On 10/20/25 15:10, Andrei Borzenkov wrote: > 20.10.2025 21:22, Demi Marie Obenour wrote: >> On 10/20/25 14:20, Andrei Borzenkov wrote: >>> 20.10.2025 21:02, Demi Marie Obenour wrote: >>>> On 10/20/25 13:57, Andrei Borzenkov wrote: >>>>> 20.10.2025 20:33, Demi Marie Obenour wrote: >>>>>> On 10/19/25 11:36, Feli Flitzberg wrote: >>>>>>> Hi, long time watcher, first time poster. If the bootloader supports >>>>>>> the Discoverable Partitions Specification, all that's needed is the >>>>>>> correct partition GUID assigned to every partition. After that, you >>>>>>> don't need to pass any partitions or use /etc/fstab as the bootloader >>>>>>> will read the disk it came from to mount everything. The only major >>>>>>> limitation is that your bootloader partition MUST live on the same disk >>>>>>> as root and usr, otherwise they won't be found. Hope this helps! >>>>>> >>>>>> How can the OS know which block device the system was booted from? >>>>>> >>>>> >>>>> >>>>> Bootloader compliant with BLI sets the LoaderDevicePartUUID EFI >>>>> variable. Otherwise I assume it possible to get the current boot entry >>>>> number from the BootCurrent EFI variable and parse the corresponding >>>>> BootXXXX entry. >>>> >>>> Is this EFI variable the partition table UUID (which identifies a device) >>>> or a partition UUID (which does not)? >>> >>> It is what is printed by lsblk as partuuid. >> >> Unfortunately this isn't what is needed. Looks like UEFI variable >> storage is the best option. > > Partition UUID is (supposed to be) unique for every partition, so it > most certainly allows one to identify the device to which it belongs.
I mixed up partition UUID and partition *type* UUID. What is the best way to use it? The most obvious one requires that whenever a block device appears, one checks if either: - This has the correct partition UUID, and a device with the same diskseq and the correct partition type UUID has appeared. - This has the correct partition type UUID, and a device with the same diskseq and the correct partition UUID has appeared. Is there a simpler option? -- Sincerely, Demi Marie Obenour (she/her/hers)
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