When testing the latest master branch, qemu dies with the above error message. The issue seems to have been introduced by the following recent patch:
xen: convert to MemoryListener API (20581d207853fe4b1af88b116f077516dfa888cd) Commenting the assert() prevents qemu from dying, but there may be another underlying problem with framebuffer dirty page tracking because the display is really slow on my setup (It wasn't the last time I tried). -- Julian
