Re: [libvirt PATCH] meson: Check usability of linux/kvm.h

This fixes cross-building in some scenarios. Specifically, when building for armv7l on x86_64, has_header() will see the x86_64 version of the header and consider it usable. Later, when an attempt is made to actually use it, the compiler will quickly realize that things can't quite work. The reason why we haven't hit this in our CI is that we only ever install the foreign version of header files. When building the Debian package, however, some of the Debian-specific tooling will bring in the native version of the Linux headers in addition to the foreign one, causing Meson to misreport the header's availability status. Checking for its actual usability, as opposed to mere presence, is enough to make things work correctly in all cases. https://bugs.debian.org/1024504 Suggested-by: Helmut Grohne <helmut(a)subdivi.de&gt; Signed-off-by: Andrea Bolognani <abologna(a)redhat.com&gt; --- meson.build | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/meson.build b/meson.build index d35d5e076b..21a4bd5b37 100644 --- a/meson.build +++ b/meson.build @@ -614,7 +614,6 @@ headers = [ 'asm/hwcap.h', 'ifaddrs.h', 'libtasn1.h', - 'linux/kvm.h', 'mntent.h', 'net/ethernet.h', 'net/if.h', @@ -635,12 +634,24 @@ if host_machine.system() == 'freebsd' headers += 'libutil.h' endif +# headers for which we need to check actual usability. in most +# cases, checking for presence is enough (and it's way faster) +check_headers = [ + 'linux/kvm.h', +] + foreach name : headers if cc.has_header(name) conf.set(&#39;WITH_@0(a)&#39;.format(name.underscorify().to_upper()), 1) endif endforeach +foreach name : check_headers + if cc.check_header(name) + conf.set(&#39;WITH_@0(a)&#39;.format(name.underscorify().to_upper()), 1) + endif +endforeach + # check for kernel header required by src/util/virnetdevbridge.c if host_machine.system() == 'linux' if not cc.has_header('linux/sockios.h')