Messages in this thread | | | Date | Wed, 08 Jan 2003 11:48:29 -0800 | From | "H. Peter Anvin" <> | Subject | Re: tenth post about PCI code, need help |
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Richard B. Johnson wrote: > On 8 Jan 2003, H. Peter Anvin wrote: > > >>Followup to: <Pine.LNX.3.95.1030108132812.28791A-100000@chaos.analogic.com> >>By author: "Richard B. Johnson" <root@chaos.analogic.com> >>In newsgroup: linux.dev.kernel >> >>>The problem is that he's discovered something that's not supposed >>>to be in the code. Only 32-bit accesses are supposed to be made to >>>the PCI controller ports. He has discovered that somebody has made >>>some 8-bit accesses that will not become configuration 'transactions' >>>because they are not 32 bits. >>> >> >>Right. That's what the code is checking for. >> >> -hpa > > Somebody is very lucky the designer of the bus interface state-machine > let him get away with it. This is a borderline "insane instruction" that > could, on some (future?) machine, require a power-off to recover. This is > NotGood(tm). It's like testing a fuse by shorting out a circuit. If it > works, the circuit no longer works. If I doesn't, the circuit no longer > works. Some things should not be tested. >
If so, we will get an bug report rather than mysterious strange behaviour. This is a good thing. (Amusingly enough, exactly this code in the Linux kernel actually found a bug in one of the very early versions of the Transmeta northbridge. It was fixed in firmware.)
-hpa
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