[Bug 1206691] Re: crashkernel setting rarely works

[Seth Arnold]

Thanks for taking the time to report this bug and helping to make Ubuntu
better. We appreciate the difficulties you are facing, but this appears
to be a "regular" (non-security) bug.  I have unmarked it as a security
issue since this bug does not show evidence of allowing attackers to
cross privilege boundaries nor directly cause loss of data/privacy.
Please feel free to report any other bugs you may find.

** Information type changed from Private Security to Public

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Title:
  crashkernel setting rarely works

Status in “grub2” package in Ubuntu:
  New

Bug description:
  In the file /etc/grub.d/10_linux

  you will find:

      87	# add crashkernel option if we have the required tools
      88	if [ -x "/usr/bin/makedumpfile" ] && [ -x "/sbin/kexec" ]; then
      89	    GRUB_CMDLINE_EXTRA="$GRUB_CMDLINE_EXTRA crashkernel=384M-2G:64M,2G-:128M"
      90	fi

  However, I've not seen the 384M-2G:64M work since precise. It works
  fine if you bump it up to 128M (or just make it crashkernel=128M)

  It's not clear to me where to make this change:
  medberry at handsofblue:~/work/grub2/grub2$ find . -name 10_linux\* -print0 |xargs --null grep crashkernel
  ./.pc/ubuntu_failed_boot_menu.patch/util/grub.d/10_linux.in:# add crashkernel option if we have the required tools
  ./.pc/ubuntu_failed_boot_menu.patch/util/grub.d/10_linux.in:    GRUB_CMDLINE_EXTRA="$GRUB_CMDLINE_EXTRA crashkernel=384M-2G:64M,2G-:128M"
  ./.pc/ubuntu_gfxpayload_filter.patch/util/grub.d/10_linux.in:# add crashkernel option if we have the required tools
  ./.pc/ubuntu_gfxpayload_filter.patch/util/grub.d/10_linux.in:    GRUB_CMDLINE_EXTRA="$GRUB_CMDLINE_EXTRA crashkernel=384M-2G:64M,2G-:128M"
  ./.pc/ubuntu_linux_quiet.patch/util/grub.d/10_linux.in:# add crashkernel option if we have the required tools
  ./.pc/ubuntu_linux_quiet.patch/util/grub.d/10_linux.in:    GRUB_CMDLINE_EXTRA="$GRUB_CMDLINE_EXTRA crashkernel=384M-2G:64M,2G-:128M"
  ./.pc/ubuntu_recovery_nomodeset.patch/util/grub.d/10_linux.in:# add crashkernel option if we have the required tools
  ./.pc/ubuntu_recovery_nomodeset.patch/util/grub.d/10_linux.in:    GRUB_CMDLINE_EXTRA="$GRUB_CMDLINE_EXTRA crashkernel=384M-2G:64M,2G-:128M"
  ./.pc/ubuntu_vt_handoff.patch/util/grub.d/10_linux.in:# add crashkernel option if we have the required tools
  ./.pc/ubuntu_vt_handoff.patch/util/grub.d/10_linux.in:    GRUB_CMDLINE_EXTRA="$GRUB_CMDLINE_EXTRA crashkernel=384M-2G:64M,2G-:128M"
  ./util/grub.d/10_linux.in:# add crashkernel option if we have the required tools
  ./util/grub.d/10_linux.in:    GRUB_CMDLINE_EXTRA="$GRUB_CMDLINE_EXTRA crashkernel=384M-2G:64M,2G-:128M"

  as it appears so many times but the likeliest place is a new patch
  somewhere. Alternatively, having a way to modify this via something
  akin to grub.d/42_custom may work.

  (This may be considered a Denial of Service as a crash won't work
  without enough memory and may hang booting--but crashing in the first
  place is already a limited DoS....)

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