Hi. As part of my work on qemu I've written a simplistic random instruction sequence generator and test harness. To quote the README:
risu is a tool intended to assist in testing the implementation of models of the ARM architecture such as qemu and valgrind. In particular it restricts itself to considering the parts of the architecture visible from Linux userspace, so it can be used to test programs which only implement userspace, like valgrind and qemu's linux-user mode.
I don't particularly expect this tool to be of much general interest outside people developing either qemu or valgrind or similar models, but I have in any case made it publicly available now:
http://git.linaro.org/gitweb?p=people/pmaydell/risu.git%3Ba=tree
-- PMM