/srv/irclogs.ubuntu.com/2018/05/31/#ubuntu-kernel.txt

=== himcesjf_ is now known as him-cesjf
xandeyHi Kernel Team, I'm trying to bisect a bug which is in ubuntu releases, but doesn't show up in mainline builds. Is there some way to get the git history back to a mainline build? I can't seem to find this history in ubuntu-bionic.git12:35
cascardoxandey: you can use the 4.15 tag, and the Ubuntu-4.15.0-* tags12:38
xandeycassardo: ah, i was looking for v4.15.17. Also, I wasn't able to build commits which have labels like "UBUNTU: Ubuntu-4.15.0-4.5" but aren't actually tagged... is it possible this is some sort of rebase or toolchain change?12:46
xandeycassardo: some of them ask me to change config options when following https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel12:47
cascardoxandey: yes, very likely a rebase13:15
cascardoduring development, those kernels are based on rc releases13:15
cascardofurther down the stable pipeline, you will more likely see kernels all based on v4.1513:16
cascardoand fast-forward, all of those reachable from the master branch, at least after the GA kernel13:16
cascardobut as we are so close to GA, the oldest one you will find is Ubuntu-4.15.0-9.1013:17
xandeycaascardo: right, I confirmed that I get the issue with 4.15.0-9.10 (building myself and downloading prebuilt from launchpad). However, I don't see the issue in any of the mainline built kernels 4.15.0-rc1, 4.15.17, 4.17.0-rc6.13:27
xandeycascardo: I guess i'm looking to see if there's any more narrowing I can do at this point. But perhaps this is as good as I can do here, and it's time to try and debug directly.13:30
cascardowhat's the issue? did you report a bug already?13:34
xandeyyeah: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/176813913:34
ubot5Ubuntu bug 1768139 in linux (Ubuntu) "Kernel crash when booting laptop with hdmi monitor connected" [Low,Triaged]13:34
xandeyit's a kernel crash when a dell laptop is connected to hdmi and boots up, but only with ubuntu kernel13:35
xandeyi was trying to do the rebase for the bug report13:35
xandeysorry, *bisect*13:35
xandeyalthough I didn't see that last comment yet13:36
cascardoxandey: you don't happen to have a Thinkpad X1, do you?13:52
xandeynope, dell insprion 1513:57
xandeycascardo: Dell Inspiron 755913:58
cascardook, i915 change in 4.15.0-9 was related to X1 only14:17
xandeywell, it's not that I narrowed it down to 4.15.0-9, it's only that that's as far back as I was able to build.14:40
xandeyOh, looking back at my notes, it looks like I also managed to test 4.15.0-1_4.15.0-1.2 which asked me to change some cofig options, but also displayed the issue.14:42
xandeyI could try reverting dc0f16f9b5084e6be2b8c79f8c6cd499a3451791 which appears to be the only change between 4.15 and  4.15.0-1_4.15.0-1.2 in drivers/gpu/drm/i91514:45
xandeybut I don't see that as a difference between the 4.15.17 from linux-stable and 4.15.0-24 14:47
xandeyanyway, I don't mean to take up your time with a low priority bug, I just thought perhaps I was missing something with the build setup.14:50
cascardolooking at the stack trace and the diff, it's hard to think this would be specific to ubuntu kernels15:09
cascardodid you try our mainline builds?15:10
xandeyyes, I tried the ones from http://kernel.ubuntu.com/~kernel-ppa/mainline/?C=N;O=D I also built the mainline myself15:11
xandeymaybe some sort of module packaging difference?15:11
cascardowell, enabling some drm debug could help15:14
xandeycould you direct me a bit there?15:15
xandeydrm.debug=0xe on kernel command line?15:16
cascardosomething like that, let me look at the interesting bits of i915 and see which flag would trigger them15:17
cascardo=0x415:23
cascardoKMS seems to have most of it15:23
xandeyokay, i'll try that15:35
=== himcesjf_ is now known as him-cesjf
xandeycascardo: I grabbed two traces of the log, I think it will take me a while to puzzle out them. I posted them to the bug.16:42
cascardoxandey: thanks17:30
xandeycascardo: no problem17:38

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