I have an old HVM guest defined in 3.0.4, and now I'm running 3.1.2 and libvirt 0.4.0. The config looks like this: (domain (image (hvm (vnc 1) (vncdisplay 0) (device (vfb (location localhost:5900) (vncdisplay 0) (uuid ...) The libvirt code looks like this: 1757 /* Graphics device (HVM <= 3.0.4, or PV <= 3.0.3) vnc config */ 1758 if ((hvm && xendConfigVersion < 4) || 1759 (!hvm && xendConfigVersion < 3)) { 1760 tmp = sexpr_fmt_node(root, "domain/image/%s/vnc", hvm ? "hvm" : "linux"); So we don't see the 'vnc 1' at the top. But the code to parse device/vfb doesn't expect this config either: 1685 tmp = sexpr_node(node, "device/vfb/type"); The patch below replaces the later version check with something that copes correctly with the "upgrade" case. regards john 2008-01-15 John Levon <levon(a)movementarian.org&gt; * src/xend_internal.c: fix VNC parsing of old Xen domains on newer Xen versions. diff -prauN libvirt-0.4.0/src/xend_internal.c libvirt-new/src/xend_internal.c --- libvirt-0.4.0/src/xend_internal.c 2007-12-17 15:05:27.000000000 -0800 +++ libvirt-new/src/xend_internal.c 2008-01-14 18:42:08.895060570 -0800 @@ -1371,6 +1371,7 @@ xend_parse_sexp_desc(virConnectPtr conn, unsigned char uuid[VIR_UUID_BUFLEN]; char uuidstr[VIR_UUID_STRING_BUFLEN]; int vif_index = 0; + int found_graphics = 0; if (root == NULL) { /* ERROR */ @@ -1683,6 +1684,7 @@ xend_parse_sexp_desc(virConnectPtr conn, if (tmp && !strcmp(tmp, "sdl")) { virBufferVSprintf(&buf, " <input type='mouse' bus='%s'/>\n", hvm ? "ps2": "xen"); virBufferAdd(&buf, " <graphics type='sdl'/>\n", 27); + found_graphics = 1; } else if (tmp && !strcmp(tmp, "vnc")) { int port = xenStoreDomainGetVNCPort(conn, domid); const char *listenAddr = sexpr_node(node, "device/vfb/vnclisten"); @@ -1700,6 +1702,7 @@ xend_parse_sexp_desc(virConnectPtr conn, if (keymap) virBufferVSprintf(&buf, " keymap='%s'", keymap); virBufferAdd(&buf, "/>\n", 3); + found_graphics = 1; } } } @@ -1751,8 +1754,7 @@ xend_parse_sexp_desc(virConnectPtr conn, } /* Graphics device (HVM <= 3.0.4, or PV <= 3.0.3) vnc config */ - if ((hvm && xendConfigVersion < 4) || - (!hvm && xendConfigVersion < 3)) { + if (!found_graphics) { tmp = sexpr_fmt_node(root, "domain/image/%s/vnc", hvm ? "hvm" : "linux"); if (tmp != NULL) { if (tmp[0] == '1') { @@ -1780,6 +1782,7 @@ xend_parse_sexp_desc(virConnectPtr conn, if (keymap) virBufferVSprintf(&buf, " keymap='%s'", keymap); virBufferAdd(&buf, "/>\n", 3); + found_graphics = 1; } } @@ -1789,6 +1792,7 @@ xend_parse_sexp_desc(virConnectPtr conn, if (tmp[0] == '1') { virBufferVSprintf(&buf, " <input type='mouse' bus='%s'/>\n", hvm ? "ps2" : "xen"); virBufferAdd(&buf, " <graphics type='sdl'/>\n", 27 ); + found_graphics = 1; } } }