path: root/Software/Beignet.mdwn
diff options
authorRebecca N. Palmer <>2015-05-16 18:52:59 +0100
committerZhigang Gong <>2015-05-18 02:12:01 -0700
commit00f749ed9a5b7a900328041ccdcbb36bb83500d5 (patch)
treea009d166a308d045f25b935f106a19f9eabf68a7 /Software/Beignet.mdwn
parentef0794d3e5548b412ce22e44c6484c1272e516a0 (diff)
Docs: update/clarify Haswell issues
Reflect recent beignet and Linux changes.
Diffstat (limited to 'Software/Beignet.mdwn')
1 files changed, 26 insertions, 14 deletions
diff --git a/Software/Beignet.mdwn b/Software/Beignet.mdwn
index 8504c8f6..710fc982 100644
--- a/Software/Beignet.mdwn
+++ b/Software/Beignet.mdwn
@@ -140,7 +140,7 @@ Supported Targets
* 3rd Generation Intel Core Processors
* Intel “Bay Trail” platforms with Intel HD Graphics
- * 4th Generation Intel Core Processors, need kernel patch currently, see the "Known Issues" section.
+ * 4th Generation Intel Core Processors "Haswell", need kernel patch currently, see the "Known Issues" section.
* 5th Generation Intel Core Processors "Broadwell".
Known Issues
@@ -161,22 +161,34 @@ Known Issues
But this command is a little bit dangerous, as if your kernel really hang, then the gpu will lock up
forever until a reboot.
-* Almost all unit tests fail.
- There is a known issue in some versions of linux kernel which enable register whitelist feature
- but miss some necessary registers which are required for beignet. For non-HSW platforms, the
- problematic version are around 3.15 and 3.16 which have commit f0a346b... but haven't commit
- c9224f... If it is the case, you can apply c9224f... manually and rebuild the kernel or just
- disable the parse command by invoke the following command (use Ubuntu as an example):
+* "Beignet: self-test failed" and almost all unit tests fail.
+ Linux 3.15 and 3.16 (commits [f0a346b](
+ to [c9224fa](
+ enable the register whitelist by default but miss some registers needed
+ for Beignet.
+ This can be fixed by upgrading Linux, or by disabling the whitelist:
`# echo 0 > /sys/module/i915/parameters/enable_cmd_parser`
- For HSW platforms, this issue exists in all linux kernel version after 3.15. We always need
- to execute the above command.
-* Some unit test cases, maybe 20 to 30, fail on 4th Generation (HSW) platform.
- _The 4th Generation Intel Core Processors's support requires some Linux kernel
- modification_. You need to apply the patch at:
- [](
+ On Haswell hardware, Beignet 1.0.1 to 1.0.3 also required the
+ above workaround on later Linux versions, but this _should not_ be
+ required in current (after [83f8739](
+ git master.
+* "Beignet: self-test failed" and 15-30 unit tests fail on 4th Generation (Haswell) hardware.
+ On Haswell, shared local memory (\_\_local) does not work at all on
+ Linux <= 4.0, and requires the i915.enable_ppgtt=2 [boot parameter](
+ on Linux 4.1.
+ This will be fixed in Linux 4.2; older versions can be fixed with
+ [this patch](
+ If you do not need \_\_local, you can override the self-test with
+ but using \_\_local after this may silently give wrong results.
* Precision issue.
Currently Gen does not provide native support of high precision math functions