Dynamips 0.2.16 was released over on github

Since there has been an update over on the github project, I thought this was a good time to take my existing port, and basically dump it, and make it integrate a lot better.  So this time I did a lot of #ifdef’ing and the code should still compile on UNIX like systems.

I need to go through all the reboot/reload scenarios an try to either find out why it crashes, or just comment out dangerous paths.

So yes there is a good chance on a reload it’ll crash right now.

I also had issues with the new vty code, so I’m still using the old file from an ancient version of dynamips that I seem to have massaged well enough to behave for a primative console at the command prompt.

I put it on Sourceforge, because I’m rebellious like that.

InfoTaskForce running on PowerPC (Dynamips)



Well considering what a hit it was, the last time I did this, I thought I’d give it another go!

And after a bit of fighting, I got it to run!

Now what were the obstacles?  Well for starters not having a full libc certainly hurts things.  Things like a malloc.  And without getting fancy with the memory map I did the lamest cheat ever, which is a 1MB static array I just handed out with a fake malloc (no free, I didn’t bother to track chunks), and you know it works enough.

Also I need to read files, and I need to look more into the hardware to see how to do that.  There seems to be plenty of hooks for NVRAM, but the ROMMON substitute doesn’t seem to support them.  Also there is no ROMMON hook for reading from the console!  The MIPS cilo is more ROMMON dependent, while the PowerPC c1700 talks to the uart directly so this is a PowerPC thing for right now.

I also learned something exciting about ld, which is how it can absorb binary images into objects, that you can link and access directly into your program!  No more having to convert it to hex, make these insane headders that CPP may or may not bomb over.  No you can make them objects right away!

ppc-elf-ld -r -b binary -o planetfa.o planetfa.dat

In this example I read the file planetfa.dat as BINARY, and encapsulate it in an object file called planetfa.o . It’ll now have a symbol name of _binary_planetfa_dat_start for where the image begins, _binary_planetfa_dat_size will tell me how big it is in memory, and _binary_planetfa_dat_end will mark the end of this ‘file’ in memory.

Now in the old days when it was a file I could access it like this:

fread ((char *)ptr,block_size,(int)num_blocks,game_file);

But that won’t work.  So now instead of calling fopen/fclose (which don’t exist in CILO), I set a counter to what my current offset is, change the ‘fseek’ to just set the global counter to where it should be, and when I fread I just memcpy:


I suppose I could just have wrapped the f* calls into some emulation library but I don’t need to get all that crazy sophisticated.

C:\temp\dynamips>dynamips.exe -P 1700 -X -r 4 ciscoload.bin
Cisco Router Simulation Platform (version 0.2.15-experimental(merge uppc smips)Build-3-x86/MinGW stable)
Copyright (c) 2005-2011 Christophe Fillot.
Build date: Sep 19 2015 19:33:12

Local UUID: 0450c178-6480-11e5-a559-019031cf957a

Pcap version [WinPcap version 4.1.3 (packet.dll version, based on libpcap version 1.0 branch 1_0_rel0b (20091008)]
Unsure if this file (c1700_i0_rommon_vars) needs to be in binary mode
Virtual RAM size set to 4 MB.
IOS image file: ciscoload.bin

ILT: loaded table “mips64j” from cache.
ILT: loaded table “mips64e” from cache.
ILT: loaded table “ppc32j” from cache.
ILT: loaded table “ppc32e” from cache.
CPU0: carved JIT exec zone of 64 Mb into 2048 pages of 32 Kb.
C1700 instance ‘default’ (id 0):
VM Status : 0
RAM size : 4 Mb
NVRAM size : 32 Kb
IOS image : ciscoload.bin

Loading BAT registers
Loading ELF file ‘ciscoload.bin’…
ELF entry point: 0x8000d9c8

C1700 ‘default’: starting simulation (CPU0 IA=0xfff00100), JIT enabled.
ROMMON emulation microcode.

Launching IOS image at 0x8000d9c8…
CiscoLoader (CILO) – Linux bootloader for Cisco Routers
Available RAM: 4096 kB
Available commands:

Enter filename to boot:
malloc 64512 offset is 0 offset is now 64522
malloc 38912 offset is 64522 offset is now 103444
Infocom interactive fiction – a science fiction story
Copyright (c) 1983 by Infocom, Inc. All rights reserved.
PLANETFALL is a trademark of Infocom, Inc.
Release 37 / Serial number 851003

Another routine day of drudgery aboard the Stellar Patrol Ship Feinstein. This
morning’s assignment for a certain lowly Ensign Seventh Class: scrubbing the
filthy metal deck at the port end of Level Nine. With your Patrol-issue
self-contained multi-purpose all-weather scrub brush you shine the floor with a
diligence born of the knowledge that at any moment dreaded Ensign First Class
Blather, the bane of your shipboard existence, could appear.

