Recovering from a broken frame buffer

Someone e-mailed me with this request for help:


I changed the frame buffer of my Skylake setup in an attempt to fix the artefacts and now I am getting a KP at boot time, and I only have one drive/partition and no backup. Now what?

Ouch. You should always have a backup or secondary boot option handy, but try this; boot with -DisableIOFB (in single user mode first for example) and see if that helps. Will be slower than usual, so give it some time, but it should get you past the KP.

By the way. I have QE/CI working on a friends PC, but Metal is acting up. First Apple tried to load libMTLIGCCompilerPlugin.dylib instead of libMTLIntelCompilerPlugin.dylib (from AppleIntelSKLGraphicsMTLDriver.bundle) and now the filename error is fixed and the error is no longer there in /var/log/system.log but the Metal compiler is still broken – Apple may fix this in 10.11.3 but I haven’t even downloaded the 10.11.3 DP (next week perhaps) so we’ll have to wait and see what is next.

Oh and you may also want to play with the following preferences:

defaults read/write MTLIRDumpEnable [0/1]
defaults read/write MTLIGILInjectionEnable [0/1]
defaults read/write MTLCB2CREnable [0/1]

Check /tmp/MTLIntelCompilerDumps/ for output!

One of the settings may work with ‘DumpMetal’ and/or ‘ShaderDumpEnabled’.

Hope that this helps. Have to get back to my family now…

2 thoughts on “Recovering from a broken frame buffer

  1. Do you have QE/CI working without artifacts?
    I added the preferences but there was no output in /tmp/MTLIntelCompilerDumps/. I also removed Metal completly but the artifacts are still there (10.10.3 DP).

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