Re: [libvirt-users] virDomainMemoryPeek: bad behavior under workload

On Fri, Aug 31, 2012 at 08:09:46AM -0700, Daniel P. Berrange wrote: > On Fri, Aug 31, 2012 at 03:23:18PM +0300, NoxDaFox wrote: >> Here's the typical output: >> >> File "/home/nox/workspace/NOX/src/NOX/hooks.py", line 134, in trigger >> hook.trigger(event) >> File "/home/nox/workspace/NOX/src/NOX/hooks.py", line 33, in trigger >> self.handlers[event]() >> File "/home/nox/workspace/NOX/hooks/volatility.py", line 81, in memory_dump >> for block in Memory(self.ctx): >> File "/home/see/workspace/NOX/src/NOX/lib/libtools.py", line 179, in next >> libvirt.VIR_MEMORY_PHYSICAL) >> File "/usr/lib/python2.7/dist-packages/libvirt.py", line 1759, in memoryPeek >> ret = libvirtmod.virDomainMemoryPeek(self._o, start, size, flags) >> SystemError: error return without exception set > Hmm, that's a peculiar message to see - I can't find anywhere in the > libvirt code that uses that particular messages, so I'm not sure what > has gone wrong here. Oh, I think this might be a python message. Our C binding does LIBVIRT_BEGIN_ALLOW_THREADS; c_retval = virDomainMemoryPeek(domain, start, size, buf, flags); LIBVIRT_END_ALLOW_THREADS; if (c_retval< 0) goto cleanup; py_retval = PyString_FromStringAndSize(buf, size); cleanup: VIR_FREE(buf); return py_retval; } In the 'c_retval< 0' check, I think we should have been doing if (c_retval< 0) { py_retval = VIR_PY_NONE; goto cleanup; } so we actually return Python's idea of None, rather than C's NULL, at which point you'd probably see the real error message from libvirt/QEMU Daniel