Deck Nine
This is a featureless corridor similar to every other corridor on the ship. It
curves away to starboard, and a gangway leads up. To port is the entrance to
one of the ship’s primary escape pods. The pod bulkhead is closed.

Deck Nine Score: 0/4451
Infocom interactive fiction – a science fiction story
Copyright (c) 1983 by Infocom, Inc. All rights reserved.
PLANETFALL is a trademark of Infocom, Inc.
Release 37 / Serial number 851003

Deck Nine Score: 0/4451

For anyone crazy enough, you can find my MinGW Dynamips on sourceforge, cross compilers for PowerPC, and the branch of the firmware source that includes InfoTaskForce, and the binary image.

While I don’t want to write an OS for this, it is almost tempting.  Or go the other route, and add in some non router based hardware… Like audio hardware, or a framebuffer.

Does anyone have a 1700 to test to see if any of this works?  Or a 7200?! 😀

Continuing with a PowerPC ELF compiler for Windows

Continuing on from yesterdays adventure I built the PowerPC compiler to support the Cisco 1700 (and maybe the 7200 NPE-G2?).

Much to my surprise, this one works too!

Loading ELF file ‘../ciscoload.bin’…
ELF entry point: 0x8000cba0

C1700 ‘default’: starting simulation (CPU0 IA=0xfff00100), JIT enabled.
ROMMON emulation microcode.

Launching IOS image at 0x8000cba0…
Error: Unable to find any valid flash! Aborting load.


Building this was a lot more fun.  I thought I could sidestep building a Linux to PowerPC ELF cross compiler, but as it turns out, to bootstrap libgcc, you really need a compiler that can do this.  But with the steps basically down, it was trivial to whip up.

Although I did keep on hitting this error with the Win32 tools that “-mstrict-align” is not supported, while trying to build the startup and libgcc sources using the MinGW targeted compiler through wine.  But once I had a native Linux to PowerPC toolchain in place, not only could I build the Windows based compiler, but I can also use the flag -mstrict-align on Windows without it complaining.  So lesson learned, have a cross compiler built to the final target to make life easier when building a Canadian cross.

As always, building the binutils package was a snap, just run:

./configure --host=i686-mingw32 --target=ppc-elf -prefix=/ppc

and I had my assembler/linker/librarian in no time.

Because of the aforementioned -mstrict-align issue, I got more creative with the parameters for GCC.

./configure --target=ppc-elf --prefix=/ppc --disable-nls --disable-werror --disable-libssp --without-headers --disable-threads --build=i486-linux-gnu --host=i686-mingw32

But with the Linux to PowerPC cross compiler in place, I was able to quickly generate a working toolchain.

I copied in CILO, and added in a build batch file to manually build it, and updated the test directory to run it.

So for those who are interested here is my toolchains:

And a mirror on sourceforge of my cross toolchains, PowerPC and MIPS.

As a minor addendum, The 1700 can run stuff that is far more complicated than the MIPS.  I’m not sure why I get so many TLB violations for doing something more complicated but I (poorly) ported aclock to run on the cisco 1700!

Aclock on the cisco 1700 via Dynamips

Aclock on the cisco 1700 via Dynamips

The Dynamips ROMMON emulator doesn’t provide the keyboard input function call so it can’t read from the keyboard.  Also it can’t read the clock so I have it running 250,000 dhrystones between clock ticks.  Although I think that is far too many, maybe 125,000 would be more like it but it runs on the PowerPC.  While on the MIPS I get nothing but this:

*** TLB (Load/Fetch) Exception ***
PC = 0x80008964, Cause = 0x00008008, Status Reg = 0x00408103

Oh well.  Maybe it’s a stack problem I guess I’ll have to break down and do a memory map and write a malloc if I want to go down this road.  Although back in 1999 this would be incredible but today I don’t think anyone would run anything but IOS on their cisco hardware.

Building a MIPS Compiler for Windows on a Linux VM!

I’ve tried to build a cross compiler on MinGW32 before, and despite there being obvious steps on how to do it, I’ve never gotten it to work.  Now I’ve built cross compilers before so it’s not like I don’t have any clue on what I’m doing, but the problem is that Windows isn’t UNIX, and I don’t want to use Cygwin.

