RE: PCI code: why need outb (0x01, 0xCFB); ?

Nakajima, Jun
2003-01-08T19:53:38Z

Normally all accesses should be long (0xcf8/0xcfc) but x86 is byte addresseable and some chipsets do support byte accesses.

We do not encourage use of byte accesses as it will not be supported in future platforms.

Thanks,
Jun

> -----Original Message-----
> From: H. Peter Anvin [mailto:hpa@zytor.com]
> Sent: Wednesday, January 08, 2003 10:53 AM
> To: linux-kernel@vger.kernel.org
> Subject: Re: PCI code: why need outb (0x01, 0xCFB); ?
>
> Followup to: <F87sTOHYNhMwqvbLaKL0001615a@hotmail.com>
> By author: "fretre lewis" <fretre3618@hotmail.com>
> In newsgroup: linux.dev.kernel
>
> > 1. which device is at port address 0xCFB?
>
> Hopefully none.
>
> > 2. what is meaning of the writing operation "outb (0x01, 0xCFB);" for
> THIS
> > device?, it'seem that PCI spec v2.0 not say anything about it?
>
> It's trying to verify that the PCI northbridge does *NOT* respond to
> this (byte-wide) reference.
>
> -hpa
> --
> <hpa@transmeta.com> at work, <hpa@zytor.com> in private!
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