Re: [PATCH v2 08/12] kern: Make grub_error() more verbose

[David Michael]

On Fri, Mar 6, 2020 at 9:02 AM Didier Spaier <address@hidden> wrote:
> Le 06/03/2020 à 13:43, Daniel Kiper a écrit :
> > If we go that way then we have to care about them by the end of the
> > universe. And this means more and more issues like [1]. If somebody
> > wants to use new GRUB then he/she have to reinstall the machine or
> > something like that. IMO we should not care about users who do not want
> > upgrade their machines or whatnot. Or at least their choices cannot
> > impact GRUB development too much. And I think that this MBR constraint
> > is hindering the project too much at this point. So, as above...
> >
> > Sorry for being blunt...
>
> Sorry to be off topic... In case of a GUID partition table, if I
> understand the UEFI specification[1], as the first usable LBA should be
> greater than or equal to 34 for a 512 bytes block size or 6 for a
> 4096 bytes logical block size, it could begin after a gap of 24K.
>
> Then, if we assume that the first partition begins @ 1MiB, can't GRUB
> use the space unused between the first usable LBA and 1MiB instead of
> a Bios Boot partition, in case of "legacy" booting and a GPT? I ask as
> then a Bios Boot partition wouldn't be necessary any more.

It would be best to use a boot partition so the core.img space is
reserved by the GPT, but I once wanted to tack i386-pc GRUB onto an
existing UEFI GPT disk, so I wrote the commands that do what you're
describing here:

https://github.com/dm0-/installer/blob/master/examples/systems/fitpc.sh#L151-L178

I may be misremembering, but I think the core.img size was limited to
around half a megabyte, so it should be safe to write it to the unused
~1MiB before the first partition after the GPT.  But yes, using the
boot partition would probably be for the best if you are formatting a
new disk.

Thanks.

David