VMware graphics driver issue

Current Linux kernel master does not boot on VMware 7.1.2. The bad commit is apparently dabdcdc9822ae4e23cd7ff07090098d34f287b28, “drm/vmwgfx: Switch to mode_cmd2”. Unsurprisingly, it seems to affect VMware graphics (vmwgfx). Now, trying to figure out a fix.

Trying to figure out a fix

Figuring out a fix for this problem is relatively important for me, in so far as I suspect I will soon want to be able to test things like kvm patches, and I probably want to do that against the “in progress” kernel.

Getting help

I sent a mail to the people listed in the patch asking for help about the problem. Frankly, I have no clue how the VMware graphics driver in Linux works (I get the general idea, I have no idea about the details).

Reverting the patch

I tried to revert the patch to see if that helps. The patch reverts cleanly on the current master, which is good news. But it does not really fix the problem, apparently.

Bad bisect?

Reverted to the previous commit, and it still does not boot:

[    2.564588] usb 2-2.1: SerialNumber: 000650268328
[    3.064904] clocksource: Switched to clocksource tsc
[  OK  ] Started Show Plymouth Boot Screen.
[  OK  ] Reached target Paths.
[  OK  ] Started Forward Password Requests to Plymouth Directory Watch.
[  OK  ] Reached target Basic System.
G[   59.019523] random: crng init done

So there is an issue with how I did the bisect, apparently.

Testing again, three of the versions that were marked “Good” in my logs now stopped working (ad1231080be5a5cb, bfd5be0f9e0cd and 8e57ec613). While I believe it’s easy to make one mistake or even two, I doubt I did three mistakes evaluating “boots” or “does not boot” in a row. So this may not be a black and white bug, but more like a slightly Heisenbugguestque problem that will require a little more care.

There something about keyboards

I like it when I type something and the computer knows what I typed. Even under moderate load, I noticed that I sometimes get repeated keys. For example, I just hit the Alt key in Gnome to select System Monitor, while a git checkout was in progress. I typed “system”, and got “sysssstem” instead. Seriously?

That puts into some perspective comments I received that it was lousy Apple hardware and bad keyboards 😉

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Author: Christophe de Dinechin

I try to change the world, but that's work in progress. If you want to know me, google "Christophe de Dinechin". Keywords: concept programming, virtualization, OS design, programming languages, video games, 3D, modern physics. Some stuff I did that I'm proud of: the first "true" 3D game for the PC, HP's big iron virtualization, real-time test systems for car electronics, some of the best games for the HP48 calculator, a theory of physics that makes sense (at least to me).

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