On Wed, May 01, 2024 at 07:27:46PM +0100, Daniel P. Berrangé wrote:
> The various targets which define versioned machine types have
> a bunch of obfuscated macro code for defining unique function
> and variable names using string concatenation.
>
> This addes a couple of helpers to improve the clarity of such
> code macro.
>
> Signed-off-by: Daniel P. Berrangé <berra...@redhat.com>
> ---
> include/hw/boards.h | 166 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 166 insertions(+)
>
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index 2fa800f11a..47ca450fca 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -414,6 +414,172 @@ struct MachineState {
> struct NumaState *numa_state;
> };
>
> +/*
> + * The macros which follow are intended to facilitate the
> + * definition of versioned machine types, using a somewhat
> + * similar pattern across targets:
> + *
> + * #define DEFINE_VIRT_MACHINE_IMPL(latest, ...) \
> + * static void MACHINE_VER_SYM(class_init, virt, __VA_ARGS__)( \
> + * ObjectClass *oc, \
> + * void *data) \
> + * { \
> + * MachineClass *mc = MACHINE_CLASS(oc); \
> + * MACHINE_VER_SYM(options, virt, __VA_ARGS__)(mc); \
Nice to include example usage of the macros. __VA_ARGS__ is getting
expanded quite a few times here, but I don't see that as being too
much of a problem.
> + * // Normal 2 digit eg 'virt-9.0'
> + * #define DEFINE_VIRT_MACHINE(major, minor) \
> + * DEFINE_VIRT_MACHINE_IMPL(false, major, minor)
> + *
> + * // Bugfix 3 digit eg 'virt-9.0.1'
Inconsistent on whether you are using one or two spaces before 'eg'.
> +
> +#define _MACHINE_VER_PICK(x1, x2, x3, x4, x5, x6, ...) x6
This helper macro is powerful; it may be worth a short comment, maybe
along the lines of:
/* Helper macro used to pick the right macro name based on the number
* of extra arguments passed to the containing macro; usage:
*
* _MACHINE_VER_PICK(__VA_ARGS__, \
* MACRO_FOR_5_ARGS, \
* MACRO_FOR_4_ARGS, \
* MACRO_FOR_3_ARGS, \
* MACRO_FOR_2_ARGS)(optional prefix args, __VA_ARGS__)
*/
But once understood, I see it comes in handy in several places below.
Reviewed-by: Eric Blake <ebl...@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc.
Virtualization: qemu.org | libguestfs.org
