On 2023-05-01, Pascal Hambourg wrote: > On Sun, 30 Apr 2023 17:37:13 -0700 Vagrant Cascadian > <vagr...@debian.org> wrote: >> On 2023-05-01, Steve McIntyre wrote: >> "ls" from the grub prompt did not show the other disk... >> ...until I made the second disk bootable from libvirt! >> Then grub now sees both disks, and boots fine! >> So this is possibly a quirk of the way libvirt exposes boot disks. > > Apparently. GRUB can only see disks exposed by the BIOS/UEFI/other > platform firmware. There are other known situations where a given > firmware may not expose some disks, including but not limited to: > - disks connected to a SATA controller card without a BIOS expansion ROM > - unsupported media types: USB other than the boot disk, NVMe, SD/MMC... > > The UEFI firmware on an old Intel board only had EFI drivers for the > SATA controller in IDE mode and lacked EFI drivers for AHCI and USB. It > has been reported that more recent boards had support for NVMe only in > EFI mode, not in legacy mode. ... >> Re-running grub-install /dev/vda from debian-installer rescue mode did >> *not* fix the issue for me > > Because there were two issues preventing GRUB from seeing the new PV: > - the disk was not exposed by libvirt BIOS > - the disk had an unsupported GPT partition scheme > > grub-install fixed only the second issue. Making the disk "bootable" in > libvirt was required to fix the first issue. > >> (though, now I am curious if dpkg-reconfigure >> grub-pc would do anything more?) > > As Steve wrote, dpkg-reconfigure also runs update-grub to rebuild > grub.cfg. AFAIK here the only difference with the old grub.cfg is > additional "insmod part_gpt" commands to load GPT support, but the > module must already be embedded in the core image so this addition is > not required.
Well, in my original bug report, grub.cfg did contain both: insmod part_gpt insmod part_msdos Although, maybe it is possible that was generated after running update-grub... Even though a perfectly reasonable stance is just to use a split /boot partition, I may keep experimenting with this to get greater confidence we really understand what went wrong. :) live well, vagrant
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