Re: [libvirt PATCH] qemu: fix missing error reports in capabilities probing
On 6/15/20 3:56 PM, Daniel P. Berrangé wrote:
The "virsh domcapabilities --arch ppc64" command will fail
with no
error message set if qemu-system-ppc64 is not currently installed.
This is because virQEMUCapsCacheLookup() does not report any error
message if not capabilities can be obtained from the cache. Almost
all methods calling this expected an error to be set on failure.
Once that's fixed though, we see a further bug which is that
virQEMUCapsCacheLookupDefault() is passing a NULL binary path to
virQEMUCapsCacheLookup(), so we need to catch that too.
Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com>
---
src/qemu/qemu_capabilities.c | 11 +++++++++++
src/qemu/qemu_domain.c | 4 +++-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 2dad823a86..97096073e6 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -6068,8 +6068,10 @@ qemuDomainPostParseDataAlloc(const virDomainDef *def,
virQEMUDriverPtr driver = opaque;
if (!(*parseOpaque = virQEMUCapsCacheLookup(driver->qemuCapsCache,
- def->emulator)))
+ def->emulator))) {
+ virResetLastError();
return 1;
+ }
return 0;
}
I think we need to revisit this patch. In my testing, I have qemu built
on a side from git and one domain that runs it. As I updated my system,
but not rebuilt the qemu from git it no longer runs (fails to link):
~/work/qemu/qemu.git/x86_64-softmmu/qemu-system-x86_64: error while
loading shared libraries: libnettle.so.7: cannot open shared object
file: No such file or directory
This is expected. But, virsh start fails with:
error: Failed to start domain fedora
error: An error occurred, but the cause is unknown
I've tracked this down to the virResetLastError() in the hunk above. And
it kind of makes sense - we failed to load capabilities on daemon
startup (oh, yeah, daemon runs from git too, but it's been rebuilt) so
we try again on domain startup. But now that I am reading the commit
message it doesn't make much sense to me either. 'virsh domcapabilities'
has nothing to do with PostParse callbacks, does it? Can it be that this
error reset call is just misplaced?
Michal