[meta-xilinx] Xilinx QEMU in meta-xilinx

[Alistair Francis]

On Fri, Jul 22, 2016 at 5:45 AM, Nathan Rossi <nathan at nathanrossi.com> wrote:
> 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.

So I have a working solution now, but the problem is that we need our
own qemu.inc and qemu_xilinx.bb.

At the moment I just swap the preferred provider for QEMU to use the
Xilinx one. Do we want to do it this way, or create a new recipe that
builds the Xilinx tree?

I'll look into changing the install location so we can use both, that
is a good idea.

>
> 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).

Yes, it does need a new runqemu/runqemu-internal script. This won't be
automatically sourced from meta-xilinx though, so the user will need
to edit their path to call this one first. Do you know any ways around
that?

>
>>
>> What is the consensus on this, do people think that including the
>> Xilinx tree of QEMU is acceptable?
>
> It sounds acceptable to me.

Awesome!

Thanks,

Alistair

>
> Regards,
> Nathan
>
>>
>> Thanks,
>>
>> Alistair
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