Il mar 21 gen 2020, 15:22 Markus Armbruster <arm...@redhat.com> ha scritto:
> > To see it a different way, these are the "C bindings" to QMP, just that > > the implementation is an in-process call rather than RPC. If the QAPI > > code generator was also able to generate Python bindings and the like, > > they would have to be the same for all QEMU binaries, wouldn't they? > > Ommitting the kind of #if we've been discussing is relatively harmless > but what about this one, in qapi-types-block-core.h: > > typedef enum BlockdevDriver { > BLOCKDEV_DRIVER_BLKDEBUG, > [...] > #if defined(CONFIG_REPLICATION) > BLOCKDEV_DRIVER_REPLICATION, > #endif /* defined(CONFIG_REPLICATION) */ > [...] > BLOCKDEV_DRIVER__MAX, > } BlockdevDriver; > Well, I don't think this should be conditional at all. Introspection is a tool to detect unsupported features, not working features. KVM will be present in introspection data even if /dev/kvm doesn't exist on your machine or you don't have permission to access it. I would restrict very much #if usage in QAPI to the very minimum necessary. Paolo > If I omit it in the header, I then have to omit it in > qapi-types-block-core.c's > > const QEnumLookup BlockdevDriver_lookup = { > .array = (const char *const[]) { > [BLOCKDEV_DRIVER_BLKDEBUG] = "blkdebug", > [...] > #if defined(CONFIG_REPLICATION) > [BLOCKDEV_DRIVER_REPLICATION] = "replication", > #endif /* defined(CONFIG_REPLICATION) */ > [...] > }, > .size = BLOCKDEV_DRIVER__MAX > }; > > and God knows what else. But I must not omit it in qapi-introspect.c's > > QLIT_QDICT(((QLitDictEntry[]) { > { "meta-type", QLIT_QSTR("enum"), }, > { "name", QLIT_QSTR("245"), }, > { "values", QLIT_QLIST(((QLitObject[]) { > QLIT_QSTR("blkdebug"), > [...] > #if defined(CONFIG_REPLICATION) > QLIT_QSTR("replication"), > #endif /* defined(CONFIG_REPLICATION) */ > [...] > {} > })), }, > {} > })), > > because that would defeat introspection. > > I smell a swamp. > > I'd rather not complicate the generator to support not including a > header I feel we *should* include. #ifdef CONFIG_FOO can occur not just > in QAPI-generated code, and neglecting to include the relevant header > can cause *nasty* problems not just in QAPI-generated code. Like > inconsistent struct definitions in separate compilation units. Been > there, debugged that, wasn't fun, do not want to go there again. > >