Re: [Qemu-devel] RFC: libyajl for JSON

[Peter Maydell <peter.maydell@linaro.org>]

On 30 October 2015 at 19:45, Eric Blake <eblake@redhat.com> wrote:
> Loaded question in response to
> https://lists.gnu.org/archive/html/qemu-devel/2015-10/msg06988.html, but
> posting as a new thread to call attention to it:
>
> Libvirt uses libyajl to parse and format JSON. Would it be worth
> dragging in yet another prerequisite library into qemu and reuse
> libyajl's parser instead of our own hand-rolled one?
>
> I know that a while ago, the answer was "as long as we support
> out-of-the-box builds on RHEL 5, that platform lacks yajl therefore we
> can't depend on it" (and libvirt's solution on RHEL 5 is "qemu doesn't
> support QMP and thus doesn't use JSON and thus libvirt doesn't need yajl
> there").
>
> But now that we have just recently bumped the minimum glib and python
> versions to something not available on RHEL 5, it may also be time to
> start thinking about outsourcing to libyajl, because as far as I can
> tell, every platform that currently supports qemu out of the box has a
> version of libyajl. And since libvirt has already figured out the grunt
> work of how to simultaneously code to both the 1.x and 2.x APIs, it's
> not that much of a stretch to reuse that work in qemu.

Even my OSX box's fink installation has yajl1 ;-)
OTOH, extra hard dependencies are a bit painful, especially
for people doing cross-compiles. One option would be to have
a git module for people who don't have a system version, as
we do already for pixman and dtc.

thanks
-- PMM