On Tue, Jan 13, 2009 at 10:21:52PM +0100, Gerd Hoffmann wrote: > Dave Jones wrote: > > On Tue, Jan 13, 2009 at 09:55:27PM +0100, Gerd Hoffmann wrote: > > > Bill Nottingham wrote: > > > > Here's some proposed config changes. > > > > > > Jumping on the wagon ;) > > > > > > Can we enable CONFIG_DMAR please? This turns on the IOMMU on intel > > > boxes, using VT-d. Called "DMA Remapping" in intel speak, this is where > > > the config option name comes from. Advantages: > > > > > > (1) 32bit PCI devices can DMA to memory above 4G, thus the need for > > > swiotlb (i.e. bounce buffers) is gone. > > > (2) It allows kvm to pass through PCI devices to guests securely. > > > > The last time we tried this, it blew up a lot due to broken BIOSes. > > Do you have bug numbers at hand? > Searching for CONFIG_DMAR gives me "Zarro Boogs found". > > > Maybe it's been improved enough to tolerate them, so we can probably > > give it a spin in rawhide for a while to see what happens. > > Well, it works for me. Single test box only though. As the machine in > question actually has memory above 4G it is a nice speedup for kernel > builds (sys time going down from ~15min to ~5min). > I've just enabled it (and GFX_WA and FLOPPY_WA on x86_64.) (I'm suprised it's x86_64 only, surely virtualization enabled i386 could benefit from DMA protection?) _______________________________________________ Fedora-kernel-list mailing list Fedora-kernel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-kernel-list
