On Sun, Apr 21, 2019 at 03:43:52PM +0200, Thomas Schmitt wrote: > Hi, > > this is about how exactly to solve a diagnosed and worked-around problem. > > Guix is one of the few distros which make their installation ISOs by > help of grub-mkrescue. The EFI boot manager of an old Macbook got stuck > when such an ISO was presented on USB stick. I.e. it not only did not > boot the ISO but showed no other EFI partitions either. > > A Debian Live 9 ISO does not impose such a problem. > The same Guix ISO on DVD rather than USB stick works well, too.
How do you create USB stick from ISO image? Have you tried latest Guix image? > The owner of the machine is Florian Pelz (Cc'ed). He characterizes it as: > MacBook Pro (13-inch, Mid 2010) > MacOS Yosemite reports: > Model Name: MacBook Pro > Model Identifier: MacBookPro7,1 > Boot ROM Version: MBP71.003F.B00 > SMC Version (system): 1.62f7 > > During a longish bug hunt it turned out that the decisive difference > is the first block of the FAT filesystem image which Debian creates by > mkfs.fat whereas grub-mkrescue creates it by mformat. > > The mformat-made image has an MBR partition table entry which claims the > whole image as partition 1: > > Device Boot Start End Sectors Size Id Type > /mnt/iso/efi.img1 * 0 2879 2880 1.4M 1 FAT12 > > If this partition entry is zeroed, then the EFI boot manager works even > when the USB stick with this modified ISO is plugged in. Numbers here and in another email suggest that this is a floppy image. And floppy images do not have MBR. They have something called boot sector which is a bit different thing. I have a feeling that simply Macs tested by you does not like floppy images. If you create regular HDD images then probably everything will work. Daniel _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
