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Hi all,
this is a copy paste from a mailing list thread. Since I didn't receive any reply there, I want to try my luck here.
Normally I would rephrase and reformat it, but since I am currently suffering from RSI issues, I just copy-pasted it.
Thanks for your understanding!
====
Hi all.
I think I need some help with debugging an issue I have.
I recently bought an "Apple Magic Trackpad 2" for reducing strain on my
hand (since I have some RSI[0] issues currently), which is supported in
Linux since version 4.20[1].
After connecting it to my laptop it worked instantly at first, but
"sometimes" un- and replugging the trackpad crashes my system. Often it
works fine, but every now and then it triggers `general protection
faults` (often while opening big applications like Firefox), causes my
status bar to hang up, and usually ends in a freeze. Sometimes, just
before the freeze I get thrown back to the console and see a kernel
panic at the end of the log.
The laptop is a Thinkpad X200 running stock BIOS, Arch Linux and sway,
with microcode updates enabled. I could also reproduce the issue with
Gnome on Wayland. On Xfce I could not reproduce the issue, and also not
on Fedora (which I installed on the same laptop to the same SSD, for
testing).
I'm using the trackpad only via the USB cable, not via bluetooth.
Attached is a snippet from the dmesg output with debug logging enabled
(appended `debug` on the kernel cmdline) showing some of the protection
faults. I uploaded the full dmesg output here [2]. In this specific
dmesg output, most of the protection faults happened concurrently while
I was opening Firefox (several times to provoke the crash). A photo of
the kernel panic can be found here [3].
This kernel bug report[4] and related arch report[5] seem related to the
issue, maybe it's even the same issue? However, the kernel bug report
mentions that the issue only affects linux >=5.8.7. In my case, I could
reproduce the issue with the following linux versions (installed from
the Arch Linux archive):
4.20.0
4.20.1
4.20.3
4.20.7
5.0.0
5.0.13
5.4.74
5.2.0
5.8.6
5.8.7
5.8.8
5.9.2, 5.9.4
5.10rc-2
The USB ID of the trackpad is 05ac:0265.
Because I'm very inexperienced with kernel debugging I would appreciate
any help/pointers to what would be wise to test next. If this is likely
to be an issue with the Linux kernel and not arch-related (unsure, since
I could not reproduce it on other distros), please tell me so and I will
post to the kernel bug tracker instead.
Thanks!
mearon
[0]: https://web.eecs.umich.edu/~cscott/rsi.html
[1]: https://git.kernel.org/pub/scm/linux/ke … c5fdb23a4b
[2]: https://dpaste.com/2QEXCGV5Z.txt
[3]: https://0x0.st/idkz.jpg
[4]: https://bugzilla.kernel.org/show_bug.cgi?id=209239
[5]: https://bugs.archlinux.org/task/67860
Last edited by mearon (2020-11-09 20:19:12)
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Just for the record, someone else was debugging this a few days later:
https://bugzilla.kernel.org/show_bug.cgi?id=210241
And proposed a patch, which fixes the issue for both them and me:
https://patchwork.kernel.org/project/li … ke@web.de/
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