Re: [libvirt PATCH] libxl: Fix build with recent Xen that introduces new disk backend type

From: Oleksandr Tyshchenko <oleksandr_tyshchenko(a)epam.com&gt; Xen toolstack has gained basic Virtio support recently which becides adding various virtio related stuff introduces new disk backend type LIBXL_DISK_BACKEND_STANDALONE [1]. Unfortunately, this caused a regression in libvirt build with Xen support enabled, reported by the osstest today [2]: CC libxl/libvirt_driver_libxl_impl_la-xen_xl.lo ../../src/libxl/xen_xl.c: In function 'xenParseXLDisk': ../../src/libxl/xen_xl.c:779:17: error: enumeration value 'LIBXL_DISK_BACKEND_STANDALONE' not handled in switch [-Werror=switch-enum] switch (libxldisk->backend) { ^~~~~~ cc1: all warnings being treated as errors The interesting fact is that switch already has a default branch (which ought to cover such new addition), but the error is triggered as -Wswitch-enum gives a warning about an omitted enumeration code even if there is a default label. Also there is a similar issue in libxlUpdateDiskDef() which I have reproduced after fixing the first one, but it that case the corresponding switch doesn't have a default branch. Fix both issues by inserting required enumeration item to make the compiler happy and adding ifdef guard to be able to build against old Xen libraries as well (without LIBXL_HAVE_DEVICE_DISK_SPECIFICATION). Also add a default branch to switch in libxlUpdateDiskDef(). Please note, that current patch doesn't implement the proper handling of LIBXL_DISK_BACKEND_STANDALONE and friends, it is just intended to fix the regression immediately to unblock the osstest. Also it worth mentioning that current patch won't solve the possible additions in the future. [1] https://lore.kernel.org/xen-devel/20220716163745.28712-1-olekstysh@gmail.... [2] https://lore.kernel.org/xen-devel/E1oHEQO-0008GA-Uo@osstest.test-lab.xenp... Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko(a)epam.com&gt; --- Cc: Julien Grall <julien(a)xen.org&gt; Cc: Anthony PERARD <anthony.perard(a)citrix.com&gt; Cc: Michal Privoznik <mprivozn(a)redhat.com&gt; Please note, the patch is tested on: https://xenbits.xen.org/gitweb/?p=libvirt.git;a=shortlog;h=refs/heads/xen... but should work on the master as well (as the same code is present here). --- src/libxl/libxl_conf.c | 4 ++++ src/libxl/xen_xl.c | 3 +++ 2 files changed, 7 insertions(+)