Running Etherboot within Bochs ============================== Michael Brown Based on an idea suggested by H. Peter Anvin . $Id$ Bochs is a program that simulates a complete Intel x86 computer, including hardware. It can be used to test Etherboot. There is a special pseudo NIC ("pnic") implemented in Bochs, with a corresponding driver in Etherboot. (There is also an NE2000 ISA driver in Bochs, but it doesn't seem to quite work.) To get bochs running is fairly simple: 1. Get the bochs source code: cvs -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/bochs login cvs -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/bochs co bochs 2. Configure bochs with pushd bochs ./configure --enable-all-optimisations --enable-pci --enable-pnic --enable-debugger --enable-magic-breakpoints --enable-disasm popd 3. Build bochs: make -C bochs 4. Set up a TAP virtual network device: modprobe tun tunctl -u -t tap0 ifconfig tap0 up 10.254.254.2 netmask 255.255.255.0 5. Add the following fragment to /etc/dhcpd.conf: subnet 10.254.254.0 netmask 255.255.255.252 { range dynamic-bootp 10.254.254.1 10.254.254.1; } You will also need to add in any of your usual declarations for Etherboot, e.g. 'filename "vmlinuz.ltsp";'. Note that this setup assumes that your DHCP server, TFTP server etc. all live on the machine you are using for running Bochs. If not, then you're on your own. 6. Restart dhcpd /etc/init.d/dhcpd restart 7. Build Etherboot images pushd ../../src make bin/pnic.dsk popd 8. Start Bochs ./bochs/bochs -q You should get to the debugger prompt "". Type "c" to start running Bochs. You should see Bochs start up, load up Etherboot and attempt to boot from the network. Serial console ============== You can use the program "serial-console" to obtain a virtual serial console for Etherboot running within Bochs. Simply run "./serial-console" on a spare tty (e.g. a separate xterm window) before starting Bochs, and ensure that you have compiled Etherboot with appropriate settings such as CFLAGS+= -DCONSOLE_DUAL -DCOMCONSOLE=0x3F8 -DCONSPEED=9600 There is a manual page for "serial-console"; use "man ./serial-console.1" to view it. TODO ==== Packet forwarding/masquerading - document what must be set up. Mention possibility of using RFB as the display device - in conjunction with the serial console, gives you a test facility that can be accessed remotely. Mention use of BOCHSBP instruction (xchgw %bx,%bx) to avoid need to calculate breakpoints.