[meta-xilinx] Xilinx QEMU in meta-xilinx

[Nathan Rossi]

On Wed, Jul 20, 2016 at 10:21 AM, Alistair Francis
<alistair.francis at xilinx.com> wrote:
> Hello everyone,
>
> Xilinx maintains it's own version of QEMU based on the mainline
> version of QEMU: https://github.com/xilinx/qemu/
>
> This tree has a lot of focus on extra support and features for the
> Xilinx architectures. Although we are trying to get all of these
> features upstream to mainline QEMU it is slow work and unfortunately
> not always possible.
>
> We are looking at providing support to build the Xilinx QEMU in the
> meta-xilinx layer. This could be disabled by default and enabled by
> changing the PREFERRED_VERSION_qemu variable. The advantage this would
> bring is much more accurate and extensive support for emulating the
> Xilinx platforms.

Hi Alistair,

This sounds like a great feature.

Some things to consider about having two versions of QEMU. Due to how
qemu is built and populated into the native sysroot, only one binary
version can exist at a time and because switching machines does not
change the native sysroot this would cause a rebuild of qemu when
switching from a meta-xilinx machine (set to use the xilinx qemu) to
for example a qemu* machine in oecore.

An alternative that may be worth looking into is to have both version
populated in the sysroot at the same time. This could be done a number
of ways, the easiest would be to install the qemu binaries into a
/usr/bin/qemu-xilinx/ subdir. And have a "qemu-xilinx" recipe that
inherits qemu.inc.

Also I think there would need to be a runqemu script or similar setup
in meta-xilinx to handle the Xilinx QEMU due to some of features that
are not available in mainline (e.g. fdt-generic, loader, etc).

>
> What is the consensus on this, do people think that including the
> Xilinx tree of QEMU is acceptable?

It sounds acceptable to me.

Regards,
Nathan

>
> Thanks,
>
> Alistair