Re: [OE-core] [PATCH] sstate: Add fallback when hardlink fails

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Wed, 2026-04-15 at 13:52 +0200, Michael Arndt wrote:
> Hello Richard,
> 
> > The challenge is that the sstate directory is shared, so two builds can
> > write to the same file at the same time. Our policy is "first wins" and
> > anything later is just skipped. The code also needs to make sure that
> > if the sstate file is written, the paired signature matches.
> 
> Thanks for taking a look at my change. I guess then there is no simple 
> fix for the problem, because checking if the file exists and replacing 
> it must be a single atomic operation. Without hardlinks that is a problem.
> 
>  > Generic try/except cases are almost always a red flag in general.
> 
> Agreed, that was also the reason why I was surprised that my sstate 
> didn't work. The existing code already swallows the IOException from 
> os.link so you don't see the error about the missing hardlink support.
> 
> I guess I will have to use a different file system, but thanks anyway.

If you can catch a specific exception about it being not supported, we
could at least show that to the user and fail. I noticed there are
other generic try/except blocks in there which could probably be
improved.

This is pretty core/key code which we've had challenges with in the
past though and it does need to work simply/reliably!

Cheers,

Richard