A “Hello World” class to test the JVM will be:

class HelloWorldJamVM {
	public static void main(String[] args) {
		System.out.println("hello world");
	}
}

saved as HelloWorldJamVM.java. However, executing a “Hello World” requires longer steps than writing that class.

In order for the JamVM 1.5.4 to run on Ubuntu, we need (1) build-essential (certainly so) and (2) GCJ with dependency of (3) zlib1g-dev. It’s all available in the Karmic ARM repo. Another thing that we need is GNU Classpath 0.98.

Following the instruction, as root we can then configure, make, make install, make install-strip sources under jamvm-1.5.4 directory. Continue them with the classpath-0.98 sources by configuring as follow

./configure --disable-gtk-peer --disable-gconf-peer --disable-plugin --disable-Werror

and then make install as usual. The whole compiling will run slow for sure as QEMU emulates ARM far from nearing native processor performance in my case.

We can compile the above “Hello World” using GCJ with the command javac, which is actually linked to /usr/bin/gcj-wrapper-4.4.

javac HelloWorldJamVM.java

A HelloWorldJamVM.class bytecode file will appear and we can run this with JamVM

PATH=$PATH:/usr/local/jamvm/bin 
export PATH
jamvm HelloWorldJamVM

QEMU with Ubuntu ARM Cortex A8 running JamVM embedded JVM

Ready-to-use image for from the old Ubuntu 9.10 Karmic is avalaible as suggested in RootStock Wiki .

To run Ubuntu 10,04 Lucid you can create similar .img filled by RootStock generated root file system as described in this post generating lucid-arm.img. Boot image is obtained from Lucid port page, of which I saved with the name vmlinuz-lucid-current-ports which is actually linux kernel 2.6.32-21. Running QEMU is then:

qemu-system-arm -M versatilepb -cpu cortex-a8 \
  -kernel vmlinuz-lucid-current-ports \
  -hda lucid-arm.img -m 256 -append "root=/dev/sda mem=256M devtmpfs.mount=0 rw"

However, adding -redir tcp:3232::22 isn’t directly working (although telnet is showing both directions are functional). This redirection is working with the Karmic image which gives instant ssh on my host laptop as in:

ssh localhost -oPort=3232 -l ubuntu

Note: successful QEMU machine image probably won’t boot successfully with the real board. I can’t use kernel 2.6.38-10 for Lucid rootfs on QEMU, but successfully boot that on DevKit8500D board.

QEMU console of Ubuntu 10.04 VM

First put the Microchip.TXT (the MIB file) under /usr/share/snmp/mibs to easily exchange OID canonical form and name vice versa while making dummy. In this case I’ve modify the MIB to have some additional object i.e. name:
$ snmptranslate -m +Microchip -On Microchip::name
.1.3.6.1.4.1.17095.1.1
so we can then use this correct OID for our dummy.

How?

1. use SetMIBValue() in r1.pl

   $agent->SetMIBValue( '.1.3.6.1.4.1.17095.1.1', ASN_OCTET_STR, "Microchip");
   $agent->SetMIBValue( '.1.3.6.1.4.1.17095.3.13', ASN_INTEGER, 82);

2. Feed r1.snmp for playing as in

   $agent->ParseDataFile( '/usr/local/etc/snmp-emulator/r1.snmp', 0 )

   with the content of

   .1.3.6.1.4.1.17095.1.1 = STRING: Microchip
   .1.3.6.1.4.1.17095.3.13 = INTEGER: 82

In all above two examples we can only GET for Raddle to return an answer for each OID. GETNEXT as in bulk snmpwalk won’t give output because they are not sequenced.

A sample of sequenced data inside a real snmpwalk dump is:

