<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO --- - [IVB CPU eDP] local flat panel stays blank, workaround: intel_iommu=igfx_off" href="https://bugs.freedesktop.org/show_bug.cgi?id=48652#c116">Comment # 116</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO --- - [IVB CPU eDP] local flat panel stays blank, workaround: intel_iommu=igfx_off" href="https://bugs.freedesktop.org/show_bug.cgi?id=48652">bug 48652</a> from <a class="email" href="mailto:imre.deak@gmail.com" title="Imre Deak <imre.deak@gmail.com>"> Imre Deak</a> <pre>(In reply to <a href="show_bug.cgi?id=48652#c115">comment #115</a>) > Yes, it works. Thanks, it narrows it down. I looked through the Intel HW IOMMU code and haven't found anything obvious that could explain this. OTOH, looking again at the dmesg with the crash (dmesg-3.10.0-rc6-00406-g73bc88c) I can't see the HW IOMMU being enabled. I'd expect "PCI-DMA: Intel(R) Virtualization Technology for Directed I/O". Instead I see SWIOTLB being enabled there. But if you are using SWIOTLB I don't understand why igfx_off makes any difference. Also the workaround in my patch should be already active for SWIOTLB, so that shouldn't make any difference either. Could you check if you had that workaround in your test kernel (1625e7e549 - "drm/i915: make compact dma scatter lists creation work with SWIOTLB backend")?</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>