GXemul documentation:        Configuration files

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Configuration files


Configuration file syntax:

Configuration files are simple text files. I don't have time to write down a formal syntax right now, so I hope that conveying the syntax through an example is good enough:

  
!!gxemul     <-- configuration files must start like this
!
!  This is an example configuration file for GXemul.
!  Anything following an exclamation mark (and also the exclamation
!  mark itself) is ignored.
!
!  Each configuration file should contain one emul entry. Almost
!  everything else is optional.

emul(
    name("my test emul")	 !  Optional name of this emulation

    !  This creates a network (ethernet):
    net(
	ipv4net("10.2.0.0")  !  The default is 10.0.0.0/8, but
	ipv4len(16)          !  it can be overridden like this.
    )

    !  This creates a machine:
    machine(
	name("My test machine")

	! serial_nr(123)    ! Useful when emulating multiple machines
	                    ! on multiple hosts, and they need to have
	                    ! unique MAC addresses, etc.

	type("dec")		!  This is actually not optional
	subtype("5000/200")

	cpu(R3000)      !  Normally set implicitly to a reasonable
			!  value, depending on type and subtype

	! ncpus(4)
	! use_random_bootstrap_cpu(yes)

	memory(128)	!  128 MB memory. This overrides
			!  the default amount of memory for
			!  this machine type.

	! random_mem_contents(yes)

	! prom_emulation(no)

	! byte_order(big)    !  Normally set implicitly (because
			     !  of type and subtype, or decided
			     !  from the file loaded with load

	load("netbsd-INSTALL")
	bootname("netbsd")
	bootarg("-a")

	! n_gfx_cards(2)         !  for DECstation dual/tripple-head
	! emulated_hz(10000000)  !  for fixing the emulated clock speed

	! add_x11_display("otherbox:0")  !  for dual/tripple-head etc
	! add_x11_display("thisbox:0")

	{
	    Devices can be added like this:

	    device("8250 addr=0x18000800 addr_mult=4")

	    The name comes first, followed by optional parameters.
	    Remember to use 0x for hexadecimal values.
	}

	! force_netboot(yes)
	! start_paused(yes)

	disk("nbsd.img")
	disk("6c:cdrom.iso")

	use_x11(yes)
	x11_scaledown(2)

	! bintrans(disable)
	! old_bintrans(enable)
	! bintrans_size(24)

	! slow_serial_interrupts_hack_for_linux(yes)

	! debugger_on_badaddr(yes)

	{
	    Long comments spanning multiple lines should be surrounded
	    with tuborg parentheses.

	    {  Long comments can be nested.  }

	}

    )

    !  Multiple machine are allowed.
    machine(
	name("another machine")
	type("hpcmips")
	subtype("be300")

	...
    )
)

Starting the emulator with a configuration file is as simple as 

	$ ./gxemul @myconfig
if myconfig is the name of the configuration file.


A minimal example:

Here is an example of what a minimal configuration file might look like:

  
!!gxemul

emul(
    machine(
        type("dec")
        subtype("3max")
        load("netbsd-pmax-INSTALL-2.0")
    )
)

For some machine types, specifying the subtype might not even be necessary. Also, adding a net is quite useful, especially for netbooting kernels.