$ snmpwalk -v 1 -c public -On localhost
 
.1.3.6.1.2.1.1.1.0 = STRING: Linux xp-racy 2.6.38-10-generic #46~lucid1-Ubuntu SMP Wed Jul 6 18:40:11 UTC 2011 i686
.1.3.6.1.2.1.1.2.0 = OID: .1.3.6.1.4.1.8072.3.2.10
.1.3.6.1.2.1.1.3.0 = Timeticks: (496371) 1:22:43.71
.1.3.6.1.2.1.1.4.0 = STRING: Root  (configure /etc/snmp/snmpd.local.conf)
.1.3.6.1.2.1.1.5.0 = STRING:
.1.3.6.1.2.1.1.6.0 = STRING: Unknown (configure /etc/snmp/snmpd.local.conf)
.1.3.6.1.2.1.1.8.0 = Timeticks: (0) 0:00:00.00
.1.3.6.1.2.1.1.9.1.2.1 = OID: .1.3.6.1.6.3.10.3.1.1
.1.3.6.1.2.1.1.9.1.2.2 = OID: .1.3.6.1.6.3.11.3.1.1

thus, we can only

$ snmpget -m +Microchip -v 1 -c public localhost Microchip::control.13
Microchip::control.13 = INTEGER: 82

or from other system with no Microchip MIB use

$ snmpget -v 1 -c public 192.168.40.105 .1.3.6.1.4.1.17095.3.13
SNMPv2-SMI::enterprises.17095.3.13 = INTEGER: 82

The tree below may visually explains sequenced data for GETNEXT where our Microchip is branched at private.enterprises.microchip :

$ snmptranslate -m +Microchip -Tp
 
+--iso(1)
   |
   +--org(3)
      |
      +--dod(6)
         |
         +--internet(1)
            |
            +--directory(1)
            |
            +--mgmt(2)
            |  |
            |  +--mib-2(1)
            |     |
            |     +--system(1)
            |     |  |
...
            +--private(4)
            |  |
...
            |  +--enterprises(1)
            |     |
...
            |     +--microchip(17095)
            |        |
            |        +--product(1)
            |        |  |

How GET and GETNEXT appeared in SNMP can be viewed by running snmpd in debug mode with this options:

$ snmpd -m +Microchip -f -L -V -C -I vacm_vars -c /usr/local/etc/snmp-emulator/r1.conf
NET-SNMP version 5.3.1
Connection from UDP: [127.0.0.1]:32770
Received SNMP packet(s) from UDP: [127.0.0.1]:32770
  GET message
    -- control.13

net-SNMP packages are required for Raddle to work on top of primarily snmpd.

yum install net-snmp net-snmp-utils

Prior to installation some rpm packages must be downloaded separately as my local repo (created from original RHEL CD images) may not contain them. They are installed as follow:

rpm -i perl-Carp-Clan-6.00-1.el4.rf.noarch.rpm
rpm -i perl-Bit-Vector-6.4-2.el5.rf.i386.rpm
rpm -i perl-Crypt-DES-2.05-3.2.el5.rf.i386.rpm
rpm -i perl-Digest-SHA1-2.11-1.el5.rf.i386.rpm
rpm -i perl-Digest-HMAC-1.01-2.2.el5.rf.noarch.rpm
rpm -i perl-Socket6-0.20-1.el5.rf.i386.rpm
rpm -i perl-Net-SNMP-5.2.0-1.2.el5.rf.noarch.rpm
rpm -i perl-Date-Pcalc-1.2-1.2.el5.rf.noarch.rpm
rpm -i perl-Date-Calc-5.4-1.el5.rf.i386.rpm

continued by installing net-snmp-perl from original repo

yum install net-snmp-perl

Uncompressing Raddle and successful make test will mean installation is good and can be finished by make install

cd Net-Raddle-0.08
perl Makefile.PL
make test
make install

Replaying SNMP Packets

The idea is to run snmpd which replays a specific prepared-SNMP-packets instead of our own real time system SNMP data (in this case the condition of RHEL 5.2 host). There are three files to do that, let’s name them r1.*:

1. r1.snmp
   A capture from i.e.
   snmpwalk -v 1 -c <community string> -OneU <device> > r1.snmp
2. r1.conf
snmpd will run this instead of the original OS default:
   snmpd -C -I vacm_vars -c /usr/local/etc/snmp-emulator/r1.conf
3. r1.pl
   the perl script where the most basic is to just replay the above r1.snmp

An official documentation to replay SNMP can be found here. I got hold back when trying to listen from other host, it turns out that I must remove the localhost section in r1.conf which will make it to use standard port 161 as well

# Listen on port 9501
#agentaddress    udp:localhost:9501,tcp:localhost:9501

It is also wise to always cut the r1.snmp first to see if the perl works (test with perl -w /usr/local/etc/snmp-emulator/r1.pl) either with warning or clean, meaning no problem with just some of the OIDs found inside the file.