we must be robust enough in this case and just degrade > > > > any overlapping page to UC (and emit a warning perhaps) - instead of > > > > failing the ioremap and thus failing the driver (and the bootup). > > > > > > But then, this will cause an attribute conflicit. Old one was > > > specifying WB in PAT (ioremap with noflags) and the new ioremap > > > specifies UC. > > > > we could fix up all aliases of that page as well and degrade them to UC? > > Yes, we must fix all aliases or reject the conflicting mapping. But > fixing all aliases might not be that easy. (I've just seen a panic > when using your patch ;-(
yes, indeed my patch is bad if you have PAT enabled: conflicting cache attributes might be present. I'll go with your patch for now. should we perhaps do UC by default for early_ioremap() as well? Normally those mappings are only temporary - but in case of a leak they might hang around in the pagetables and the CPU might stumble upon them. Also, should early_iounmap() do a wbinvd() [/clflush()] call as well, to be safe? Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/