On Wednesday, 6 December 2023 17:34:08 GMT Marco Rebhan wrote: > On Wednesday, 6 December 2023 17:49:43 CET Victor Ivanov wrote: > > So, without knowing much about systemd-boot from the guide linked it > > seems to me that its implementation doesn't differ too much from this > > reasonably well established model, except for a few additional > > constraints which, based on my understanding, are: > > 1. You _must_ have an XBOOTLDR partition (functionally equivalent to > > "boot" above) _in addition to_ the ESP and cannot simply use "/boot" > > under your rootfs partition > > 2. XBOOTLDR partition _must_ be of GPT type 0xEA00 > > 3. XBOOTLDR partition _must_ have GUID set to > > "bc13c2ff-59e6-4262-a352-b275fd6f7172" > > 4. XBOOTLDR partition _must_ be formatted with a filesystem supported > > by your EFI BIOS with FAT32 being universally supported, though your > > particular EFI BIOS _might_ support others > > > > I say "must" as it appears to be from the guide like this is the > > requirement for systemd-boot, the actual Boot Loader Specification > > page appears to suggest that an XBOOTLDR partition is optional. So > > there may be a viable configuration without it. > > No, you do not need an XBOOTLDR partition with systemd-boot and in fact I > have never used one, and I'm not sure why the guide advertises it so > prominently. > > There seems to be a lot of cargo cult around boot partitions (probably left > over from the BIOS days), you really only need the ESP. The set up I have > used for years is ESP at /boot, containing systemd-boot, kernel, initramfs > and so on, and that's it (excluding of course / and other actual system > partitions). > > -Marco
The UAPI Group Boot Loader Specification is trying to square the circle of multiple OSs overwriting each other's kernel images, boot loaders, menu entries, etc. and also to automate the creation and maintenance of such elements by distros. The XBOOTLDR partition is indeed optional and it depends on what type of kernel images you use (Type #1 or #2 as they call it). In addition, the specification explains XBOOTLDR *should*, rather than must, be formatted with a FAT32 fs. It states the XBOOTLDR partition "... should be a file system readable by the firmware". However, if the boot loader's xxxx.efi executable found in ESP is capable of accessing other filesystems with its own drivers, as indeed GRUB is, then I think the XBOOTLDR partition can be formatted with ext* instead. Reading this Boot Loader specification makes me smile at the manual simplicity of using efibootmgr and xxx.efi kernel images with no 3rd party bootloaders. :-)
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