Comment 17 for bug 1401788

Also note that a bisect result that points to the enabling of a feature is not exhaustative. If you compile the ddx with --enable-userptr you can regression check the ddx over the last couple of years. If you reorder the kernel commits, you can regression check the kernel over the introduction of bdw support. Without taking those steps, it is misleading to point to the feature commit as the *root cause* of the regression.