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Followup to: <Pine.LNX.3.95.1020314164142.382B-100000@chaos.analogic.com> By author: "Richard B. Johnson" <root@chaos.analogic.com> In newsgroup: linux.dev.kernel > Well no, IO doesn't "time-out". The PC/AT/ISA bus is asychronous, it's > not clocked. If there's no hardware activity as a result of the write > to nowhere, it's just a no-op. The CPU isn't slowed down at all. It's > just some bits that got flung out on the bus with no feed-back at all. > An OUT on the x86 architecture is synchronous... the CPU will not proceed until the OUT is present on the bus. This is a requirement of the SMM architecture, actually. -hpa -- <hpa@transmeta.com> at work, <hpa@zytor.com> in private! "Unix gives you enough rope to shoot yourself in the foot." http://www.zytor.com/~hpa/puzzle.txt <amsp@zytor.com> - 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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