Tian, Kevin 於 西元2015年07月31日 09:26 寫道:
From: Ting-Wei Lan [mailto:lant...@gmail.com]
Sent: Sunday, July 26, 2015 12:58 AM
When using Linux >= 3.19 (commit 47591df) as dom0 on some Intel Ironlake
devices, It is possible to encounter graphics issues that make screen
unreadable or crash the system. It was reported in freedesktop bugzilla:
https://bugs.freedesktop.org/show_bug.cgi?id=90037
As we still cannot find a proper fix for this problem, this patch adds
iommu=igfx option to control whether Intel graphics IOMMU is enabled on
these devices. Running Xen with iommu=no-igfx is similar to running
Linux with intel_iommu=igfx_off, which disables IOMMU for Intel Ironlake
GPU. This can be used by users to manually workaround the problem before
a fix is available for i915 driver.
Signed-off-by: Ting-Wei Lan <lant...@gmail.com>
---
Changed since v1:
* Replace igfx_off with igfx
This patch is currently only build-tested because I don't have access to
the hardware that have graphics issues this week. I will test this new
patch next week.
docs/misc/xen-command-line.markdown | 12 +++++++++++-
xen/drivers/passthrough/iommu.c | 3 +++
xen/drivers/passthrough/vtd/quirks.c | 2 +-
xen/include/xen/iommu.h | 2 +-
4 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/docs/misc/xen-command-line.markdown
b/docs/misc/xen-command-line.markdown
index 13f03ad..6262be6 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -793,7 +793,7 @@ debug hypervisor only).
> Default: `new` unless directed-EOI is supported
### iommu
-> `= List of [ <boolean> | force | required | intremap | qinval | snoop |
sharept |
dom0-passthrough | dom0-strict | amd-iommu-perdev-intremap | workaround_bios_bug
| verbose | debug ]`
+> `= List of [ <boolean> | force | required | intremap | qinval | snoop |
sharept |
dom0-passthrough | dom0-strict | amd-iommu-perdev-intremap | workaround_bios_bug
| igfx | verbose | debug ]`
> Sub-options:
@@ -867,6 +867,16 @@ debug hypervisor only).
>> ignored (normally IOMMU setup fails if any of the devices listed by a DRHD
>> entry aren't PCI discoverable).
+> `igfx` (VT-d)
+
+> Default: `true`
+
+>> Enable IOMMU for Intel Calpella/Ironlake devices. This option does not
+>> affect grahpics IOMMU on other devices. The intended usage of this option
+>> is `no-igfx`, which is silimar to Linux `intel_iommu=igfx_off` option used
+>> to workaround graphics issues. If adding `no-igfx` fixes anything, you
+>> should file a bug reporting the problem.
+
For above description let's make it general, i.e Enable IOMMU for Intel
Processor
Graphics devices. You can list Calpella/Ironlake as the example, but not the
only
target. :-)
no-igfx only works with Calpella/Ironlake because
is_igd_vt_enabled_quirk() contains this code:
if ( !IS_ILK(ioh_id) )
return 1;
The newly added variable iommu_igfx only changes the return value of
is_igd_vt_enabled_quirk() when IS_ILK(ioh_id) is true. I don't know
whether we will need no-igfx on other Intel graphics devices because I
don't many devices to test and I don't have other devices that have this
problem.
Thanks
Kevin
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