re: [Qemu-devel] Host API escape

[EricNorthup]

On Mon, 13 Sep 2004 23:45:07 +0100, Derek Fawcus wrote:

>On Mon, Sep 13, 2004 at 11:16:14PM +0200, Fabrice Bellard wrote:
>> Derek Fawcus wrote:
>> > I was adding a fake instruction
>
>So will you at all interested in this bit,  want to wait for it to
>cook some more first,  or not interested?
>
>It's basically a "new" instruction,  using opcodes that should normally
>generate undefined/illegal opcode traps,  hence it should still be
>usable
>(in some form) if/when doing fast/native x86-on-x86.  The point
> being to provide a a controlled escape to talk with the host -
therefore it's
> called "hostapi"...
[. . .]

Ok, I think the things you can achieve with this mechanism are very
exciting.  But please, *please* do not make another fork in x86!

What if you use the WRMSR instructions instead?  Then you can define
MSRs which have certain behavior when written to / read from.  The whole
point of MSRs is that they are model-specific, and that is the way to do
this compatibly.

Just a suggestion

--Eric