[Bug 94605] [SKL] Flashing black screen ([drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=94605

--- Comment #85 from syphyr at gmail.com ---
(In reply to Mauro Santos from comment #84)
> (In reply to syphyr from comment #83)
> > Could you try replacing "intel_iommu=on" with:
> > intel_iommu=igfx_off
> > 
> > I also still have problems with intel_iommu=on.
> 
> I have been trying something alonf those lines, so far I've given a good
> afternoon with intel_iommu=on,igfx_off and I didn't see any problems, now
> I'm testing without intel_iommu in the cmdline and I expect to see no
> problems.
> 
> If the problem is not solved it is much harder to trigger now, however
> partially disabling the iommu kind of defeats one of the main points of
> using it, restricting devices form having full unchecked access to the whole
> ram.
> 
> On another note, if I'm not wrong, using intel_iommu=igfx_off is the same as
> having the iommu completely off so you may want to check dmesg and make sure
> if the iommu is on or not.

Using intel_iommu=igfx_off is not the same as completely having the intel iommu
off.  I am still seeing this using "igfx_off":

[    0.076183] DMAR: Host address width 39
[    0.076184] DMAR: DRHD base: 0x000000fed90000 flags: 0x0
[    0.076188] DMAR: dmar0: reg_base_addr fed90000 ver 1:0 cap 1c0000c40660462
ecap 7e3ff0505e
[    0.076189] DMAR: DRHD base: 0x000000fed91000 flags: 0x1
[    0.076193] DMAR: dmar1: reg_base_addr fed91000 ver 1:0 cap d2008c40660462
ecap f050da
[    0.076194] DMAR: RMRR base: 0x0000008aca9000 end: 0x0000008acc8fff
[    0.076194] DMAR: RMRR base: 0x0000008b800000 end: 0x0000008fffffff
[    0.076196] DMAR-IR: IOAPIC id 2 under DRHD base  0xfed91000 IOMMU 1
[    0.076197] DMAR-IR: HPET id 0 under DRHD base 0xfed91000
[    0.076198] DMAR-IR: x2apic is disabled because BIOS sets x2apic opt out
bit.
[    0.076198] DMAR-IR: Use 'intremap=no_x2apic_optout' to override the BIOS
setting.
[    0.077630] DMAR-IR: Enabled IRQ remapping in xapic mode

-- 
You are receiving this mail because:
You are on the CC list for the bug.
You are the assignee for the bug.
You are the QA Contact for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20161105/12773245/attachment-0001.html>