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Video locked up completely. Mouse wouldn't move, CTL-ALT-F1 wouldn't switch to emergency backup console. Logged in via putty; from that login, the system seemed to be running normally, but nothing would unwedge the display, including unity --replace

I gave up and rebooted, but the reboot process never changed the display; I had to power cycle the system.

dmsg -T printed messages like this one; they were in syslog after the power cycle.

May 13 13:18:20 desktop kernel: [185318.986092] nouveau 0000:01:00.0: fifo: CACHE_ERROR - ch 9 [firefox[24095]] subc 5 mthd 0180 data beef0301

(All things being equal, I'd just as soon use the open source software, but I just switched to the Nvidia proprietary drivers per the instructions here: Install Nvidia driver instead nouveau)

Community
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Mike
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2 Answers2

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I encountered a similar error on fedora 25 - sometimes with chrome, and much more frequently with the webkit based native/default web browser.

The video display, mouse, keyboard would all freeze, but the ssh login would work - allowing one to see the nouveau cache errors in dmesg.

I tried a few arguments from https://nouveau.freedesktop.org/wiki/KernelModuleParameters/ , and developed the following workaround:

Add nouveau.nofbaccel=1 to the Linux kernel line during booting. On fedora it can be done by making changes to /etc/default/grub so that a line similar to this exists: GRUB_CMDLINE_LINUX="verbose nouveau.nofbaccel=1"

After this, install this command line using grub mkconfig:

grub2-mkconfig -o /boot/grub2/grub.cfg

Reboot - preferably manually inspect that the command line has the flag.

After this change, the performance is a bit worse - but hardware acceleration is still detected by desktop manager - hence it works in full graphics mode.

Can you try this command line flag on Ubuntu boot on the line which specifies the Linux kernel to load.

George Udosen
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vpathak
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I've tried nouveau.nofbaccel=1 for serveral weeks with no improvement but found the variation below has been stable for 24 hours!

Your millage may vary :-)

nouveau.noaccel=1

John Lyons
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