On Tuesday, June 26, 2007 8:03:48 am Andi Kleen wrote: > On Mon, Jun 25, 2007 at 08:30:52PM -0700, Jesse Barnes wrote: > > Oh, and FYI I've seen new systems with a default mapping type of WB, with > > a few uncached holes for MMIO. That means PAT will be absolutely > > required on those systems if we want to use WC for the framebuffer or > > other memory. > > Why? As long as there are still MTRRs free you could use them for > WC even in this setup.
According to the manual, you can't use WC or WT MTRRs on top of a WB MTRR range. Only UC MTRRs can override WB MTRRs, but PAT doesn't have this restriction. Jesse - 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/
