[Bug 1206691] Re: crashkernel setting rarely works on a system with little memory

[Brian Murray]

** Summary changed:

- crashkernel setting rarely works
+ crashkernel setting rarely works on a system with little memory

** Changed in: grub2 (Ubuntu)
   Importance: Undecided => Medium

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Title:
  crashkernel setting rarely works on a system with little memory

Status in “grub2” package in Ubuntu:
  Incomplete

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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