4.19-rc8 - debugging kernel issues - how do I get the logs off before my system crashes?

[Christopher Patti]

Hi all!

In my seemingly never-ending quest to get Ubuntu running well on my
Alienware 17 R5, I reported
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1796743 because in
any version of Ubuntu - 18.04, 18.10 etc, if you close the lid, the
machine crashes and gets put into a weird state when you open the lid
and hit the power button.
In that bug, they suggested I install the latest 4.19 upstream kernel,
which I did, and that DOES in fact fix the issue!
However, when I boot with 4.19-rc7/8 my system slows to a CRAWL and
eventually freezes up entirely after a time. So I reported
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1799180
I can find how to turn on verbose logging - add 'verbose' to the grub
command line, but once I've done that, how do I get the logs off the
box before it crashes? Or do I just power it off after the crash and
then wait long enough that I can see the missing time and start
looking there?
Trying to report a bug with ubuntu-bug suggests I should report this bug
upstream to bugzilla.kernel.org, but *their* ReportingBugs doc basically
says unless you identify the proper subsystem responsible for your bug
your issue is likely to be black-holed.
I'd really appreciate any thoughts from anyone on appropriate next
steps. I plan to keep digging until I get this system running ship shape
and Bristol fashion! :)
Thanks!
-Chris

[Ralf Mardorf via ubuntu-users]

how do I get the logs off the box before it crashes?

Is there an operating system able to run on this machine? If so, run
this operating system and get access to the Ubuntu install's partition
containing /var/log. IOW access the log files by running another
operating system.

If you should have another computer, consider to capture a netconsole
trace.

Trying to report a bug with ubuntu-bug suggests I should report this
bug upstream to bugzilla.kernel.org, but *their* ReportingBugs doc
basically says unless you identify the proper subsystem responsible
for your bug your issue is likely to be black-holed.

If it should be a tainted kernel, e.g. special proprietary drivers
should be required for the hardware, excepted of a graphics driver, they
anyway might ignore a bug report.