On Mi, 10.05.23 17:54, Chris Murphy (lists(a)colorremedies.com) wrote:
On Wed, May 10, 2023, at 5:21 PM, Lennart Poettering wrote:
> So to add to this. I happen to be at LFSMMBPF at the moment, the Linux
> File System summit (among other things) where all the Linux FS people
> meet. I spoke to a couple of FS maintainers here, and well, let me
> make this very clear: using any of the major Linux file systems with
> drivers that are not the ones in the Linux kernel is a very bad idea,
> and expressly not supported by them. [They actually used much harsher
> words, that I'll not repeat here – this is the "friendly" version of
> their take on your idea.]
>
> So, unless you want to go against what the people who actually
> maintain the file systems expressly say please just get this idea out
> of your head that porting Linux file systems into EFI fs drivers was a
> good, supportable idea.
>
> And Neal, Chris, if you don't believe the above, then hey, I am happy
> to open a thread with them in CC where they can tell you in person how
> bad an idea that is.
I don't know what question you asked them. Any modifications
(writes) performed outside kernel code is not supported, since
forever.
No, reading isn't fine either. You might remember the issue with a
sync()ed XFS not being properly readable by grub because linux xfs
semantics meant that sync() returns after data hit the journal but
grub never checked the journal? this mess even intermittendly landed
on my doorstep because people wanted us to freeze/thaw the disk during
shutdown to escape this mess...
The Linux FS people simply dont want to be bound by fucked up
semantics of alternative implementations that do not how to deal with
the situation on disk the same way as Linux.
Hence: get this idea out of your head please. btrfs, xfs, ext4 are not
a sensible option to read from EFI or grub, it's not sustainable.
(Moreover, read-only access doesn't cut it. If you want boot counting
you want write access.)
Read-only drivers, which are the only drivers under discussion here,
aren't a per se problem because they can't modify the file
system. So they have no complaints about that.
No. Not true.
Lennart
--
Lennart Poettering, Berlin