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

[Jordan Justen <jljusten@gmail.com>]

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Anthony,

That seems like a reasonable request.

So, a 'info port80' command would be preferable to having i/o port 0x80 be
read/write?

I still think the read/write port route would
* better emulate systems,
* be more flexible (allowing software the option to read it),
* and, be easier to implement :)

But, I think the most important part is to make the data accessible
somehow.  So, the monitor access method would work fine as well.

-Jordan

On Mon, Jun 29, 2009 at 8:31 AM, Anthony Liguori <anthony@codemonkey.ws>wrote:

> 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
>
>

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