[Bug 1922342] Re: HIrsute live session takes ages to boot on BIOS systems

[Thomas Schmitt]

Hi,

José Marinho wrote:
> I can't believe it... it boots fine again but once, twice, three
> times... and there is no MBR partition anywhere.

Let me make up a theory:

> - Burn on stick the iso that was builded with xorriso-1.5.5.
> - Boot it for the first time --> Success.

During this run of Ubuntu, casper did its "persistent partition creation",
as Steve Langasek puts it in bug 1899308.
This included a run of a GPT partition editor and then patching of MBR
partition slot 2 by the 16 bytes for the dummy partition with boot flag.

> - Boot it again --> Fails

The evil dummy partition does its work.

> sudo dd if=/dev/zero bs=1 count=16 of=/dev/sdX conv=notrunc seek=462

Now it is gone again.

What is not gone is the persistent GPT partition number 3. It covers the
formerly free space on the USB stick. In case of my "128 GB" stick:
  GPT start and size :   3  5505024  240254913

The "$NEW" ISO from xorriso-1.5.5 with mbr_force_bootable=off has only
two GPT partitions. ("$ORIG" has three. Number 3 covers 300 KiB of padding.)

> - Boot it again --> Success

Up to this first success it is no surprise.

To my theory, casper sees no need to add a "persistent partition" and
thus does not run the partition editor and does not write to MBR partition
slot 2.

> - The following boot attempts went fine too and no MBR partition 2 is
added.

No new MBR partition 2 = no boot problems.

Have a nice day :)

Thomas

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https://bugs.launchpad.net/bugs/1922342

Title:
  HIrsute live session takes ages to boot on BIOS systems

Status in casper package in Ubuntu:
  Confirmed
Status in casper source package in Impish:
  Confirmed

Bug description:
  First of all, I change the description of this bug because, thanks to
  Chris Guiver comments, I could check that the live session effectively
  works but it takes too long to complete. That's why I change the
  description of the bug from live session does not boot to live session
  takes ages to boot. I hope this is the best approach to this.

  I think the problem is the same as described here:
  https://discourse.ubuntubudgie.org/t/20-10-grub-error-can-t-find-
  command-grub-platform/4292. I can see prior to grub menu, briefly, the
  same error: Error can't find grub_platform. After the solution
  described below, this error is not showed and the system is able to
  boot.

  I try making the live usb using startup disk creator and with gnome-
  disks --> Restore disk image and get the same results.

  The live-usb has a gpt partition table instead of mbr like 20.04 live-
  usb has. That implies, I think, that the first one does not boot on
  BIOS systems and the second does.

  I try the same live-usb on an EFI laptop and it boots perfectly
  (perhaps it takes long time, but more less than in this case.

  If I try the solution described here:
  https://bugs.launchpad.net/ubuntu/+source/casper/+bug/1905491/comments/8
  then it works.

  ProblemType: Bug
  DistroRelease: Ubuntu 21.04
  Package: casper 1.461
  ProcVersionSignature: Ubuntu 5.11.0-13.14-generic 5.11.7
  Uname: Linux 5.11.0-13-generic x86_64
  NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
  ApportVersion: 2.20.11-0ubuntu61
  Architecture: amd64
  CasperMD5CheckResult: pass
  CasperVersion: 1.461
  CurrentDesktop: ubuntu:GNOME
  Date: Fri Apr  2 09:55:24 2021
  LiveMediaBuild: Ubuntu 21.04 "Hirsute Hippo" - Beta amd64 (20210331.1)
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=gl_ES.UTF-8
   SHELL=/bin/bash
  SourcePackage: casper
  UpgradeStatus: No upgrade log present (probably fresh install)

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