Re: [Qemu-devel] ISA Proxy - possible?

[amateur <tianlei.zhao@gmail.com>]

On Tue, Jun 19, 2007 at 02:01:50PM +0200, Daniel Schwen wrote:
> Would it be possible to register a set of io ports and io memory locations 
> with qemu and have all read write operations passed on to the host system? 
> 
> A quick look at the source shows me the two look-up tables
> IOPortReadFunc *ioport_read_table[3][MAX_IOPORTS];
> IOPortWriteFunc *ioport_write_table[3][MAX_IOPORTS];
> Instead of the default function (which just generates debug output) it should 
> be possible to register functions which call the ioport read/write commands 
> on the host system (qemu would have to be launched as root to acquire io 
> permissions). 
> 
> Same should work with io memory using the cpu_register_io_memory function.
> Or am I far off base?
> 
> Reason is that I'd like to emulate some very old linux installations which 
> access custom ISA hardware. For some of the ISA boards we have no source 
> code, only binaries linked to a 2.0.something kernel...
-------------------------
I think it is possible just as you said. But, take care of the
interrupts! If your device don't generate interrupts, that's fine! If
they do, then you must find a way to propagate this interrupt signal
to qemu. 

And, there can't be another entity(e.g, host driver) operating on the
device simultaneously.

-- 
You worry too much about your job.  Stop it.  You are not paid enough to worry.