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Date: Mon, 29 Jun 2009 10:31:22 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH] Implement PC port80 debug register.
References: <1246262725-23825-1-git-send-email-jljusten@gmail.com>	
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To: Jordan Justen <jljusten@gmail.com>
Cc: Avi Kivity <avi@redhat.com>, qemu-devel@nongnu.org

Jordan Justen wrote:
> Avi,
>
> Well, I am not sure if this it globally the case for PC motherboards, 
> but in my experience, it has been read/write.
>
> At least for a system such as qemu, it make it difficult to use the 
> port80 checkpoint of software without being able to read the last 
> value written.

It seems like the more logical thing to do is to save the port80 write 
and have it obtainable via the monitor.

But really, we have other debug mechanisms for BIOSes (like ports 
50x/40x).  That seems like a better thing to use if you're writing 
custom code for QEMU.

Regards,

Anthony Liguori