避免/减少Travis-CI构建的多次安装

Question

For our Travis-CI builds of the Jailhouse hypervisor , we have a rather costly environment setup which consists of a partial distribution update to pull in a recent make version (>=3.82, the default one is still only 3.81 - Ubuntu...), a cross toolchain for ARM and a 100 MB package of prebuilt Linux kernel sources that we need to compile an out-of-tree module.

To reduce the build time and the number of kernel downloads, we currently build all configuration variants sequentially in a single run (make; make clean; make...). That was fine for checking for build breakages, but with the addition of a Coverity scan, which depends on the build outputs, it no longer works. Switching to a build matrix seems the obvious solution, at the price of multiple installations because Travis-CI seems to be unable to reuse them during such builds. While we currently only have 3 configuration variants, this will increase in the future (eg every ARM board added will increase it by one), thus the approach does not really scale.

Do we have any alternatives? I already looked at caching, available via the docker-based build, but lacking sudo support there prevents this approach. Other ideas?

Answer 1

You should change your build to do this

cov-build --idir <target1> make; make clean
...

Use different intermediate directories for each build. Then go back later and run

cov-analyze --idir <target1>
cov-commit-defects --idir <target1> --stream <target1>