So that enters another fun possibility known as the Canadian Cross, which is using a machine in the middle to build a compiler.  As we all know, Linux is great for building and running GNU software, so a Linux machine to build my cross compiler would be the best.  Now the whole point of this is that I wanted to build a MIPS program to run on Dynamips.  And through a LOT of googling, I managed to find this program called CILO the cisco Linux loader.  Now as far as I can tell the people trying to port Linux the the MIPS based cisco routers (3600 and 7200) never succeed, but they did manage to leave this bootloader behind.  And compiling it was very tricky as they gave no hints on what to use.  So with a lot of trial and error I found that binutils 2.18 is the minimal version that will work as the code depends on being able to do register aliasing which isn’t present in previous versions.  Also according to this, they were using gcc 4.1.2 in their Linux port. So with some luck I did mange to get CILO to build with a cross compiler on Linux.  Which was pretty awesome to see Dynamips run a C program!

But that doesn’t help me on the Windows side.

Now the first thing that I’d normally do is install the default MinGW cross tools, but because I need ancient binutils and GCC support as newer versions not only won’t work for what I want, but won’t build older versions I tried to keep things in step.  This meant on Linux I first had to build a Linux to Windows cross compiler using binutils version 2.25.1 and GCC version 4.1.2 . Configuring and building binutils was a snap with:

./configure --target=i686-mingw32 --prefix=/usr/local/mingw32

And configuring and building gcc was also a snap with:

./configure --target=i686-mingw32 --prefix=/usr/local/mingw32 --disable-libssp

I thought I could just use a new mingwrt and w32api but that proved disastrous as the newer libs gave me this fun error on trying to link a Win32 execuatable:

 undefined reference to `___chkstk_ms’

And googling that around the consensus is that your binutils, and gcc is too old, and upgrade, granpa!  But I want old software so I naturally have to just use older versions, and for gcc 4.1.2 I wanted:

  • mingwrt-3.18-mingw32-dev.tar.gz
  • w32api-3.15-1.mingw32-dev.tar.lzma

Now I could build and link and test my Linux to Windows toolchain!

Now for the crazy part.

First I need a binutils, so I configured binutils 2.18 like this:

./configure --host=i686-mingw32 --target=mips-elf --prefix=/mips

And sure enough with a little prodding I had a MIPS assembler/linker/librarian and all that fun stuff!

Next was a little (ok a LOT) more fun which was building gcc.

After about 30 aborted attempts I finally got gcc to build with this:

./configure --target=mips-elf --prefix=/mips --disable-libssp --build=i486-linux-gnu --host=i686-mingw32

The fun part of course is that during the build, gcc will want to run the cross compiler and dump it’s host machine bit types by running ‘xgcc -dumpspecs’.  Well thankfully via wine, Linux can run Win32 execuatables so I saved myself a few minutes by not having to copy over the partial compiler, and run the command, and transfer the results back.

So with a bit more hand holding on the build I finally got it to finish compiling by linking /bin/true to fix-headers .  What a mission.  Now I excitedly transfered my build to my Windows host, and setup some environment variables and built the hello world cisco application, and, it worked! (well crashes the same way as the pre-built one, but it does say:

C7200 ‘default’: starting simulation (CPU0 PC=0xffffffffbfc00000), JIT disabled.
ROMMON emulation microcode.

Launching IOS image at 0x80008000…
Hello World!
Image returned to ROM.
Reset in progress…

Which is pretty cool!

I tried to merge in a make utility but that turned out to be kind of screwed up, so I just copied the cross steps from Linux, and now I can build cilo on Windows!

C7200 ‘default’: starting simulation (CPU0 PC=0xffffffffbfc00000), JIT disabled.
ROMMON emulation microcode.

Launching IOS image at 0x8000d2e4…
Error: Unable to find any valid flash! Aborting load.
Image returned to ROM.
Reset in progress…

It may not look like much, but It is running the program!  Dynamips is missing a bunch of hardware, like flash.  Or I found out the ability to read from the console using the promlib.  But it can print to it at least.

So for those who want to give it a try, here is my MIPS-ELF tool-chain for Win32, that includes the cisco loader!

One million packets served!

one million ICMP packets!

Success rate is 100 percent (1000000/1000000)!

So over in my work on porting Dynamips to MinGW, I’ve created a version of SLiRP that sends and receives data over UDP.  In retrospect, something I should have done a long time ago, as it makes troubleshooting it easier as now if it were to crash it’s a stand alone program, so it won’t crash the emulator.

The good news is that I’ve been able to copy files into the virtual router using HTTP.  I’ve even been able to access my OS/2 machine over FTP and load a file!

