Re: GPT boot has less features than legacy MBR-based one (Was: UEFI, loader.efi and /boot.config)

> On Sat, Jan 19, 2019 at 9:00 AM Rodney W. Grimes <
> freebsd-rwg_at_pdx.rh.cn85.dnsmgr.net> wrote:
> 
> > >
> > > On January 19, 2019 at 2:52:28 AM, Lev Serebryakov (lev_at_freebsd.org
> > (mailto:lev_at_freebsd.org)) wrote:
> > >
> > > > I have never seen such item in BIOS Setup. I've checked two MoBos now
> > (one is
> > > > Supermicro X9something and other is brand-new Goldmont-based Chinese
> > MiniPC
> > > > like Intel NUK): both have one knob in setup about boot type
> > > > (Legacy/UEFI/Auto) and if UEFI is selected, Supermicro MoBo (but not
> > Chinese
> > > > one) could be booted to "UEFI Console" which is not documented
> > anywhere.
> > > >
> > > > Ok, I've checked my desktop Asus Z170-A, but it is graphical and I
> > could
> > > > not find or understand anything in this home-rown UI with crazy-fast
> > mouse.
> > > >
> > >
> > > On ASUS systems you normally press F8 during POST to bring up the boot
> > menu, and F11 on Supermicro systems.
> >
> > ASUS should learn to put that stuff on screen... like everyone else.
> > I've been hitting the delete and going to the bios/boot tap which
> > also has a boot selection screen on one of my machines because I
> > did not know F8 existed.
> >
> 
> I've been generally reluctant to add old-style boot0 selection to UEFI
> stuff. The BIOS already does it, so we don't need to. I've not needed it at
> all.

The BIOS does NOT do what our boot0 does, I have seen no BIOS that
well allow me to select a partition on a drive, you can only select
the drive.

I think this is the feature that Lev is missing, and I am sure
others shall miss it to.

IIRC whistle used a version of this so you could install a new system
to partion 2, keeping your current system in partion 1, and changing the
active back and forth.  If we have lost that basic functionality with
the growth of GPT and UEFI that is a sad day.

> 
> However, we start the boot in lua. We already allow an interruption of
> loader.efi, so it would be super easy (assuming we got the lua bindings
> right) to implement something that would show you all the BootXXXX envs and
> let you select one to boot instead. We already have the ability to
> interrupt the boot loader. It would also be trivial to implement a 'efiboot
> XXXX' command to give that to you in cli mode. Both would set BootNext to
> XXXX and exit. We already have a menu, we could just add it to that. This
> would solve the hassles people are having with their BIOS (either because
> it's incomplete or hides the functionality too well) and would obviate the
> need to make boot1.efi do the selection (which has issues of its own due to
> boot1's limited scope).

Loader and such is far too late... as part of what the boot0 mbr gets you
around is when your loader in the new partition is what is stopping you
from getting booted because it got screwed up.

> The only drawback here is that we'd not be able to create new boot envs in
> the loader, or you'd need to create a new one if you haven't yet run
> efibootmgr(8), but if that's really an issue, someone will write code to
> cope.
> 
> Warner

-- 
Rod Grimes                                                 rgrimes_at_freebsd.org