Merge lp:~xnox/debian-cd/unbreak-grub2-hybrid-iso into lp:~ubuntu-cdimage/debian-cd/ubun3
Status: | Merged | ||||
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Merged at revision: | 2078 | ||||
Proposed branch: | lp:~xnox/debian-cd/unbreak-grub2-hybrid-iso | ||||
Merge into: | lp:~ubuntu-cdimage/debian-cd/ubun3 | ||||
Diff against target: |
20 lines (+10/-1) 1 file modified
tools/boot/groovy/boot-amd64 (+10/-1) |
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To merge this branch: | bzr merge lp:~xnox/debian-cd/unbreak-grub2-hybrid-iso | ||||
Related bugs: |
|
Reviewer | Review Type | Date Requested | Status |
---|---|---|---|
Steve Langasek | 2020-07-08 | Approve on 2020-07-08 | |
Michael Hudson-Doyle (community) | 2020-07-08 | Approve on 2020-07-08 | |
Ubuntu CD Image Team | 2020-07-08 | Pending | |
Review via email:
|
Michael Hudson-Doyle (mwhudson) wrote : | # |
Dimitri John Ledkov (xnox) wrote : | # |
Adding an ESP sounds fine, but I'm not sure why we bother with -eltorito-alt-boot -e boot/grub/efi.img.
Surely we only need 3 grubs: -b eltorito one, the hybrid mbr one, and the one inside the ESP.
Michael Hudson-Doyle (mwhudson) wrote : | # |
That's for the cdrom-uefi boot - that's still a wacko el torito thing, it
doesn't look at the partition table (at least according to the stuff I read)
On Wed, 8 Jul 2020, 22:46 Dimitri John Ledkov, <email address hidden>
wrote:
> Adding an ESP sounds fine, but I'm not sure why we bother with
> -eltorito-alt-boot -e boot/grub/efi.img.
>
> Surely we only need 3 grubs: -b eltorito one, the hybrid mbr one, and the
> one inside the ESP.
> --
>
> https:/
> You are reviewing the proposed merge of
> lp:~xnox/debian-cd/unbreak-grub2-hybrid-iso into
> lp:~ubuntu-cdimage/debian-cd/ubuntu.
>
Steve Langasek (vorlon) wrote : | # |
I'm not happy with the ESP being duplicated and want us to follow through on this, but approving for now to unbreak the images.
This is definitely an improvement (as in, the ISOs boot now in all of {legacy, uefi}x{ cdrom,disk} ) so we should merge it.
This and recent changes have the side effect of making the ISOs bigger, because each of the four boot modes described above gets its own copy of grub. In older images, legacy-disk boots used the 432 byte (!) isohdpfx.bin to jump to the grub in the el torito boot image for legacy boot and the MBR EFI partition used by uefi-disk pointed at the same data as the el torito boot image for EFI. These tricks require creating overlapping partition tables though and the libisofs on focal, at least, doesn't let you do that (at least in my tests).
This is the best documentation I've found for all this btw: https:/ /wiki.osdev. org/El- Torito.
I might propose a follow on commit that adds a *lot* of comments ...