Fix different behaviour between usb and cd in efi #135
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this supposedly increases compatibility when booting from usb Mark the current El Torito boot image (see options -b and -e) in an actually invalid GPT as partition of type Basic Data. This works only with -isohybrid-mbr and has the same impact on the system area as -efi-boot-part. It cannot be combined with -efi-boot-part or -hfsplus. The first three boot images which are marked by GPT will also show up as partition entries in MBR. The MBR partition of type 0xEF is what actually is used by EFI firmware for booting from USB stick. The MBR partition for PC-BIOS gets type 0x00 rather than 0x17 in this case. Often the further MBR entries are the ones which actually get used by EFI. Signed-off-by: Itxaka <itxaka@kairos.io>
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Codecov ReportAll modified and coverable lines are covered by tests ✅
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Signed-off-by: Itxaka <itxaka@kairos.io>
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Itxaka
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Dec 10, 2024
| "-boot_image", "any", "platform_id=0xef", | ||
| "-boot_image", "any", "emul_type=no_emulation", | ||
| "-boot_image", "any", "efi_path=" + IsoEFIPath, // Tell where the efi path is |
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this is just an improvement over what we had.
Before:
- uefi.img in the disc
- second partition in the disc with uefi contents
Now:
- just the uefi.img in the disc
Signed-off-by: Itxaka <itxaka@kairos.io>
Co-authored-by: Mauro Morales <mauro.morales@spectrocloud.com>
Itxaka
commented
Dec 11, 2024
Signed-off-by: Itxaka <itxaka@kairos.io>
mauromorales
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Dec 11, 2024
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Seems that the actual issue was not that the USB is not recognized, but the usb boots and it gets a grub shell because it cannot load the default grub.cfg for efi.
This seems to be a side issue of how efi booting works differently from livecd or usb in grub.
Looks like when booting from livecd, the efi artifacts are loaded from the efi image file BUT the livecd is mounted as root for grub.
When booting from usb it seems like the efi artifacts are loaded from the efi image AND the efi image is mounted as root for grub.
In both cases, grub is hardcoded to search for the grub config in /EFI/boot/grub.cfg (so alongside the grubx64.efi file)
When we build the ISO we only copy those artifacts on the ISO root, so you got the /EFI/boot/grub.cfg directly accessible when booting from livecd.
But when booting from usb the livecd is ignored and only the contents of the uefi.img are in the root, so /EFI/boot/grub.cfg does not exists.
This is fixed by copying it to both places so it works on both boot methods.