K 10 svn:author V 6 andrew K 8 svn:date V 27 2017-09-14T17:29:51.135003Z K 7 svn:log V 484 Add support for handling undefined instructions in userspace and the kernel. We can register callbacks to perform the required operation on the saved registers before returning. This is initially used to work around a bug in old versions of QEMU that trigger such an exception when reading from an ID register when it should load z zero value. I expect this could be used with other exception types, e.g. to emulate special register access from userland. Sponsored by: DARPA, AFRL END