This directory contains the files required to build
the fake PROM image that is currently being used to
boot IA64 kernels running under the SGI Medusa kernel.

The FPROM currently provides the following functions:

	- PAL emulation for all PAL calls we've made so far.
	- SAL emulation for all SAL calls we've made so far.
	- EFI emulation for all EFI calls we've made so far.
	- builds the "ia64_bootparam" structure that is
	  passed to the kernel from SAL. This structure 
	  shows the cpu & memory configurations.
	- supports medusa boottime options for changing
	  the number of cpus present
	- supports medusa boottime options for changing
	  the memory configuration.



At some point, this fake PROM will be replaced by the
real PROM.




To build a fake PROM, cd to this directory & type:

	make

This will (or should) build a fake PROM named "fprom".




Use this fprom image when booting the Medusa simulator. The
control file used to boot Medusa should include the 
following lines:

	load fprom
	load vmlinux
	sr pc 0x100000
	sr g 9 <address of kernel _start function> #(currently 0xe000000000520000)

NOTE: There is a script "runsim" in this directory that can be used to
simplify setting up an environment for running under Medusa.




The following parameters may be passed to the fake PROM to
control the PAL/SAL/EFI parameters passed to the kernel:

	GR[8] = # of cpus
	GR[9] = address of primary entry point into the kernel
	GR[20] = memory configuration for node 0
	GR[21] = memory configuration for node 1
	GR[22] = memory configuration for node 2
	GR[23] = memory configuration for node 3


Registers GR[20] - GR[23] contain information to specify the
amount of memory present on nodes 0-3.

  - if nothing is specified (all registers are 0), the configuration
    defaults to 8 MB on node 0.

  - a mem config entry for node N is passed in GR[20+N]

  - a mem config entry consists of 8 hex digits. Each digit gives the
    amount of physical memory available on the node starting at
    1GB*<dn>, where dn is the digit number. The amount of memory
    is 8MB*2**<d>. (If <d> = 0, the memory size is 0).

    SN1 doesn't support dimms this small but small memory systems 
    boot faster on Medusa.



An example helps a lot. The following specifies that node 0 has
physical memory 0 to 8MB and 1GB to 1GB+32MB, and that node 1 has
64MB starting at address 0 of the node which is 8GB.

      gr[20] = 0x21           # 0 to 8MB, 1GB to 1GB+32MB
      gr[21] = 0x4            # 8GB to 8GB+64MB

