On Thu, 12 Mar 2026 00:17:05 -0400
Aaron Rainbolt <[email protected]> wrote:

> On Wed, 11 Mar 2026 21:32:04 -0400
> Aaron Rainbolt <[email protected]> wrote:

... snip ...

> I'm not sure if this is particularly safe, since it depends on the
> Raspberry Pi firmware only checking the second (or perhaps first two)
> partitions for GPT protective MBR partitions, and depends on the Linux
> kernel continuing to recognize a disk as GPT-formatted even if only a
> small part of it is covered by a protective partition. This might also
> not work on newer (or older) Raspberry Pi versions. But, with Debian
> Trixie, on a Raspberry Pi 4B with 8 GB RAM, this works. The
> alternative would be to switch to an MBR-only partition table, which
> is what grml-debootstrap currently does. This is probably safer in
> the long run, but maybe there are reasons to avoid this.
> 
> --
> Aaron

Small update, it looks like this is a case of the raspi-firmware
package in Trixie being too old. Raspberry Pi OS is able to boot (well,
load the kernel and initramfs anyway, I didn't get bootup to work all
the way, but not because I couldn't, just because I didn't) with a
hybrid MBR configuration similar to what the Trixie cloud image is
using. Furthermore, the hybrid MBR layout also works on a Trixie cloud
image if I copy over the start*.elf and fixup*.dat files from a
Raspberry Pi OS firmware partition to the Trixie cloud image firmware
partition.

I'll be filing a bug report in Debian for this in the near future.

--
Aaron

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