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]

Message-ID: <47796363.8060604@zytor.com>
Date:	Mon, 31 Dec 2007 13:47:15 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	Ondrej Zary <linux@...nbow-software.org>,
	Rene Herman <rene.herman@...access.nl>,
	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	dpreed@...d.com, Islam Amer <pharon@...il.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

Alan Cox wrote:
>> What about HP PCLan 16/TP+ cards? I have one that runs 24/7 in a 486 box 
>> (2.6.20.6 kernel) and one spare. It has some VLSI HP chip and also ST-NIC 
>> DP83902AV - is that a good candidate for testing?
> 
> What are you trying to test. The documentation explicitly says you need
> the delays and that the delays are in bus clocks not microseconds. That
> means the existing code is correct and it needs a delay dependant on the
> ISA bus clock frequency (somewhere between 6 and 12MHz). Note that the
> delay depends on the bus clock frequency not time.
> 
> We don't do overclocking, we don't support overclocking, please do not
> overclock your ethernet chip.
> 

However, assuming a bus clock of 6 MHz should be safe (167 ns).

4 bus clocks would be 667 ns, or we can round it up to 1 ms to deal with 
bus delay effects.

None of this really helps with *memory-mapped* 8390, though, since 
memory mapped writes can be posted.  Putting any IOIO transaction in the 
middle has the effect of flushing the posting queues; an MMIO read would 
   also work.  The WD80x3 cards were memory-mapped, in particular (and 
were some of the very first cards supported by Linux.)

	-hpa
--
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/