I''m chasing a console bug in Xen 4.0 that only appears with managed PV domains - and even then only after an initial start-->stop sequence. Legacy PV domain config files generally do not specify a console device explicitly but instead get one via qemu with vfb=[''type=vnc,vncunused=1''] When starting a PV domain, xend will create a console device if one is not specified in the domain''s config. Details of the device are added to the domain''s config and, if the domain is managed, written to xend''s internal "db". All of this occurs after the console details are written to xenstore, so life is good for qemu backend reading xenstore. If the managed domain is subsequently stopped and started again, the console device, now included in the domain''s device refs, is created before console info is written to xenstore. The console backend in qemu fails to read xenstore, causing con_init() to fail. Meanwhile the frontend in domU is waiting for backend and booting does not progress. In pseudo-operations create_domain for each device in device_refs: # no console device in device_refs create_device write_device_info_to_xenstore update_consoles # Console device found in xenstore. If it does not exist in # domain device refs, add it and call DevController.createDevice .. shutdown_domain create_domain for each device in device_refs: # now contains console device create_device # device created before info written to xenstore write_device_info_to_xenstore As a workaround, I''ve patched con_init() in tools/ioemu-dir/hw/xen_console.c to retry xenstore read. I suspect xend could be patched to write required console details to xenstore before creating the console device. But the current behavior in xend has not changed since Xen 3.3, the last version I found that doesn''t exhibit this issue. The console code in qemu did change significantly between 3.3 and 3.4 however. Any comments regarding a fix in xend vs qemu? Perhaps alternate solutions to this race? Also noteworthy is that the issue does not appear when using ''ol xenconsoled, i.e. removing vfb entry in domain config. Regards, Jim _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel