Bug 101381

Summary: [i915] can't set i1915.semaphores=1 on kernel 4.9 and above
Product: DRI Reporter: nunesgabrielbr
Component: DRM/IntelAssignee: Intel GFX Bugs mailing list <intel-gfx-bugs>
Status: CLOSED NOTABUG QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: normal    
Priority: medium CC: intel-gfx-bugs
Version: unspecified   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
Dmesg output none

Description nunesgabrielbr 2017-06-11 18:48:48 UTC 
Created attachment 131880 [details]
Dmesg output

Hi.

Ever since I upgraded to kernels >4.9, I'm unable to set the i915.semaphores option enabled (=1). Already tried Ubuntu, Debian, Arch and openSUSE and tried setting the option both on /etc/default/grub and /etc/modprobe.d/i915.conf. With kernels prior to 4.9, everything was working fine.

uname -rm:
4.11.4 x86_64

cat /proc/cmdline:
BOOT_IMAGE=/boot/vmlinuz-4.11.4 root=UUID=16e0a6c5-d60a-483e-a949-0b58aaf42417 ro rhgb quiet i915.semaphores=1

cat /sys/module/i915/parameters/semaphores:
0

Distro:
Fedora 25 Workstation

Video adapter:
Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)

Dmesg attached.
Comment 1 Elizabeth 2017-06-13 20:43:23 UTC 
Hello Gabriel, could you please add the parameter "drm.debug=0xe" in the grub and then get the dmesg again. Also, if possible, could you add the hardware information and a dmesg log with the old kernel where the i915.semaphores is working with the same drm.debug=0xe parameter added. Thanks.
Comment 2 Chris Wilson 2017-06-14 07:17:58 UTC 
You can't enable semaphores as that hw does not support semaphores, that is what the kernel is telling you.

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