Date: Mon, 8 Oct 2001 23:16:51 -0700 (PDT) From: Matt Dillon <dillon@earth.backplane.com> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: John Baldwin <jhb@FreeBSD.ORG>, cvs-all@FreeBSD.ORG, cvs-committers@FreeBSD.ORG Subject: Re: cvs commit: src/sys/i386/include atomic.h Message-ID: <200110090616.f996GpE10358@earth.backplane.com> References: <66596.1002607759@critter.freebsd.dk>
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:In message <200110090434.f994Yam09790@earth.backplane.com>, Matt Dillon writes:
:> I don't think it's a good idea to expose the atomic_*() ops or any other
:> SMP mechanisms in the kernel to userland.
:
:If we are going to be serious about threads, we need to expose some kind
:of atomic ops to userland.
:
:I can't see why they could not be the same as we use in the kernel...
:
:--
:Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
How platform independant do you want to be? If you want userland
atomic ops, they should be entirely separate from the kernel and
almost certainly use a different API. Frankly I think having userland
atomic ops at all is a terrible idea, especially after all the hell
people doing the alpha and IA64 ports went through (are going through?)
with the current kernel atomic ops.
It is far better to have *high* level userland operations, like userland
mutexes (which BTW should be entirely independant of kernel mutexes),
and not expose low level so-called atomic ops to userland at all.
-Matt
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