Messages in this thread | | | Date | Tue, 28 May 2002 17:59:16 -0700 | From | george anzinger <> | Subject | Re: linux-2.5.18: DRM + cmpxchg issues |
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Keith Whitwell wrote: > > Adam, > > I expect the answer is that we need to dig out the old one. > > Previously I don't think the full cmpxchg semantics werere required unless the > box is smp -- there's no case where atomic operations are required for > hardware interaction, for example. ... > > Probably this changed with preempt, though, so we need one even on UP boxes... > I can not think of any reason to need a lock or atomic operation because of preempt. Even the management of the preempt on/off flags at most requires memory barriers, even in SMP boxen. Do you have an example? -- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Real time sched: http://sourceforge.net/projects/rtsched/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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