Writing Device Drivers

Process Layout for Sun4u Platforms

On Sun4u platforms, there are separate kernel and user contexts. The process layout looks like this:


On this platform, KERNELBASE is set to Ox10000000. USERLIMIT defines the upper limit of the user context; it is set to OxF0000000. Addresses below KERNELBASE probably refer to user addresses, while addresses above USERLIMIT probably refer to kernel addresses.