[Bug 1918265] Re: Random boot failure with Ubuntu 20.04 / grub 2.04 and Hyper-V 2012r2

[Paul Chilton]

Having re-tested this with one particular VM that was failing, it
appears to be happy on any VLAN but 10 (which has most of my clients on
at the moment, including the Hyper-V server itself).

To add some more detail in case it's relevant, each server I have 2x LAN
Teams, one for the Windows 2016 use with a static IP on VLAN 10 and the
other dedicated to Hyper-V setup as a trunk port. Each LAN Team has 2x
10Gbps links.

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Title:
  Random boot failure with Ubuntu 20.04 / grub 2.04 and Hyper-V 2012r2

Status in grub2 package in Ubuntu:
  Confirmed

Bug description:
  Hi,

  We are experiencing some weird boot issues with Ubuntu 20.04 and
  Hyper-V 2012r2.

  In two cases the installation started successfully, as did the VM
  initial boot and then issues started to arise, where the boot process
  started to fail.

  grub start, the menu pop-up and then just after loading kernel and
  initrd (tried to put some echo(es) in the config the VM somehow reset
  and the menu pop-up back again.

  After a few of thoses either the VM shut-down or the boot is
  successfull, It seems completly random..

  Here it is captured on video:
    https://www.youtube.com/watch?v=5Bk3S-YGDZk

  If i setup a direct EFI-STUB boot of the kernel+initrd the boot
  process works every times.

  I suspected the "save_env/load_env" for a while but a stripped down
  grub.cfg give the same result..

  > insmod gzio
  > insmod part_gpt
  > insmod ext2
  > set root='hd0,gpt2'
  > if [ x$feature_platform_search_hint = xy ]; then
  >  search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2  94ebc17e-6aca-4e42-b489-b3eaa8a32d90
  > else
  >  search --no-floppy --fs-uuid --set=root 94ebc17e-6aca-4e42-b489-b3eaa8a32d90
  > fi
  > linux	/vmlinuz-5.8.0-44-generic root=/dev/mapper/ubuntu--vg-ubuntu--lv ro nosplash elevator=noop 
  > initrd	/initrd.img-5.8.0-44-generic
  > boot

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