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/
This archive was generated by hypermail 2b29 : Fri Mar 15 2002 - 22:00:19 EST