[Qemu-devel] Machine config files

[Hollis Blanchard]

On Thu, Nov 13, 2008 at 9:32 PM, Paul Brook <paul at codesourcery.com> wrote:
> It's come up in other contexts recently, so I think it's worth mentioning that
> I am currently working on adding a machine config file support to qemu.
>
> I am focusing on the board setup side of things, rather than the user-level
> config side.  My goal is to come up with a system that will allow e.g. the
> entirety of realview.c and gumstix.c to be eliminated.  Currently this is
> based this round Flattened Device Trees (as used by ppc-linux).
>
> I have looked at the bits that Fabrice did a while ago. While that contains
> some good ideas (which I will probably steal!) it is approaching the problem
> from a somewhat different direction.  FTDs are a much better fit for some of
> my requirements (e.g. being able to pass the config through to the guest OS).
>
> I haven't entirely figured out how this will interact with user config (in
> particular user-pluggable devices like PCI NICs), but I think I can come up
> with something fairly sensible.

Sounds great! For what it's worth, in the PowerPC KVM patches that
I'll be posting here soon, we also use a flat device tree and pass it
to the guest. We start with a template .dtb file in pc-bios/, then
modify things like memory nodes at runtime based on qemu's command
line options.

One practical consideration is that libfdt isn't generally available
as a standalone package. I requested that Debian and Fedora create
packages for it, and they agreed, but those obviously aren't available
in older versions or other Linux distributions.

In the meantime, we could either include a libfdt snapshot in qemu
(which is how it was originally intended to be used), or require users
to build and install the package from source.

-Hollis