[libvirt PATCH v2 0/1] meson: Check header usability
Test pipeline: https://gitlab.com/abologna/libvirt/-/pipelines/850846324 Changes from [v1]: * replace all uses of has_header() with check_header(). [v1] https://listman.redhat.com/archives/libvir-list/2023-April/239672.html Andrea Bolognani (1): meson: Check header usability meson.build | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) -- 2.40.0
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 linux/kmv.h header and consider it to be usable. Later, when an attempt is made to actually include 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 actual usability, as opposed to mere presence, of headers is enough to make things work correctly in all cases. The meson documentation recommends using has_header() instead of check_header() whenever possible for performance reasons, but while testing this change on fairly old and underpowered hardware I haven't been able to measure any meaningful slowdown. https://bugs.debian.org/1024504 Suggested-by: Helmut Grohne <helmut@subdivi.de> Signed-off-by: Andrea Bolognani <abologna@redhat.com> --- meson.build | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/meson.build b/meson.build index d35d5e076b..9a18767fbb 100644 --- a/meson.build +++ b/meson.build @@ -636,14 +636,14 @@ if host_machine.system() == 'freebsd' endif foreach name : headers - if cc.has_header(name) + if cc.check_header(name) conf.set('WITH_@0@'.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') + if not cc.check_header('linux/sockios.h') error('You must install kernel-headers in order to compile libvirt with QEMU or LXC support') endif endif @@ -920,7 +920,7 @@ endif dlopen_use = host_machine.system() != 'windows' dlopen_dep = cc.find_library('dl', required: dlopen_use) if dlopen_dep.found() - if not cc.has_header('dlfcn.h') + if not cc.check_header('dlfcn.h') error('Unable to find dlfcn.h') endif conf.set('WITH_DLFCN_H', 1) @@ -1052,7 +1052,7 @@ if not get_option('nls').disabled() error('gettext() is required to build libvirt') endif - if cc.has_header('libintl.h') + if cc.check_header('libintl.h') conf.set('WITH_LIBINTL_H', 1) elif get_option('nls').enabled() error('libintl.h is required to build libvirt') @@ -1275,7 +1275,7 @@ if wireshark_dep.found() # Wireshark is installing ws_version.h since v2.9.0, but some distributions # are not shipping it. - if cc.has_header('wireshark/ws_version.h') + if cc.check_header('wireshark/ws_version.h') conf.set('WITH_WS_VERSION', 1) endif endif @@ -1470,7 +1470,7 @@ if not get_option('driver_libxl').disabled() and conf.has('WITH_LIBVIRTD') endif # If building with libxl, use the libxl utility header and lib too - if cc.has_header('libxlutil.h') + if cc.check_header('libxlutil.h') conf.set('WITH_LIBXLUTIL_H', 1) endif xl_util_dep = dependency('xlutil') @@ -1755,7 +1755,7 @@ if conf.has('WITH_LIBVIRTD') fs_enable = false endif - if fs_enable and not cc.has_header('mntent.h') + if fs_enable and not cc.check_header('mntent.h') if get_option('storage_fs').enabled() error('<mntent.h> is required for the FS storage driver') else @@ -1962,7 +1962,7 @@ if not get_option('nss').disabled() endif endif - if use_nss and not cc.has_header('nss.h') + if use_nss and not cc.check_header('nss.h') if get_option('nss').enabled() error('Can\'t build nss plugin without nss.h') else -- 2.40.0
On 4/27/23 14:22, Andrea Bolognani wrote:
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 linux/kmv.h header and consider it to be usable. Later, when an attempt is made to actually include 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 actual usability, as opposed to mere presence, of headers is enough to make things work correctly in all cases.
The meson documentation recommends using has_header() instead of check_header() whenever possible for performance reasons, but while testing this change on fairly old and underpowered hardware I haven't been able to measure any meaningful slowdown.
https://bugs.debian.org/1024504
Suggested-by: Helmut Grohne <helmut@subdivi.de> Signed-off-by: Andrea Bolognani <abologna@redhat.com> --- meson.build | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
Reviewed-by: Michal Privoznik <mprivozn@redhat.com> Michal
On Thu, Apr 27, 2023 at 02:57:54PM +0200, Michal Prívozník wrote:
On 4/27/23 14:22, Andrea Bolognani wrote:
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 linux/kmv.h header and consider it to be usable. Later, when an attempt is made to actually include 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 actual usability, as opposed to mere presence, of headers is enough to make things work correctly in all cases.
The meson documentation recommends using has_header() instead of check_header() whenever possible for performance reasons, but while testing this change on fairly old and underpowered hardware I haven't been able to measure any meaningful slowdown.
https://bugs.debian.org/1024504
Suggested-by: Helmut Grohne <helmut@subdivi.de> Signed-off-by: Andrea Bolognani <abologna@redhat.com> --- meson.build | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Thanks! Do you think it's okay for me to push this now, so that it gets included in 9.3.0, or should I rather wait until after the release? -- Andrea Bolognani / Red Hat / Virtualization
On 4/27/23 15:12, Andrea Bolognani wrote:
On Thu, Apr 27, 2023 at 02:57:54PM +0200, Michal Prívozník wrote:
On 4/27/23 14:22, Andrea Bolognani wrote:
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 linux/kmv.h header and consider it to be usable. Later, when an attempt is made to actually include 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 actual usability, as opposed to mere presence, of headers is enough to make things work correctly in all cases.
The meson documentation recommends using has_header() instead of check_header() whenever possible for performance reasons, but while testing this change on fairly old and underpowered hardware I haven't been able to measure any meaningful slowdown.
https://bugs.debian.org/1024504
Suggested-by: Helmut Grohne <helmut@subdivi.de> Signed-off-by: Andrea Bolognani <abologna@redhat.com> --- meson.build | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Thanks!
Do you think it's okay for me to push this now, so that it gets included in 9.3.0, or should I rather wait until after the release?
It's a bug fix and as such can and in fact should be merged. Michal
On Thu, Apr 27, 2023 at 03:23:29PM +0200, Michal Prívozník wrote:
On 4/27/23 15:12, Andrea Bolognani wrote:
Do you think it's okay for me to push this now, so that it gets included in 9.3.0, or should I rather wait until after the release?
It's a bug fix and as such can and in fact should be merged.
Excellent, thanks for confirming! Pushed now :) -- Andrea Bolognani / Red Hat / Virtualization
participants (2)
-
Andrea Bolognani -
Michal Prívozník