Among other disclosed subject matter, a computer-implemented method includes initializing a first descriptor table and a second descriptor table. The first descriptor table is associated with a first permission level and the second descriptor table is associated with a second permission level that is different from the first permission level. The first descriptor table and the second descriptor table are associated with a hardware processor and initialized by an operating system kernel. The method also includes providing a memory address associated with the first descriptor table, in response to a descriptor table address request. The descriptor table address request is provided by a software process. The method also includes updating the second descriptor table, in response to an update request.