It would also be nice to know if disabling VT-d in the BIOS resolves this issue, or if building the kernel with IOMMU support and then forcibly disabling it with 'intel_iommu=off' fixes the problem. Given that you can easily reproduce this, it would be good to know how your machine differs from dozens of others which work fine with semaphores turned on...
Oh, and the output of 'lspci -nn -vv' would be nice to see in case you've got older (or newer) chips... -- keith.packard at intel.com -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 827 bytes Desc: not available URL: <http://lists.freedesktop.org/archives/dri-devel/attachments/20111223/20dde04d/attachment.pgp>