Running tests under valgrind exposed this: (line numbers are slightly off, due to local changes) ==27876== ERROR SUMMARY: 32 errors from 2 contexts (suppressed: 5 from 2) ==27876== ==27876== 16 errors in context 1 of 2: ==27876== Conditional jump or move depends on uninitialised value(s) ==27876== at 0x41BA18: qemudBuildCommandLine (qemu_conf.c:1871) ==27876== by 0x406764: testCompareXMLToArgvFiles (qemuxml2argvtest.c:46) ==27876== by 0x4069DA: testCompareXMLToArgvHelper (qemuxml2argvtest.c:97) ==27876== by 0x406D60: virtTestRun (testutils.c:69) ==27876== by 0x406A46: main (qemuxml2argvtest.c:114) ==27876== ==27876== 16 errors in context 2 of 2: ==27876== Conditional jump or move depends on uninitialised value(s) ==27876== at 0x41AA45: qemudBuildCommandLine (qemu_conf.c:1606) ==27876== by 0x406764: testCompareXMLToArgvFiles (qemuxml2argvtest.c:46) ==27876== by 0x4069DA: testCompareXMLToArgvHelper (qemuxml2argvtest.c:97) ==27876== by 0x406D60: virtTestRun (testutils.c:69) ==27876== by 0x406A46: main (qemuxml2argvtest.c:114) Both of those are due to uses of uninitialized vm->migrateFrom[0]. Here's the fix: Avoid memory error in a test program. * tests/qemuxml2argvtest.c (testCompareXMLToArgvFiles): Initialize vm.migrateFrom[0], to avoid "read-uninitialized" error from within qemudBuildCommandLine. Index: tests/qemuxml2argvtest.c =================================================================== RCS file: /data/cvs/libvirt/tests/qemuxml2argvtest.c,v retrieving revision 1.5 diff -u -p -r1.5 qemuxml2argvtest.c --- tests/qemuxml2argvtest.c 21 Sep 2007 21:20:32 -0000 1.5 +++ tests/qemuxml2argvtest.c 17 Oct 2007 13:42:15 -0000 @@ -40,6 +40,7 @@ static int testCompareXMLToArgvFiles(con vm.qemuVersion = 0 * 1000 * 100 + (8 * 1000) + 1; vm.qemuCmdFlags = QEMUD_CMD_FLAG_VNC_COLON | QEMUD_CMD_FLAG_NO_REBOOT; + vm.migrateFrom[0] = '\0'; vmdef->vncActivePort = vmdef->vncPort;