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[Bug 785394] Re: Hard-coded crashkernel=... memory reservation in /etc/grub.d/10_linux is insufficient


Agreed. It's not clear that there is *any* standard Ubuntu kernel
configuration that can boot in 64MB. And having that as a default is
worse than useless, because the crash-kernel's OOM prevents the system
from recovering automatically after a kernel crash.

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  Hard-coded crashkernel=... memory reservation in /etc/grub.d/10_linux
  is insufficient

Status in “grub2” package in Ubuntu:
Status in “kexec-tools” package in Ubuntu:
  In Progress

Bug description:
  Binary package hint: grub-pc

  This concerns grub-pc 1.99~rc1-13ubuntu3 in Ubuntu Natty.

  The /etc/grub.d/10_linux file contains this snippet:

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

  I am on a system with 2GB of RAM (reported as 2038MB), and according
  to the kernel startup messages, 64MB is reserved for the crash kernel.

  Unfortunately, this does not appear to be enough memory for the
  regular Ubuntu kernel to boot. I am attaching a kernel log obtained
  via serial cable; it shows the initial boot, a crash in the kernel's
  video-driver-related code, the subsequent crashkernel boot, and then
  an apparent "out of memory" kernel panic. (A side effect of the
  "double crash" is that the system is left unresponsive, requiring a
  manual reset instead of rebooting itself automatically.)

  If I double the memory numbers in the crashkernel=... argument, so
  that the reservation is 128MB, the system correctly goes on to attempt
  a vmcore dump and reboot.

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