linux-kernel - Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 30 Dec 2007 16:47:49 +0100
From:	Rene Herman <rene.herman@...access.nl>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	dpreed@...d.com, Islam Amer <pharon@...il.com>, hpa@...or.com,
	Pavel Machek <pavel@....cz>, Ingo Molnar <mingo@...hat.com>,
	Andi Kleen <andi@...stfloor.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override

On 30-12-07 16:28, Ingo Molnar wrote:

> Reading from the 0x3cc port does not impact the cursor position update 
> sequence IIRC - i think the vidport is even ignored for the input 
> direction by most hardware, there's a separate input register. The 0x3cc 
> port is a well-defined VGA register which should be unused on non-VGA 
> hardware. (which makes it a perfect delay register in any case)

Hardly. Duron 1300 on AMD756:

rene@...e4:~/src/port80$ su -c ./port80
cycles: out 2400, in 2401
rene@...e4:~/src/port80$ su -c ./port3cc
cycles: out 459, in 394

As stated a few dozen times by now already, port 0x80 is _decidedly_ _non_ 
_random_

Rene.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/