Re: workaround install boot on btrfs with windows partition scheme

[Andrei Borzenkov <arvidjaar@gmail.com>]

В Sun, 2 Nov 2014 15:11:29 -0700
Chris Murphy <lists@colorremedies.com> пишет:

> 
> On Nov 1, 2014, at 11:27 PM, Andrei Borzenkov <arvidjaar@gmail.com> wrote:
> 
> > В Sat, 1 Nov 2014 14:35:57 -0600
> > Chris Murphy <lists@colorremedies.com> пишет:
> >> 
> >> Why not have a dedicated partition with MBR type code for core.img, equivalent to BIOSBoot currently used on GPT? freedesktop.org has a proposal to use type code 0xEA for this purpose (in part). The boot.img code in the MBR can arbitrarily jump to any LBA, so 0xEA doesn't need to be a primary partition does it?
> >> 
> > 
> > It is rarely needed in simple cases; in complicated cases (btrfs or
> > LVM) we already have space dedicated for core.img. It seems more
> > logical to use this space.
> 
> Well actually it isn't rare in simple cases. The most common case on Linux is booting from ext which grub won't embed to either without --force.xz_dec_lzma2

We are discussing installation in MBR here, not in partition. 

> So we have to have core.img embedded somewhere else. UEFI it's a fixed
 location. BIOS+GPT it's a fixed location. Only on MBR is it in an
 unreserved location or forcibly embedded - that's really  where the
 problem is. It seems a lot simpler to constrain the MBR options down
 to only a reserved partition just like elsewhere where it's now much
 simpler because it can only properly go in one location.
> 
> 
> > Also you still need to tell grub-setup to use this special partition at
> > which point why not extend it to support arbitrary location for
> > core.img? It could be made check partition type and not refuse to
> > install on raw partition for special 0xEA type then as a bonus.
> 
> I never tell grub-setup to use BIOSboot partition type. It always just finds it automatically.
> 

I do not really trust anyone respect partition types on MBR to be
honest. So I would rather avoid blindly overwriting anything without
explicit user's consent.