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

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Am Fri, 18 Jan 2019 14:17:29 -0700
Warner Losh <imp_at_bsdimp.com> schrieb:

> On Fri, Jan 18, 2019 at 2:11 PM Emmanuel Vadot <manu_at_bidouilliste.com>
> wrote:
> 
> > On Fri, 18 Jan 2019 22:50:31 +0300
> > Lev Serebryakov <lev_at_FreeBSD.org> wrote:
> >  
> > > On 18.01.2019 22:35, Rodney W. Grimes wrote:
> > >  
> > > >>> errm.. you press a key and enter device and or loader path. if it is  
> > not working - the code is there to be fixed.  
> > > >>  And loader looks to "bootme" attribute and try to boot from partition
> > > >> which has one, even if it is loaded from other partition itself.
> > > >>  
> > > >>> GPT does not have the concept of active partition.  
> > > >>  It has "bootme" / "bootonce" attributes. And [zfs]gptboot doesn't  
> > have  
> > > >> any tools to set these attributes, AFAIK. Same for UEFI boot code.  
> > > >
> > > > The gpart(8) command is used to set/unset these.  
> > >  gpart need booted system. NanoBSD typically have two "system"
> > > partitions, "old" (previous) and "new" (current). After upgrade they
> > > switched (new code is written to "previos" partition and bootable
> > > atteibute is set to it, "active" in case of MBR and "bootme" in case of
> > > GPT).
> > >
> > >   If this new partition has problems and could not be booted, it is hard
> > > to boot from "old" (previous) one. MBR + boot0 could (interactively)
> > > change active partition before system is booted, and this problem could
> > > be solved with one keypress: you select old partition on boot.
> > >
> > > --
> > > // Lev Serebryakov
> > >  
> >
> >  With UEFI Boot* variable you could do :
> >
> >  - Update previous partition and set BootNext to it
> >  - If it fail next boot will be on current partition due to BootOrder
> >  - If it succeed, change the BootOrder to have the new partition first.
> >  
> 
> Also most UEFI BIOSes I've used (which isn't a lot) allow one to choose
> which BootXXXX variable to use to boot. Some will even create new BootXXXX
> variables that they use when you choose a raw device to boot from.
> 
> There's other people that have efi programs that will pop up a menu for you
> to select a particular BootXXXX to use. They then set BootNext and exit.
> I've not used any of these personally.
> 
> But this whole thread tells me we need to rewrite the boot section of our
> handbook.

Oh, yes, please, please!
Thanks in advance!

oh

> 
> Warner
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