Or1ksim is configured via a configuration file, which is specified by the -f. This is used to specify the detailed behavior of the CPU (virtual memory, caches etc), the various memories to be attached and the behavior of the various peripherals modeled. The structure of the configuration file is described in comments within the default configuration file (sim.cfg supplied in the main directory of Or1ksim).

The Linux distribution, as patched for OpenRISC, is supplied with a configuration file, sim.cfg in its main directory. Three changes are needed to this, for the Linux kernel built in Section 3.4.

	Caution
	Do not attempt to use the sim.cfg supplied with Or1ksim itself. It specifies a completely inappropriate memory configuration for Linux.

Find the line beginning section sim in the file sim.cfg in the main Linux directory. This is followed by lines giving parameter values for the simulation. Linux was built to run at a notional 100MHz. The specification of the time taken by one clock cycle is out by a factor of 1000. Change the value of clkcycle option to 10ns.

Find section uart. This specifies that the channel for I/O should be via TCP port 84. This will probably fail, since the port is in the Well Known Ports range, requiring administrative privileges. If it is desired to run Linux through a telnet link, this should be changed to a value in the Dynamic Range (49152-65535). A separate window can then connect to this port using telnet.

Rather more elegant is to use an xterm for output. For this, change the channel specification to:

channel = "xterm:"
	

Find section ethernet. Linux was built without Ethernet, so this should be disabled. Set the enabled option to 0.