ptrdiff
ptrdiff(desc, blob), ptrdiff(cmds, blob), cmds_size,
ptrdiff(desc, blob), ptrdiff(cmds, blob), cmds_size,
desc = base + ptrdiff(ct->ctbs.recv.desc, blob);
cmds = base + ptrdiff(ct->ctbs.recv.cmds, blob);
desc = base + ptrdiff(ct->ctbs.send.desc, blob);
cmds = base + ptrdiff(ct->ctbs.send.cmds, blob);
cmp = ptrdiff(vma->vm, vm);