On Sat, Apr 20, 2019 at 06:32:07PM +0200, Thomas Schmitt wrote:
> We still need to find out whether the partition entry is the culprit.
> So please do the experiment with the Guix EFI partition image in
> partition 2 of the USB stick and
> 
>    dd if=/dev/zero bs=1 count=16 seek=446 of=/dev/sdc2
> 

Yes, this fixes the issue.


I tried current Git guix master with ludo's reproducibility patches.
Of course with the reproducibility patches the Macbook still gets
stuck before booting.

> Yes.
>   http://git.savannah.gnu.org/cgit/grub.git/tree/util/grub-mkrescue.c#n812
> has:
>       rv = grub_util_exec ((const char * []) { "mformat", "-C", "-f", "2880", "-L", "16", "-i",
>             efiimgfat, "::", NULL });
> 

I added "-k" to it (see attached ugly Guix patch).  This fixes the
issue for me.  (I do not know if this has other unintended side
effects and I can only try on other Macbooks next week.)

Regards,
Florian