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

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Message-ID: <4783B1B2.6070005@reed.com>
Date:	Tue, 08 Jan 2008 12:24:02 -0500
From:	"David P. Reed" <dpreed@...d.com>
To:	Ondrej Zary <linux@...nbow-software.org>
CC:	"H. Peter Anvin" <hpa@...or.com>,
	Rene Herman <rene.herman@...access.nl>,
	Bodo Eggert <7eggert@....de>,
	Christer Weinigel <christer@...nigel.se>,
	Ingo Molnar <mingo@...e.hu>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Paul Rolland <rol@...917.net>, Pavel Machek <pavel@....cz>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	rol@...be.net
Subject: Re: Re: [PATCH] x86: provide a DMI based port 0x80
 I/O delay override.

Windows these days does delays with timing loops or the scheduler.  It 
doesn't use a "port".  Also, Windows XP only supports machines that tend 
not to have timing problems that use delays.  Instead, if a device takes 
a while to respond, it has a "busy bit" in some port or memory slot that 
can be tested.

Almost all of the issues in Linux where _p operations are used are (or 
should be) historical - IMO.

Ondrej Zary wrote:
> On Tuesday 08 January 2008 02:38:15 David P. Reed wrote:
>   
>> H. Peter Anvin wrote:
>>     
>>> And shoot the designer of this particular microcontroller firmware.
>>>       
>> Well, some days I want to shoot the "designer" of the entire Wintel
>> architecture...  it's not exactly "designed" by anybody of course, and
>> today it's created largely by a collection of Taiwanese and Chinese ODM
>> firms, coupled with Microsoft WinHEC and Intel folks.  At least they
>> follow the rules and their ACPI and BIOS code say that they are using
>> port 80 very clearly if you use PnP and ACPI properly.  And in the old
>> days, you were "supposed" to use the system BIOS to talk to things like
>> the PIT that had timing issues, not write your own code.
>>     
>
> Does anyone know what port does Windows use? I'm pretty sure that it isn't 80h 
> as I run Windows 98 often with port 80h debug card inserted. The last POST 
> code set by BIOS usually remains on the display and only changes when BIOS 
> does something like suspend/resume. IIRC, there was a program that was able 
> to display temperature from onboard sensors on the port 80h display that's 
> integrated on some mainboards.
>
>   
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