qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] Support for Emulated SMSC 911X


From: Peter Maydell
Subject: Re: [Qemu-devel] Support for Emulated SMSC 911X
Date: Mon, 27 Jan 2014 21:40:00 +0000

On 27 January 2014 21:05, Romanic Dean <address@hidden> wrote:
> Just a small a query here,Can we call different Ethernet Controllers like
> Broadcom or e1000  from VersatilePB board.
>
> Is VersatilePB board only supports SMSC series of controllers?

You need to distinguish:
 * what does the real hardware do?
 * what can you get QEMU to do?
 * what can your guest OS do?

The answer to all of these is different.
(1) Real hardware versatilepb has  the smsc91x, that's what's
physically present on the board. There is also a PCI controller,
so you can use a PCI ethernet card.

Knowing what real hardware does is important because
(a) it's what guest OSes expect
(b) we generally don't accept changes into QEMU which
don't correspond to what the hardware does

(2) QEMU has models of a number of PCI ethernet cards,
which you can use just by saying '-device e1000' or whatever
on the QEMU command line; this will automatically plug the
modelled ethernet card into the modelled PCI bus.

QEMU also has models of some memory-mapped ethernet
controllers (like the 9118 and 91x); you can edit the board
model source to put those anywhere in the memory map you
like, and wire them up to interrupts as you see fit. (I don't
know why you would want to do this, but it is technically
possible.)

For ethernet controllers which QEMU has no model of, you
can't do anything without writing a model of the device first.

(3) Guest OSes will typically only support the devices the
real hardware has, because that's all they are written to
assume. (There is no way to probe for the presence of these
memory mapped devices; the guest must just know they
might exist at specific addresses.) Depending on the OS,
you might be able to modify it or its configuration to make
it work with a different memory map of devices on the board.

thanks
-- PMM



reply via email to

[Prev in Thread] Current Thread [Next in Thread]