Marc-André Lureau <marcandre.lur...@gmail.com> writes: > Hi > > On Thu, Aug 11, 2022 at 10:52 AM Markus Armbruster <arm...@redhat.com> > wrote: > >> Marc-André Lureau <marcandre.lur...@gmail.com> writes: >> >> > Hi >> > >> > On Fri, Aug 5, 2022 at 12:12 PM Markus Armbruster <arm...@redhat.com> >> wrote: >> > >> >> marcandre.lur...@redhat.com writes: >> >> >> >> > From: Marc-André Lureau <marcandre.lur...@redhat.com> >> >> > >> >> > This is just moving qapi-gen.py and related subdir to qemu-common, to >> >> > ease review and proceed step by step. The following patches will move >> >> > related necessary code, tests etc. >> >> > >> >> > Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com> >> >> >> >> As moved files tend to become low-level annoyances for a long time, I'd >> >> like to understand why you want to move them. The commit message says >> >> "to ease review", which I suspect isn't the real reason. Perhaps you >> >> explained all that elsewhere already, but I missed it. >> >> >> >> >> >> >> > The end goal is to split some projects, such as qemu-ga, to standalone >> > meson projects/subprojects. We will be able to build them independently >> > from the rest of QEMU, and later on perhaps handle them outside of QEMU >> > main repository. To achieve this, I first introduce a qemu-common >> > subproject, where qapi and common units are provided. You can check >> > https://gitlab.com/marcandre.lureau/qemu/-/commits/qga for a sneak peek at >> > current end result. >> >> I worry this move of the QAPI generator code into >> subjprojects/common/scripts/qapi/ will be followed by a move into its >> own subproject. >> > > Do you mean: it could be moved again to another smaller subproject? not > really, see below > > >> Ignorant question: could we turn the QAPI generator into a subproject in >> place? >> > > If it's just the generator, probably the target would then be a python > project (not meson), similar to python-qemu-qmp. > > But I don't see much point, since it's not really a standalone python > module, it generates code, and that code needs most of what is in > qemu-common (see > https://gitlab.com/marcandre.lureau/qemu/-/tree/qga/subprojects/qemu-common). > It's best to have it together imho. Maybe we can consider a different > naming or to be more careful not to add stuff that is not strictly needed > by qapi?
I had a look at subjprojects/qemu-common in your qga branch. Contents: * Subproject machinery * Some common headers (glib-compat.h), but not others (qemu/osdep.h). I guess it's whatever subjproject code needs. Is subprojects/qemu-common/include/block/nvme.h there by accident? * Most of the QObject subsystem qobject/block-qdict.c is left behind. * Most of the QAPI subsystem Some visitors left behind: opts, forward, string input / output. Hmm, only the .c, the .h are in the subjproject. Accident? A bit of HMP support left behind. * Parts of util/ and include/qemu/ Error reporting, key-value CLI, some C utilities, but not others (e.g. qemu/atomic.h, but not qemu/atomic128.h). I guess it's again whatever subjproject code needs. * Parts of the QAPI Schema subsystem Aside: MAINTAINERS mostly not updated. Your moves tear closely related code apart. This is going to be a drag for developers in general and maintainers in particular. Ergonomics suffer when related code is in multiple places. Having to switch between directories and remember where is what will a constant low-level pain. Things that used to be simple & quick, like git-grep qapi/*.c, become more involved. Hurts even when merely consuming the subsystem: when I see #include "qemu/foo.h", the straightforward include/qemu/foo.h may or may not do. When it doesn't, I need to know where to look instead. subprojects/qemu-common/include/ is a lot to type. Sufficiently powerful editors mitigate, but not completely. When changes need to be applied to every instance of an abstraction, it's easy to miss instances "elsewhere". There's a reason the QAPI visitors are all in one place. The actual split seems somewhat arbitrary in places. I suspect more code will move over time. Invalidating "what is where" knowledge. I believe a serious think about other ways to accomplish your goals is called for. > (fwiw, it's a bit of a shame python-qemu-qmp didn't import git history from > qemu.. we did better with libslirp. If we ever move code in standalone > repositories again, we should be careful to keep history with it) Yes, we should preserve history whenever practical. [...]
