Re: Generic way to detect qemu linux-user emulation

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Mar 18, 2025 at 01:34:57PM +0100, Andreas Schwab wrote:
> On Mär 18 2025, Daniel P. Berrangé wrote:
> 
> > Whereever practical, it is preferrable to check a discrete feature
> > or behaviour in a functional way, rather than matching on "is it QEMU"
> 
> Do you know a way to detect support for CLONE_VFORK that isn't too
> expensive?

No, but I feel like the right thing in this particular case is to look
at improving our vfork impl. The current impl is incredibly crude and
acknowledged by the original author

  commit 436d124b7d538b1fd9cf72edf17770664c309856
  Author: Andrzej Zaborowski <balrogg@gmail.com>
  Date:   Sun Sep 21 02:39:45 2008 +0000

    Band-aid vfork() emulation (Kirill Shutemov).

I can see why they did it that way, but I'm feeling like it ought to
be possible to do a better special case vfork impl ni QEMU instead of
overloading the fork() impl.

With regards,
Daniel
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