On 21.11.2025 22:09, Michael Young wrote:
> The build of xen-4.21.0 with json-c present and yajl not present
> is failing with the error
>
> libxl_nocpuid.c:43:1: error: unknown type name ‘yajl_gen_status’
> 43 | yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
> | ^~~~~~~~~~~~~~~
> libxl_nocpuid.c:43:50: error: unknown type name ‘yajl_gen’
> 43 | yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
> | ^~~~~~~~
> make[6]: ***
> [/builddir/build/BUILD/xen-4.21.0-build/xen-4.21.0/tools/libs/light/../../../tools/Rules.mk:178:
> libxl_nocpuid.o] Error 1
>
> I tested it with the patch below based on libxl_nocpuid.c which did build.
>
> Signed-off-by: Michael Young <[email protected]>
> ---
> tools/libs/light/libxl_nocpuid.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/tools/libs/light/libxl_nocpuid.c
> b/tools/libs/light/libxl_nocpuid.c
> index 0630959e76..71ab49ed61 100644
> --- a/tools/libs/light/libxl_nocpuid.c
> +++ b/tools/libs/light/libxl_nocpuid.c
> @@ -40,11 +40,24 @@ int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t
> domid, bool restore,
> return 0;
> }
>
> +#ifdef HAVE_LIBJSONC
> +#ifndef _hidden
> +#define _hidden
> +#endif
Why would this be needed? libxl_internal provides a definition afaics.
> +_hidden int libxl_cpuid_policy_list_gen_jso(json_object **jso_r,
Nor should the attribute be needed here, as the function declaration ought
to be in scope.
> + libxl_cpuid_policy_list *pcpuid)
> +{
> + return 0;
> +}
> +#endif
> +
> +#if defined(HAVE_LIBYAJL)
> yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
> libxl_cpuid_policy_list *pcpuid)
> {
> return 0;
> }
> +#endif
Maybe unrelated to this build fix, I find it hard to believe that returning
0 (presumably meaning "success") here is appropriate without actually doing
anything. In particular for the new function you add, I think upon success
the caller can expect *jso_r to have got assigned a value. However, without
any commentary it's hard to tell whether there's some "agreement" that the
caller has to pre-set its variable (to, say, NULL).
Also why are the libxl_..._jso() all hidden, while their libxl_..._json()
counterparts aren't? And why would non-exported functions have their
declarations live in a non-private header?
Jan
