[Bug 1800722] Re: EFI booting + /boot on LVM == inaccessible boot menu

[Launchpad Bug Tracker]

This bug was fixed in the package grub2 - 2.02+dfsg1-5ubuntu9

---------------
grub2 (2.02+dfsg1-5ubuntu9) disco; urgency=medium

  [ Steve Langasek ]
  * debian/patches/quick-boot-lvm.patch: If we don't have writable
    grubenv and we're on EFI, always show the menu.  Closes LP: #1800722.

  [ Mathieu Trudel-Lapierre ]
  * debian/patches/mkconfig_leave_breadcrumbs.patch: make sure grub-mkconfig
    leaves a trace of what files were sourced to help generate the config
    we're building.

 -- Mathieu Trudel-Lapierre <cyphermox at ubuntu.com>  Mon, 07 Jan 2019
17:32:01 -0500

** Changed in: grub2 (Ubuntu)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1800722

Title:
  EFI booting + /boot on LVM == inaccessible boot menu

Status in grub2 package in Ubuntu:
  Fix Released

Bug description:
  Because EFI does not support instantaneous read of modifier keys (i.e.
  holding down shift at boot), the only way to reliably show a boot menu
  is by letting the system boot, interrupting the boot, and letting the
  menu be displayed because 'recordfail' has been set.

  If /boot/grub is on LVM, recordfail does not work, because grub
  doesn't have write support on LVM, so saveenv doesn't work.  Indeed,
  from the grub.cfg on such a system, the recordfail function is written
  as:

  function recordfail {
    set recordfail=1
    # GRUB lacks write support for lvm, so recordfail support is disabled.
  }

  The interaction of these two limitations means that systems with
  /boot/grub on LVM cannot reliably get a grub menu, ever.

  While I think that in the long term we should always put /boot/grub on
  the ESP (which means it will always be writable by grub), which is in
  fact what we did for Ubuntu Core, in the meantime I believe what we
  need to do here is always show the boot menu if we are booted under
  EFI and we have a non-writable grubenv.

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