grub-mkrescue does not boot on older Macs as USB stick

grub-mkrescue does not boot on older Macs as USB stick

[Andrei Borzenkov]

I tested stock grub-mkrescue on MacBook 3,1 (late 2007, Core 2 Duo) and
iMac 9.1 (2009, same CPU) as USB stick. Neither boots; moreover,
inserting USB stick when boot manager is shown hangs system (it stops
reacting to mouse/keyboard); if stick is inserted during boot it never
gets as far as even showing boot manager.

Alexander reported something similar for 2007 Macs.

Stick is not detected even when inserted under OS X. MacBook runs 10.7
and reports that USB stick is not readable and suggests to iniitialize
it; iMac runs 10.9 and simply ignores it (may be I do not know where to
look).

I tried two different USB and one of them boots fine here on Dell
Latitude E5450 as EFI so I do not think both of them are defect. Of
course, they are not of finest quality ...

Same image as CD boots (I tried only MacBook but do not have reasons to
think that iMac will not boot). It presents three choices - two EFI and
one Windows. Windows ends up in presenting 1, 2 menu (without any
additional explanation) and not accepting any input. This is known
problem with legacy El Torito boot. First EFI boots; checking $cmdpath
it boots from HFS+ partition. Second EFI does not boot and falls through
to default boot order. When I try to chainload bootx64.efi manually (I
have dual OS X/openSUSE on it) it actually boots fine. I /think/ it
tries to load \EFI\Boot\boot.efi which is 32 bit only. I need to test
with removed boot.efi and with fat image.

I do not know if mkrescue image ever booted as USB on Mac. Alexander
says it does on modern Mac; anyone ever tried it on earlier models?

Re: [Bug-xorriso] grub-mkrescue does not boot on older Macs as USB stick

[Alexander E. Patrakov]

23.12.2015 01:02, Andrei Borzenkov пишет:
> I tested stock grub-mkrescue on MacBook 3,1 (late 2007, Core 2 Duo) and
> iMac 9.1 (2009, same CPU) as USB stick. Neither boots; moreover,
> inserting USB stick when boot manager is shown hangs system (it stops
> reacting to mouse/keyboard); if stick is inserted during boot it never
> gets as far as even showing boot manager.
>
> Alexander reported something similar for 2007 Macs.
>
> Stick is not detected even when inserted under OS X. MacBook runs 10.7
> and reports that USB stick is not readable and suggests to iniitialize
> it; iMac runs 10.9 and simply ignores it (may be I do not know where to
> look).

Thank you for looking into this. The description does match what was 
communicated to me by the person who owns that 2007 Mac.

I have compiled grub as of git revision a9399f2 on my virtual machine, 
with the same options as Debian does. Actually, I used their packaging 
minus all patches and minus 915resolution add-on. So, I will be able to 
test any further patches on my zoo of machines, too.

The first thought, though, is related to the fact that the Porteus Kiosk 
image uses partitions aligned to 1 MB. It may be a good idea to force 
this on grub-mkrescue command line and test-boot the result.

The second thought is that they built grub with a lot more preloaded 
modules, and removed boot.efi from the EFI image. Instead, they put a 
startup.nsh script there, which tries to run bootia32.efi and bootx64.efi.

-- 
Alexander E. Patrakov

Re: grub-mkrescue does not boot on older Macs as USBstick

[Thomas Schmitt]

Hi,

Alexander E. Patrakov wrote:
> The first thought, though, is related to the fact that the Porteus Kiosk
> image uses partitions aligned to 1 MB. It may be a good idea to force this
> on grub-mkrescue command line and test-boot the result.

That would be xorriso -as mkisofs options

  -partition_cyl_align on -partition_hd_cyl 64 -partition_sec_hd 32


Did you note the embedded configuration snippet at the end of
the file /EFI/BOOT/bootx64.efi in the Porteus EFI partition ?

  search --file --set=root /docs/kiosk.sgn
  set prefix=($root)/boot/isolinux/efi

(One should not get confused by the directory name "isolinux".)

Your "minimal.iso" does not have such strings in its bootx64.efi
or bootia32.efi.

In bootia32.efi of debian-8.2.0-i386-netinst.iso :

  search --file --set=root /.disk/info
  set prefix=($root)/boot/grub
  source $prefix/i386-efi/grub.cfg

In bootx64.efi of debian-8.1.0-amd64-netinst.iso :

  search --file --set=root /.disk/info
  set prefix=($root)/boot/grub
  source $prefix/x86_64-efi/grub.cfg

They all search for files in the ISO, not in the EFI partition.
I understand Debian hops onto the ISO's GRUB2 config for menu display.
(Does Porteus just boot a kernel without further menu ?)


Have a nice day :)

Thomas