From: Olivier Galibert <galibert@pobox.com>
To: linux-kernel@vger.kernel.org
Subject: Re: VGA PCI IO port reservations
Date: Fri, 17 Nov 2000 20:20:09 -0500 [thread overview]
Message-ID: <20001117202009.B2472@zalem.puupuu.org> (raw)
In-Reply-To: <200011172002.UAA01918@raistlin.arm.linux.org.uk> <Pine.LNX.3.95.1001117150349.23529A-100000@chaos.analogic.com>
In-Reply-To: <Pine.LNX.3.95.1001117150349.23529A-100000@chaos.analogic.com>; from root@chaos.analogic.com on Fri, Nov 17, 2000 at 03:27:28PM -0500
On Fri, Nov 17, 2000 at 03:27:28PM -0500, Richard B. Johnson wrote:
> Then, you read the port as a WORD (16 bits). If nothing responds,
> you get the value of 0xffff. If somebody is responding, you will
> read something if it's enabled for writes by devices (reads by the CPU).
What guarantees you that:
1- No device will respond 0xffff for an address it decodes
2- No device will crap up on you simply because you've read one
particular address
If any of these if true for any device out there (I think I have one
in my computer that does the 1/ part in some cases), your code is
unsafe.
OG.
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next prev parent reply other threads:[~2000-11-18 1:50 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-11-17 16:20 Russell King
2000-11-17 16:36 ` Jeff Garzik
2000-11-17 16:46 ` Russell King
2000-11-17 16:52 ` Jeff Garzik
2000-11-17 16:58 ` Russell King
2000-11-17 17:03 ` Jeff Garzik
2000-11-17 17:11 ` Russell King
2000-11-17 21:43 ` Matthew Kirkwood
2000-11-17 22:02 ` H. Peter Anvin
2000-11-18 17:41 ` About IOs, ISA, PCI, and life (WAS: VGA PCI IO port...) Benjamin Herrenschmidt
2000-11-17 17:13 ` VGA PCI IO port reservations Richard B. Johnson
2000-11-17 17:20 ` Russell King
2000-11-17 17:30 ` Alan Cox
2000-11-17 18:06 ` Richard B. Johnson
2000-11-17 19:52 ` Russell King
2000-11-17 19:59 ` Richard B. Johnson
2000-11-17 20:02 ` Russell King
2000-11-17 20:27 ` Richard B. Johnson
2000-11-18 1:20 ` Olivier Galibert [this message]
2000-11-18 2:10 ` H. Peter Anvin
2000-11-18 17:02 ` Alan Cox
2000-11-27 22:10 ` Kai Henningsen
2000-11-17 21:35 ` Marcus Sundberg
2000-11-17 20:13 ` H. Peter Anvin
2000-11-17 20:31 ` Richard B. Johnson
2000-11-17 16:47 ` Brian Gerst
2000-11-17 16:56 ` Russell King
2000-11-17 17:00 ` Jeff Garzik
2000-11-17 18:29 ` H. Peter Anvin
2000-11-17 18:27 ` H. Peter Anvin
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