Hi,

I try to add meta-java to example build image.

My build-host is Ubuntu 16.04 LTS. I prepared it according to the book. I'm able to build IOT sample image.

Now, trying to add meta-java layer:

Checked-out meta-iot2000, swtiched to branch V2.2.0.

Modified kas.yml, adding:

meta-java:
   url: git://git.yoctoproject.org/meta-java
   refspec: morty

 Used "morty" refspec as this seems suitable for Yocto 2.2.

Then, during the build, I get error during configure-step for "classpath". The root-cause seems to be segmentation fault of ecj-initial invocation:

configure:25312: /home/xadmin/proj/meta-iot2000/build/tmp/sysroots/x86_64-linux/usr/bin/ecj-initial -nowarn -source 1.5 -target 1.5 Object.java
Segmentation fault (core dumped)
Segmentation fault (core dumped)
....

This looks pretty simlar to issue described here: https://github.com/woglinde/meta-java/issues/49.

But the issue is pretty old and pretty closed, and mentioned patches seems to be applied in meta-java package.

The build process proceeds after this error anyway, but finally fails it bunch of other errors. I think, I'd better fix first error encountered...

My question: did anybody suceeded to add meta-java to this image? If so, please share your build-environment details.

Here is my. modified, iot2000-example-image.inc, which struggles to add meta-java:

WKS_FILE = "example-image.${MACHINE}.wks"

DESCRIPTION = "Example image for the IOT2000 platform"

#example features
IMAGE_FEATURES += " package-management"
IMAGE_FEATURES += " dev-pkgs"
IMAGE_INSTALL_append = " opkg"
IMAGE_INSTALL_append = " imageversionfile"
IMAGE_INSTALL_append = " modules-load-entries"
IMAGE_INSTALL_append = " dmidecode"
IMAGE_INSTALL_append = " openssh"
IMAGE_INSTALL_append = " screen minicom"
IMAGE_INSTALL_append = " mraa upm"
IMAGE_INSTALL_append  = " parted e2fsprogs dosfstools"
IMAGE_INSTALL_append = " curl"
IMAGE_INSTALL_append = " pciutils"
IMAGE_INSTALL_append = " iptables"
IMAGE_INSTALL_append = " cmake"
IMAGE_INSTALL_append = " iw wpa-supplicant wireless-tools"
IMAGE_INSTALL_append = " galileo-target"
IMAGE_INSTALL_append = " iot2000setup"
IMAGE_INSTALL_append = " sqlite3"
IMAGE_INSTALL_append = " i2c-tools"
IMAGE_INSTALL_append = " linux-firmware-common"
IMAGE_INSTALL_append = " python3-pip python3-modules"
IMAGE_INSTALL_append = " setledcolor"
IMAGE_INSTALL_append = " tzcode tzdata tzdata-misc tzdata-posix tzdata-right"
IMAGE_INSTALL_append = " tzdata-africa tzdata-americas tzdata-antarctica"
IMAGE_INSTALL_append = " tzdata-arctic tzdata-asia tzdata-atlantic"
IMAGE_INSTALL_append = " tzdata-australia tzdata-europe tzdata-pacific"
IMAGE_INSTALL_append = " cronie"
IMAGE_INSTALL_append = " openjdk-8"

PREFERRED_PROVIDER_virtual/java-initial = "javavm-initial"
PREFERRED_PROVIDER_virtual/java-native = "javavm-native"
PREFERRED_PROVIDER_virtual/java-initial-native = "javavm-initial-native"
PREFERRED_PROVIDER_virtual/javac-native = "openjdk-javac-native"
PREFERRED_PROVIDER_classpath = "classpath-minimal"
PREFERRED_PROVIDER_openjdk-8-jre = "openjdk-8-jre"

PREFERRED_VERSION_jamvm-initial = "1.4.5"
PREFERRED_VERSION_classpath-initial = "0.93"
PREFERRED_VERSION_jamvm-native = "1.5.3"
PREFERRED_VERSION_classpath-native = "0.99"

PREFERRED_VERSION_jamvm = "1.5.2"
PREFERRED_VERSION_classpath = "0.98"

 Thanks in advance!

