On 21/01/2023 at 09:49, Wols Lists wrote:

On 20/01/2023 21:01, Pascal Hambourg wrote:

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On 20/01/2023 at 21:26, Wol wrote:

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I think you've just put your finger on it. Multiple EFI partitions is 
outside the remit of linux

I do not subscribe to this point of view. Distributions used to handle 
multiple boot sectors, why could they not handle multiple EFI 
partitions as well ?

Because that means that distros need to know all about EVERY OTHER 
OPERATING SYSTEM?

Why would the distributions need to know all about every other OS, and 
what do you mean by "all" ?

I don't know who's fault it was, probably Microsoft's, but I gave up 
trying to dual-boot a laptop ...

I blame UEFI firmware vendors first, for improperly implementing the 
UEFI boot specification. Then I blame operating system vendors for not 
natively handling the case of multiple redundant EFI partitions.

Back on topic, if you mean Windows+Linux dual boot, it seems unlikely to 
me that this can be achieved with Linux software RAID, because Windows 
does not support it and Windows software RAID usually works on whole drives.
If you mean Linux dual-boot, you do not need multiple boot loaders, one 
single boot loader can boot all Linux systems.

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At the end of the day, it's down to the user, and if you can shove a 
quick rsync in the initramfs or boot sequence to sync EFIs, then 
that's probably the best place. Then it doesn't get missed ...

No, these are not adequate places. Too early or too late. The right 
place is when anything is written to the EFI partition.

I would agree with you. But that requires EVERY OS on the computer to 
co-operate. I think you are being - shall we say - optimistic?

Fact: Other systems outside of linux meddle with the EFI. Conclusion: 
modifying linux to sync EFI *at the point of modification* is going to 
fail. Badly.

I suspect we are misunderstanding each other about the meaning of "sync 
EFI partitions" and it may be my fault for not being clear enough. 
First, I do not mean to sync the whole EFI partition contents but only 
the part which belongs to the running operating system. This way, 
neither knowledge or cooperation of other operating systems is required.
Second, I do not mean "sync" in the sense of doing what rsync does but 
in the sense of writing the same stuff in all EFI partitions in the 
first place, instead of writing stuff in one "main" EFI partition only 
and sync'ing other EFI partitions at a later time.