Re: [Xen-devel] pygrub not starting first menuentry in Fedora 30

[George Dunlap <dunlapg@xxxxxxxxx>]

On Mon, May 13, 2019 at 11:25 AM Steven Haigh <netwiz@xxxxxxxxx> wrote:
>
> There seems to be some changes in Fedora 30 that cause the second boot
> entry in grub.cfg to be booted instead of the first.
>
> This means that Fedora 30 systems either always boot into an older
> kernel, or in the case of systems with only one kernel installed, the
> rescue image.
>
> There also seems to be some new issues with the move to BLSCFG -
> however it seems a new requirement is to have
> GRUB_ENABLE_BLSCFG="false" in /etc/default/grub. This causes
> grub2-mkconfig to work correctly and spit out a grub.cfg file that
> pygrub can then use.
>
> Is this a bug in pygrub, or a problem with how Fedora 30 generates a
> grub.cfg?
>
> I tried to pick through pygrub - but couldn't quite follow the python
> logic to see where the default boot option is selected.

AFAICT, the basic issue is that pygrub is a partial re-implementation
of grub, and hasn't re-implemented the blscfg functionality.

The *most robust* solution going forward is always going to be to use
grub-xen (AKA pvgrub2) instead of pygrub.  grub-xen is a port of the
actual grub project to run as a PV guest, and so will always be  the
most compatible with upstream grub.

Not sure who's "in charge" of pygrub enough to teach it how to use blscfg.

 -George

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