Re: [Qemu-devel] [PATCH] Implement PC port80 debug register.

[Anthony Liguori]

Jordan Justen wrote:
> From: jljusten <address@hidden(none)>
>
> 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