From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MLHCy-0005Jl-Vv for qemu-devel@nongnu.org; Mon, 29 Jun 2009 09:47:45 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MLHCu-0005H9-F1 for qemu-devel@nongnu.org; Mon, 29 Jun 2009 09:47:44 -0400 Received: from [199.232.76.173] (port=50643 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MLHCt-0005Gi-Tc for qemu-devel@nongnu.org; Mon, 29 Jun 2009 09:47:40 -0400 Received: from mail-ew0-f211.google.com ([209.85.219.211]:63530) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MLHCt-0006I6-D6 for qemu-devel@nongnu.org; Mon, 29 Jun 2009 09:47:39 -0400 Received: by ewy7 with SMTP id 7so4803483ewy.34 for ; Mon, 29 Jun 2009 06:47:38 -0700 (PDT) Message-ID: <4A48C5F5.6030402@codemonkey.ws> Date: Mon, 29 Jun 2009 08:47:33 -0500 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH] Implement PC port80 debug register. References: <1246262725-23825-1-git-send-email-jljusten@gmail.com> In-Reply-To: <1246262725-23825-1-git-send-email-jljusten@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jordan Justen Cc: qemu-devel@nongnu.org Jordan Justen wrote: > From: jljusten > > In PC systems, the byte I/O port 0x80 is commonly made into a > read/write byte. BIOS and/or system software will often use > it as a simple checkpoint marker. > What software does this? Typically, port80 is used as an IO delay mechanism. I'm not aware of it being used to read/write arbitrary data. Regards, Anthony Liguori