Re: [PATCH v2 1/4] um: Add pthread-based helper support

[Benjamin Berg <benjamin@sipsolutions.net>]

On Tue, 2025-03-18 at 22:55 +0800, Tiwei Bie wrote:
> On 2025/3/18 21:16, Johannes Berg wrote:
> > On Tue, 2025-03-18 at 14:06 +0100, Johannes Berg wrote:
> > > On Thu, 2025-03-06 at 23:07 +0800, Tiwei Bie wrote:
> > > > Introduce a new set of utility functions that can be used to create
> > > > pthread-based helpers. Helper threads created in this way will ensure
> > > > thread safety for errno while sharing the same memory space.
> > > 
> > > Using pthreads seemed odd, but Benjamin argues that it's the only way to
> > > get libc to really sort it all out, unless we never use libc syscall
> > > functions, which is probably kind of unreasonable? Or maybe we could?
> > 
> > It's a long list of symbols that are needed:
> > https://p.sipsolutions.net/2f0c8e0de1e69147.txt
> 
> Thanks for the list! That's indeed a long one.

So, if we dropped libc, then I think that would also imply dropping the
abstraction to support hosts other than Linux. And then the hard split
between user/kernel code might not be needed anymore as one would
ideally not rely on system headers at all.

I can imagine that parts of the code base would really benefit (e.g.
include handling). While other parts would obviously become more
complicated (e.g. parsing /proc/cpuinfo, mcontext handling).

It seems to me that the cleanup potential is likely big enough to make
it worthwhile.

Benjamin