Re: [libvirt] [PATCH] util: Fix configure.ac check for DEVLINK_CMD_ESWITCH_GET

Rather than checking for whether the devlink.h on the system has multiple symbols, let's only check for whether the command we want is defined. Turns out the mechanism of providing multiple definitions to check via AC_CHECK_DECLS in order to determine whether HAVE_DECL_DEVLINK should be set resulted in a false positive since as long as one of the defs was true, then the HAVE_DECL_DEVLINK got defined. This is further complicated by a change between kernel 4.8 and 4.11 where the originally defined name DEVLINK_CMD_ESWITCH_MODE_GET was changed to DEVLINK_CMD_ESWITCH_GET with the comment/caveat that the old format is obsolete should never be used. Therefore, even though some kernels will have a couple of the same symbols that were added at the same time (DEVLINK_ATTR_ESWITCH_MODE and DEVLINK_ESWITCH_MODE_SWITCHDEV), they won't have the newer name and thus cause a build failure. So even though multiple DEVLINK_CMD_SWITCH* symbols are used to determine whether the set HAVE_DECL_DEVLINK, this should cover those kernels before 4.11 with the old definition. Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; --- I'd push this as a build breaker, but I don't want to need to go through the trouble again if i got this wrong, so hopefully someone who's seeing this can try out the patch... It's also present on a couple of the CI infrastructure environments (f23, centos-7):