On Monday, 18 April 2022 at 12:17, Thomas Schmitt wrote:
Hi,
Dominik 'Rathann' Mierzejewski wrote:
> > > Dell XPS 15 L502X 8GB RAM (BIOS only)
BIOS-only on a laptop might mean the firmware quirk which demands
to see the "boot/active" flag at some MBR partition table slot.
See a thread of grub-bug (and later grub-devel) from 2015/16
https://marc.info/?l=grub-bug&m=145052506901159&w=2
where Alexander E. Patrakov wrote:
"Subject: [bug #46716] Protective MBR partition is not marked as bootable
[...]
Changing the byte at offset 0x1be to 0x80 in the resulting iso makes
it bootable on such boards."
This led to the creation of xorrisofs option --mbr-force-bootable in
xorriso-1.4.3.
Does the following bash hack "repair" the USB stick so that it boots on
the affected machine ?
echo $'\x80' | dd of=/dev/sdX conv=notrunc bs=1 seek=446 count=1
No, it doesn't. Still getting "Operation System not found".
FWIW, I can see the following messages in dmesg when inserting the stick
into another machine:
[18881.575576] GPT:Primary header thinks Alt. header is not at the end of the disk.
[18881.575580] GPT:1334219 != 15974399
[18881.575582] GPT:Alternate GPT header not at the end of the disk.
[18881.575583] GPT:1334219 != 15974399
[18881.575584] GPT: Use GNU Parted to correct GPT errors.
[18881.575593] sdc: sdc1 sdc2 sdc3
[18881.598493] sd 9:0:0:0: [sdc] Attached SCSI removable disk
[18881.943729] ISO 9660 Extensions: Microsoft Joliet Level 3
[18881.945322] ISO 9660 Extensions: Microsoft Joliet Level 3
[18881.946584] ISO 9660 Extensions: RRIP_1991A
[...]
xorrisofs option --mbr-force-bootable may be added to the
grub-mkrescue
arguments. If we indeed face this bug, then a grub-mrescue ISO with EFI
equipment should not boot on the affected machine, unless this extra
option was given at production time.
I'll try the grub2-mkrescue ISO next.
Regards,
Dominik
--
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