testbios and the system timer

Eric W. Biederman ebiederman at lnxi.com
Tue Jun 8 11:33:01 CEST 2004

Richard Smith <rsmith at bitworks.com> writes:

> Eric W. Biederman wrote:
> >> You can in the emulator redirect I/O port access to a function. Write the
> >> code to handle read/write on those ports and use the emulate_counter to drive
> >> the clock value.
> > Let me ask this quick question.  Does the emulator restrict port I/O to
> > just the resources on a particular VGA device?   If not that is something
> > we need to do to implement to ensure we flush these kinds of issues
> > into the open and ensure the emulator is portable.
> No. It allows full access to all IO ports. Otherwise it would have never been
> able to get to the system timer.

I was afraid of that.

> So not only will it have to emulate x86 instructions it will have to emulate
> some of the generic x86 hardware setup.

Exactly.  But in this case emulation is more predictable than making
certain your hardware is setup in a legacy conforming mode.


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