From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 30 Jan 2001 13:45:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 30 Jan 2001 13:45:37 -0500 Received: from www.topmail.de ([212.255.16.226]:16279 "HELO www.topmail.de") by vger.kernel.org with SMTP id convert rfc822-to-8bit; Tue, 30 Jan 2001 13:45:21 -0500 Message-ID: <00e401c08aec$caae2820$0100a8c0@homeip.net> From: "mirabilos" To: "Linux-Kernel ML" , In-Reply-To: Subject: Re: Linux Post codes during runtime, possibly OT Date: Tue, 30 Jan 2001 18:41:33 -0000 Organization: eccesys.net Linux Distribution Development MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org ----- Original Message ----- From: "Richard B. Johnson" To: "mirabilos" Cc: "Linux-Kernel ML" ; "Mark H. Wood" Sent: Tuesday, January 30, 2001 6:36 PM Subject: Re: Linux Post codes during runtime, possibly OT > On Tue, 30 Jan 2001, mirabilos wrote: > > > [...] > > > > > > > > Now, we've found that small delays are reasonably well generated with > > > > an "outb" to 0x80. So, indeed changing that to something else is going > > > > to be tricky. > > > > > > So how bad would it be to give these people a place to leave the value > > > that they want to have displayed, and have the delay code write *that* > > > instead of garbage? > > > > Because Port &h80 is _not_ decoded by the standard PC hardware. > > There are some ISA and nowadays even PCI cards that convert the value > > OUTted to that port into two 7-segment-digit-LCDisplays, buffered so > > you can read it from the card, but normally no chipset actually > > cares about that port. (I speak of Desktop PCs.) > > > > I repeat: Any OUT to port &h80 is, as long as there are no special > > extensions, just as well as any OUT to port &h1234 or &h4711 or > > whateveryouwant as long as nothing uses it. > > Since Port &h80 is now "reserved" for that POST code usage, > > and it is the safest port one can use in order to delay, > > Linux uses it. > > This is not correct. Port 0x80 is not an "unused" port. It > is decoded by standard hardware: > > C:\>debug > > -i 80 > AE > -o 80 20 > -i 80 > 20 > -q >  > > In this machine I do not have a 'POST-codes' board. Port 0x80 is > an 8-bit read/write latch. It always has been. > > > Cheers, > Dick Johnson OK, I'll check it against every box I've got here. I just was citing what I've learned "ages" ago. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/