From: "Petr Vandrovec" <VANDROVE@vc.cvut.cz>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: PCI code: why need outb (0x01, 0xCFB); ?
Date: Wed, 8 Jan 2003 21:49:39 +0100 [thread overview]
Message-ID: <CACAEBD1F1C@vcnet.vc.cvut.cz> (raw)
On 8 Jan 03 at 10:52, H. Peter Anvin wrote:
>
> > 1. which device is at port address 0xCFB?
>
> Hopefully none.
Actually I'm not sure. This code is here since at least 2.0.28,
and during googling I even found code for direct PCI access
(http://www-user.tu-chemnitz.de/~heha/viewzip.cgi/hs_freeware/gerald.zip/DIRECTNT.CPP?auto=CPP)
which sets lowest bit at 0xCFB to 1 before doing PCI config
accesses and reset it back to original value afterward.
So I believe that there were some chipsets (probably in 486&PCI times)
which did conf1/conf2 accesses depending on value of this bit.
Unfortunately I was not able to confirm this - almost nobody provides
northbridge datasheets from '94 era, even Intel does not provide them
(f.e. Neptune) anymore :-(
Best regards,
Petr Vandrovec
vandrove@vc.cvut.cz
next reply other threads:[~2003-01-08 20:40 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-08 20:49 Petr Vandrovec [this message]
2003-01-08 21:22 ` PCI code: why need outb (0x01, 0xCFB); ? Maciej W. Rozycki
-- strict thread matches above, loose matches on Subject: below --
2003-01-08 21:33 Petr Vandrovec
2003-01-08 21:53 ` Maciej W. Rozycki
2003-01-08 19:10 Nakajima, Jun
2003-01-08 20:40 ` H. Peter Anvin
2003-01-08 21:37 ` Richard B. Johnson
2003-01-07 2:24 fretre lewis
2003-01-06 13:02 fretre lewis
2003-01-06 9:26 fretre lewis
2003-01-06 12:41 ` Gianni Tedesco
2003-01-08 18:52 ` H. Peter Anvin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CACAEBD1F1C@vcnet.vc.cvut.cz \
--to=vandrove@vc.cvut.cz \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.