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libxl: Fix build with recent Xen that introduces new disk backend type

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.com/
[2] https://lore.kernel.org/xen-devel/E1oHEQO-0008GA-Uo@osstest.test-lab.xenproject.org/

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
Oleksandr Tyshchenko 2022-07-29 18:50:24 +03:00 committed by Michal Privoznik
parent f3ce408b67
commit ce2358d07a
2 changed files with 7 additions and 0 deletions

View File

@ -1240,6 +1240,10 @@ libxlUpdateDiskDef(virDomainDiskDef *l_disk, libxl_device_disk *x_disk)
driver = "phy"; driver = "phy";
break; break;
case LIBXL_DISK_BACKEND_UNKNOWN: case LIBXL_DISK_BACKEND_UNKNOWN:
#ifdef LIBXL_HAVE_DEVICE_DISK_SPECIFICATION
case LIBXL_DISK_BACKEND_STANDALONE:
#endif
default:
break; break;
} }
if (driver) if (driver)

View File

@ -715,6 +715,9 @@ xenParseXLDisk(virConf *conf, virDomainDef *def)
virDomainDiskSetDriver(disk, "phy"); virDomainDiskSetDriver(disk, "phy");
virDomainDiskSetType(disk, VIR_STORAGE_TYPE_BLOCK); virDomainDiskSetType(disk, VIR_STORAGE_TYPE_BLOCK);
break; break;
#ifdef LIBXL_HAVE_DEVICE_DISK_SPECIFICATION
case LIBXL_DISK_BACKEND_STANDALONE:
#endif
default: default:
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
_("disk backend not supported: %s"), _("disk backend not supported: %s"),