On Thursday 21 September 2006 10:01, Lee Cartwright wrote:
> Hi everyone,
> I am looking into user mode linux to help with some testing, however I'm
> not sure if it is capable of doing quite what I need. I have a couple of
> questions that I was hoping you could answer.
> 1) Is it possible for an instance of user mode linux to simulate the use
> of a piece of hardware that is not present on the host Linux machine?
> eg. Run an application in user mode linux that accesses something like a
> DMA controller that is not present in the host. If so what is the best
> way of doing this?
It is possible - the application only talks with a device driver normally
(except X.org), so it is possible to write a "faking" driver in the Linux
kernel (though it ain't necessarily easy - it is kernel code anyway).
There is a project for a fake WiFi interface written like this.
Maybe you can use HPPFS if the interface is only through proc - it exports a
fake /proc controlled by a simpler Perl daemon (about 100-200 lines of code
IIRC) on the host.
> 2) Is it possible for an application running on the host Linux machine
> to communicate with an application running on a user mode linux instance
> using something like a pipe or socket?
You can use a regular network socket - nothing else is currently implemented
(and IMHO extending _local_ communication to two _different_ kernel instances
would not work - what if a process wants to pass an fd, or send a signal to
the other side?)
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade
Chiacchiera con i tuoi amici in tempo reale!