Frequently asked questions

How do I disable P2 mirrors?

Often times eclipse.org redirects P2 repository requests to a another P2 mirror repository. This mirror might be broken, unavailable or mirroring might not be desired.

To disable the usage of P2 mirrors and force all downloads to go directly to the specified server specify the following maven command line parameter.

-Dtycho.disableP2Mirrors=true

It is also possible to set this property in a user/global settings.xml file. Here is settings.xml snippet:

<profiles>
   ...
   <profile>
     <id>p2</id>
     <properties>
       <tycho.disableP2Mirrors>true</tycho.disableP2Mirrors>
     </properties>
   </profile>
 </profiles>
 
 <activeProfiles>
   ...
   <activeProfile>p2</activeProfile>
 </activeProfiles>

Whether to use proxy or not is environment-specific configuration and as such does not belong in a pom.xml in the source tree.

Where can I find the Maven generated documentation for the Tycho plug-ins?

The documentation is available at:

https://tycho.eclipseprojects.io/doc/latest/

How do I use a different compiler version

Tycho always ships with latest Eclipse Compiler release by default. If you want you can always use an older (or never) release of Eclipse Compiler with this configuration:

<plugin>
  <groupId>org.eclipse.tycho</groupId>
  <artifactId>tycho-compiler-plugin</artifactId>
  <version>${tycho-version}</version>
  <dependencies>
    <dependency>
      <groupId>org.eclipse.jdt</groupId>
      <artifactId>ecj</artifactId>
      <version><!-- Your version here --></version>
    </dependency>
  </dependencies>
</plugin>

For example you can find all released versions here: https://mvnrepository.com/artifact/org.eclipse.jdt/ecj

Snapshot releases can be found here: https://repo.eclipse.org/content/repositories/eclipse-snapshots/org/eclipse/jdt/ecj

Using javac as compiler

As an alternative you can use javac as the compiler backend with Tycho:

<plugin>
	<groupId>org.eclipse.tycho</groupId>
	<artifactId>tycho-compiler-plugin</artifactId>
	<version>${tycho.version}</version>
	<configuration>
		<compilerId>javac</compilerId>
	</configuration>
</plugin>

How to convert an old-style update site (with a site.xml file) into a p2 update site?

An old-style update site (containing a site.xml file) can be converted into a p2 update site in order to use it in a Tycho build in one of the following ways:

• Mirror (remote or local) old-style update site as p2 update site:

  <build>
      <plugins>
          <plugin>
              <groupId>org.eclipse.tycho.extras</groupId>
              <artifactId>tycho-p2-extras-plugin</artifactId>
  
              <!-- use Tycho 3.0.5, as mirroring of old-style update sites is no longer supported since 4.0.0 -->
              <version>3.0.5</version>
  
              <executions>
                  <execution>
                      <id>mirror-update-sites</id>
                      <phase>process-resources</phase>
                      <goals>
                          <goal>mirror</goal>
                      </goals>
                      <configuration>
  
                          <!-- sources: what to mirror and convert -->
                          <source>
                              <repository>
                                  <url>https://zipeditor.sourceforge.net/update</url>
                              </repository>
                              <!-- more update sites... -->
                          </source>
  
                          <!-- optional: convert only the following install units -->
                          <ius>
                              <iu>
                                  <id>zipeditor.feature.group</id>
                              </iu>
                              <!-- more install units... -->
                          </ius>
  
                          <!-- optional: only latest version -->
                          <latestVersionOnly>true</latestVersionOnly>
  
                          <!-- output directory: target/reopsitory/ (${project.build.directory}/repository)
                               or specify the output directory as follows:
                          <destination>${project.basedir}/out</destination>
                          -->
  
                      </configuration>
                  </execution>
  
              </executions>
          </plugin>
      </plugins>
  </build>

• Convert local old-style update site:

  <build>
      <plugins>
          <plugin>
              <groupId>org.eclipse.tycho.extras</groupId>
              <artifactId>tycho-p2-extras-plugin</artifactId>
              <version>${tycho-version}</version>
              <executions>
                  <execution>
                      <id>generate-full-metadata</id>
                      <phase>compile</phase>
                      <goals>
                          <goal>publish-features-and-bundles</goal>
                      </goals>
                      <configuration>
  
                          <!-- input repository: -->
                          <sourceLocation>${project.basedir}/in</sourceLocation>
  
                          <!-- output repository: target/repository/
                               or specify the output directory as follows: -->
                          <metadataRepositoryLocation>${project.basedir}/out</metadataRepositoryLocation>
                          <artifactRepositoryLocation>${project.basedir}/out</artifactRepositoryLocation>
  
                      </configuration>
                  </execution>
              </executions>
          </plugin>
      </plugins>
  </build>