6   Limitations

6.1   LEON2 Simics Features

Simics/LEON2 features most of the generic Simics features. There are, however, a number of features not yet supported by Simics/LEON2:
User decoder
It is currently not possible for the user to define or override instructions in Simics/LEON2.
User MMU
It is currently not possible for the user to override the MMU in Simics/LEON2.
Memory hierachy
It is currently not possible to connect a simulated memory hierachy to Simics/LEON2.
The symtable module has not been updated to support the SPARC V8 ABI and is therefore not supported.
Many haps are not implemented. This means that the break-hap command does not work on these haps and that modules cannot depend on these unimplemented haps.

6.2   LEON2 Model Features

Simics/LEON2 implements the devices that are needed to boot and run RTEMS. Some devices functionality may be missing, and some devices are not implemented.
Memory controller registers
The memory controller registers have no effect and neither has the CCR. The write protection registers are unimplemented.
The LEON2 timer implementation utilize lazy evaluation of counter registers, this result in that the counter registers return incorrect values in some cases, e.g. when a timer is disabled the counter register will evaluate to the reload value.

The counters will also differ from real hardware as the LEON2 Simics model is not cycle accurate.

The watchdog timer is unimplemented.
The UARTs do not support timing. They run at infinite speed even if a baud rate is specified.
Parallel I/O
The parallel I/O port is unimplemented.
Secondary Interrupt Controller
The secondary interrupt controller is currently not supported.
OpenCores Ethernet MAC
The OpenCores Ethernet MAC is unimplemented at the moment.