[Bug 1206691] Re: crashkernel setting rarely works

[David Medberry]

The actual problem is that the box hangs if there is not enough memory.
Unfortunately, I don't have console on this particular box either (as it
is an Azure virtual machine.) Using the "extrasmall" instances on Azure
provides only 768MB and the "small" which is default only provides
1.75G.

I'll see if I can reproduce the issue on a box (vm) that does have
console and provide the log if so.

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Title:
  crashkernel setting rarely works

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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