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kdump_load.sh, kdump.etc: Introduce GRUB auto-setting support

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With this addition, kdump-steamos is now capable of editing grub.cfg
to automatically add the required kdump parameters, in case kdump
is used. If Pstore ends-up being used and the grub.cfg was mofified
by kdump-steamos automatically, we're also able to undo the change
and save users from memory waste.

Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
This commit is contained in:
Guilherme G. Piccoli
2022-02-11 12:39:24 -03:00
parent 0dd74fc114
commit ea5f104c70
4 changed files with 69 additions and 30 deletions
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35
README.md
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@ -51,9 +51,9 @@
# can choose Kdump instead of Pstore (USE_PSTORE_RAM), and if using Kdump,
# collect the full vmcore (FULL_COREDUMP). The vmcore is not stored in the
# ZIP file, but it's saved in "/home/.steamos/offload/var/kdump/crash/".
# NOTICE that, if Kdump is used instead of Pstore, the following flags are
# needed in GRUB cmdline: "crashkernel=192M crash_kexec_post_notifiers" and
# a regular reboot is necessary.
# NOTICE that, if Kdump is used instead of Pstore (either per user's choice
# or due to some failure in Pstore), a reboot is necessary before kdump is
# usable, in order to effectively reserve crashkernel memory.
#
# 6. Error and succeeding messages are sent to systemd journal, so running
# 'journalctl | grep kdump' would hopefully bring some information. Also,
@ -64,14 +64,14 @@
# ############################## DETAILS ##################################
# CAVEATS / INSTRUCTIONS
# ###########################################################################
# (a) Currently, we don't automatically edit GRUB config; see TODO (1) below.
# This is not required if Pstore is used (which is the default).
# (a) We automatically edit GRUB config in case Pstore fails or if the user's
# choice is to use Kdump. But it requires one reboot in order the crashkernel
# memory is effectively reserved by kernel.
#
# In case Kdump is used, boot-time reserved memory is required, check step (5)
# in the HOW-TO above. The memory amount was empirically determined - setting
# 144M wasn't enough and 160M is unstable, so 192M seems good enough. This
# amount might change in future kernel versions, requiring tests using the
# approach suggested in the step (4) above.
# In case Kdump is used, the crashkernel necessary memory was empirically
# determined; setting 144M wasn't enough, 160M is unstable, so 192M seems
# good enough. This amount might change in future kernel versions, requiring
# tests using the approach suggested in the step (4) above.
#
# (b) The kdump-steamos package requires a RW rootfs in case it's not currently
# embedded in your image. Users can make use of 'tune2fs' or 'steamos-readonly'
@ -95,32 +95,29 @@
#
# TODOs
# ###########################################################################
# (1) We'd like to be able to automatically edit GRUB and recreate its config
# file - implementation tests are ongoing.
#
# (2) Would be interesting to have a clean-up mechanism, to keep up to N most
# (1) Would be interesting to have a clean-up mechanism, to keep up to N most
# recent ZIP log files, instead of keeping all of them forever.
#
# (3) Hopefully we can fix/prevent the unnecessary re-creation of all initramfs
# (2) Hopefully we can fix/prevent the unnecessary re-creation of all initramfs
# images - it happens due to our package installing files on directory
# "/usr/lib/dracut/modules.d" which triggers the unfortunate initramfs rebuild.
#
# (4) We have a "fragile" way of determining a mount point required for Kdump;
# (3) We have a "fragile" way of determining a mount point required for Kdump;
# this is something to improve maybe, in order to make the Kdump more reliable.
# Also in the list of fragile things, VDF parsing is...complicated. Something
# that would be nice to improve as well.
#
# (5) Pstore ramoops back-end has some limitations that we're discussing with
# (4) Pstore ramoops back-end has some limitations that we're discussing with
# the kernel community - right now we can only collect ONE dmesg and its
# size is truncated on "record_size" bytes, not allowing a file split like
# efi-pstore; thankfully we still can collect 2MiB dmesg, but hopefully we can
# improve that upstream.
#
# (6) Add a more reliable reboot mechanism - we had seen issues in the past
# (5) Add a more reliable reboot mechanism - we had seen issues in the past
# with "reboot -f", and relying in sysrq reboot as a quirk managed to be a safe
# option, so this is something to think about. Should be easy to implement.
#
# (7) Maybe a good idea would be to allow creating the minimum image for any
# (6) 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.
#