SPDX-License-Identifier: LGPL-2.1+
Copyright (c) 2021 Valve.
############################ SteamOS Kdump
This is the first version of SteamOS Kdump infrastructure. The goal is to
collect data whenever a kernel crash is detected. There is a lightweight
collection, that only grabs dmesg, and a more complete setting to grab the
whole (compressed) vmcore. The tunnings are available at /etc/default/kdump.
After installation and a reboot, things should be all set EXCEPT for GRUB
config - please check the CAVEATS/INSTRUCTIONS section below. Notice the
package is under active development, this one being a kind of "Proof Of Concept"
still - improvements are expected in the near future. Thanks for testing!!!
CAVEATS / INSTRUCTIONS
(a) For now, we don't automatically edit any GRUB config, so the minimum
necessary action after installing this package is to add "crashkernel=160M"
to your GRUB config in order subsequent boots pick this setting and do reserve
the memory, or else kdump cannot work. The memory amount was empirically
determined - 128M wasn't enough and 144M is unstable, so 160M seems good enough.
(b) It requires (obviously) a RW rootfs - we've used tune2fs in order to make
it read-write, since it's RO by default. Also, we assume the nvme partition
scheme is default across all versions and didn't change with new updates
for example - kdump relies in mounting partitions, etc.
(c) Due to a post-transaction hook executed by libalpm (90-dracut-install.hook),
unfortunately after installing the kdump-steamos package all initramfs images
are recreated - this is not necessary, we're thinking on how to prevent that,
but for now be prepared: the installation take some (long) minutes due to that ={
(d) Unfortunately makedumpfile form Arch Linux is not available on official
repos, only in AUR - and it doesn't build with zstd, which allows great and
fast compression. So, we're hereby packing the binary with all the scripts,
which is a temporary workaround and should be resolved later - already started
to "lobby" for package inclusion in the official channels and also we're trying
to to add zstd support:
TODOs (for now - we expect to have more after some testing by the colleagues)
(1) We'd like to be able to automatically edit GRUB and recreate its config
file - after some future discussion on the proper parameters, this is expected
to be added to the package.
(2) Hopefully we can fix/prevent the unnecessary re-creation of all initramfs
images - this happens due to our package installing files on /usr/lib/dracut/modules.d
which is a trigger for this initramfs recreation.
(3) We have a "fragile" way of determining a mount point required for kdump;
this is something to improve in order to make the kdump more reliable.
(4) Add a more reliable reboot mechanism - we had seen issues with "reboot -f"
in the past and relying in sysrq reboot as a quirk managed to be a safe option,
so this is something to think about here. Should be easy to implement.
(5) Maybe a good idea would be to allow creating the minimum image for any
specified kernel, not only for the running one (which is what we do now).
Low-priority idea, easy to implement.