R1#copy disk0:
Destination filename [README]?
Loading README !
[OK – 76743/4096 bytes]

76743 bytes copied in 8.740 secs (8781 bytes/sec)

R1#dir disk0:README
Directory of disk0:/README

12 -rw- 76743 Sep 18 2015 09:01:08 +00:00 README

66875392 bytes total (41652224 bytes free)

Which is very cool!

Part of the ‘trick’ is that you should set your time out to be as long as possible to send a million packets.  I just set the maximum values.

line con 0

exec-timeout 35791 23
stopbits 1

line aux 0

stopbits 1

line vty 0 4

exec-timeout 35791 0
timeout login response 300
password cisco


In addition, a 7200 with idle performs MUCH better than a 1700 without idle.  There is something up with ptask, and only dispatching packets every so often.  I’m guessing it’s done that way for a reason.

Also one other cool IOS trick I learned today is that you can redirect to a file resource! Say you want that ‘show tech-support’ as a file on the disk? No problem!

show tech-support | redirect disk0:tech.txt

And of course the newer versions of IOS have a ‘do’ command that you can run from config mode to execute user commands.

R1(config)#do who
Line User Host(s) Idle Location
* 0 con 0 idle 00:00:00
2 vty 0 idle 15:24:11
3 vty 1 idle 14:59:56
4 vty 2 idle 13:43:44
5 vty 3 idle 11:23:44

 Take that Junos!

For anyone interested, the binary is included in the latest binary snapshot, and using it is pretty simple:

slirp_rdr.exe 20001 20000

This will listen on port 20001, and send traffic to on port 20000.  Easy right?

Manually interfacing from the hypervisor can be the ‘fun’ part.  I haven’t tested with any of the tools, as I don’t know if they will let you leave something ‘listening’ that isn’t connected. For my tests I end up building something with their UI, then loading up my hypervisor that logs, and seeing what it is actually doing so I can inject stuff like this:

nio create_udp nio_udp99 20000 20001
ethsw add_nio S1 nio_udp99
ethsw set_access_port S1 nio_udp99 1

This creates a udp nio, and attaches it onto the virtual etherswitch S1, and puts it on VLAN 1.  As you can see it listens on UDP port 20000, which is where slirp_rdr is setup to send it’s data to, and it’ll send to 20001 where slirp_rdr is listening.

I’ve hard coded port 42323 to telnet into  As always SLiRP is hard coded to have the following ip address schema:


Be sure to set your router to for this to work, and add as your default gateway.

The ONLY address that will respond to ping is .  This is just the way SLiRP is.  HTTP and TCP based stuff works best, things like PPTP will not.  It’s really hit and miss, but the cool thing is that it doesn’t require any device drivers, it’s all user mode code!

Dynamips on MinGW

It’s always bugged me that the only way to build Dynamips for Windows was with Cygwin.

Well fear no more, I’ve mashed an old version (I would have tried newer, but of course Cmake fails spectacularly and with zero help as always!) and not only does it compile, but it can boot a 7200 version of IOS.

Dynamips on MinGW

Dynamips on MinGW

JIT is broken.  You have to telnet into the console.  And the console is a little wonkey as I’m sure it’s doing a lot more UNIX translation vs being a Win32 program but it does work enough to login, save the config, and reload.

But it’ll crash on reload.

I’m sure it’s full of bugs actually.


I started with Dynamips 0.2.8-RC7-community and started commenting out stuff to get it to compile.  Luckily I found this ezwinports that includes mairix that includes some memory mapping functions, namely mmap and munmap ported to Win32 in an early glibc port. While I was trying to integrate libuuid, I got this fun error:

mingw “error: conflicting types” “UUID”

MinGW includes UUID support, since it’s a Microsoft thing.  Unfortunately libuuid doesn’t include unique names,  so I had to rename uuid_t to uu_uuid_t

//typedef unsigned char uuid_t[16];
typedef unsigned char uu_uuid_t[16];

in the uuid.h header file, along with all instances in Dynamips.

I also borrowed sendmsg/recvmsg along with the msg structures from VLC.  inetaton.c from WSHelper, and finally telnet.h from NetBSD.

After that it was a matter of making sure Winsock starts up, and fixing some linking breakage.

For those who want to try, the binary package is here.  I’ll have to setup git on this machine and upload all the changes.  It shouldn’t require any DLL’s, although I haven’t looked at the pcap stuff, as I mentioned it’s largely untested, so I have no idea if any of it works other than the telnet console.