dropping various grub targets

[Steve Langasek]

Hi Ian,

On Wed, Oct 11, 2023 at 08:30:14PM +0100, Ian Bruntlett wrote:
> Hi Steve,

> I can read ubuntu-devel messages but can't post replies to it...

You can reply but replies will be held until moderated.

I am happy to post this message to ubuntu-devel with your permission, to
keep the thread together.

> On Wed, 11 Oct 2023 at 00:13, Steve Langasek <steve.langasek at ubuntu.com>
> wrote:

> > To be clear, it would make a lot of things easier if we did determine we
> > could drop not only BIOS boot support from our images, but also El-Torito
> > ISO boot support treating these images as only for flashing on USB drives.
> > It would remove one significant barrier for us adopting ubuntu-image for
> > the
> > mastering of our installer images.  But we should do the work to establish
> > that these things are no longer needed!

> How much work is involved in maintaining BIOS boot support for your images?

> I use various systems that are still BIOS based systems and losing BIOS
> support would be quite disappointing and bad for the environment.

> I *might* be able to help with keeping the BIOS boot support working. What
> exactly does it entail?

> I am mainly a C programmer who can write a bit of C++ who is planning to go
> deeply into C++ over the next couple of years.
> 
> Assembly language does not frighten me... much. My degree's project was
> written as a combination of 8086 assembler and 68000 assembler. But that
> was some time ago.

The context here is that our official images are built using a horrible,
terrible, multi-phase pipeline that's implemented in piles of shell script
with 20 years of history and we'd like to jettison the whole thing in favor
of ubuntu-image, which uses a declarative format for describing disk
layouts.

But.

- we have no language yet for describing ISO9660 filesystems as images
- expressing that for both BIOS and UEFI boot is more complicated than just
  for UEFI
- the only tool in existence that we know of that can get this right
  ("right") is xorriso and we would not necessarily want that as an external
  dependency (or be able to drive it to DTRT from ubuntu-image declarative
  yaml).

Also ubuntu-image is implemented in golang, so I'm afraid C and C++
experience doesn't help substantially here, sorry!

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                   https://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org