A long time ago, we had the openjdk in one of our yocto layers for an ARM device. I remember lots of build breakages, including such segfaults, and I recall some tunings we made back then:

PREFERRED_PROVIDER_virtual/java-initial-native = "cacao-initial-native"
PREFERRED_PROVIDER_virtual/java-initial = "cacao-initial"
PREFERRED_PROVIDER_virtual/java-native = "cacao-native"

Maybe that helps here as well.

Thanks for response,

I tried your suggestions for using cacao instead of javavm - did not help so far, but I must give it a try with fresh repository. This will take a while...

I think about alternative solution: get java JRE as a tar-ball and create own meta-package which will  just install it from supplied tarball instead of building from sources. Should work, huh? As building from sources seems painful at best and impossible at worst...

Your hint about cacao proved working - thanks again.

For those who may try it, these are my java-related settings form iot2000-example-image.inc that worked for me:

IMAGE_INSTALL_append = " openjre-8"
PREFERRED_PROVIDER_virtual/java-initial = "cacao-initial"
PREFERRED_VERSION_cacao-initial = "0.98"
PREFERRED_PROVIDER_virtual/java-native = "cacao-native"
PREFERRED_VERSION_cacao-initial = "0.98"
PREFERRED_VERSION_classpath-initial = "0.93"
PREFERRED_VERSION_cacao-native = "0.99.3"
PREFERRED_VERSION_classpath-native = "0.97.2"
PREFERRED_VERSION_cacao = "0.99.4"
PREFERRED_VERSION_classpath = "0.98"
PREFERRED_PROVIDER_virtual/java-initial-native = "cacao-initial-native"
PREFERRED_PROVIDER_openjdk-8-jre = "openjdk-8-jre"

There were several warnings during build like:

WARNING: /home/xadmin/proj/meta-iot2000/meta-java/recipes-core/openjdk/openjdk-8-native_102b14.bb: Unable to export ${CXXFLAGS}: Failure expanding variable CXXFLAGS, expression was -isystem/home/xadmin/proj/meta-iot2000/build/tmp/sysroots/x86_64-linux/usr/include -O2 -pipe -D_GLIBCXX_USE_CXX11_ABI=0 ${@version_specific_cflags(d)} ${@jdk_cpp_options(d)} which triggered exception IndexError: string index out of range

 
but the process completes producing the image with Java 8 installed and operational.

I can confirm by using the PREFERRED_PROVIDER setting you identified (thanks for that) meta-java scarthgap branch's openjdk-8-native is built , installed and operational.

I have troubles confirming it is java 1.8.

After successfully compiling openjdk-8-native /w your settings  I tried to use it to build an application (Actually I used ANT w/ a dedicated plugin to build a Javacard applet), and I added to the do_compile yocto task the request to print the tools version:
do_compile() {
   which ant
   ant -version
   which javac
   javac -version
   which java
   java -version

… other lines adjusting the classpath especially to include tools.jar, and for invoking ANT

The ant execution result in error 

This is the output in the error log that unfortunately seems to describe a java 1.6 installation inconsistently named openjdk-8.

The error reported by javac (UnsupportedClassVersionError 52.0) is also consistent with providing an plugin compiled for java 1.8 to an earlier java version . 

| DEBUG: Executing shell function do_compile
| <omitted local path>/work/armv8a-poky-linux/isoapplet-4096/2.0/recipe-sysroot-native/usr/bin/ant
| Apache Ant version 1.8.1 compiled on Wed, 23 Jul 2025 10:12:44 +0000
| <omitted local path>/work/armv8a-poky-linux/isoapplet-4096/2.0/recipe-sysroot-native/usr/bin/javac
| Eclipse Compiler for Java(TM) 0.A76_R36x, 3.6.2, Copyright IBM Corp 2000, 2010. All rights reserved.
| <omitted local path>/work/armv8a-poky-linux/isoapplet-4096/2.0/recipe-sysroot-native/usr/bin/java
| java version "1.6.0"
| CACAO version 1.6.2pre

java.lang.UnsupportedClassVersionError: com.sun.tools.javac.Main (Unsupported major.minor version 52.0)

Is this different in your build?

Did I wrongly interpret the error or am I doing something else wrong?
Thanks
PC