Currently, the default jail contents are being built according to a small list of possible systems. These defaults are all hardcoded into framework/c/src/supervisor/app.c. But if Legato is going to be deployable of a wide variety of Linux systems it needs to be more flexible than this. On Debian, for instance, the default libraries come from /lib64, /lib, and /lib/x86_64-linux-gnu. Various distros may have other conventions, and it may be impossible to anticipate them all.
As a starting point for discussion, I’ll make a suggestion.
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Given a target name of
whatever, the build system should look for the environment variableWHATEVER_DEFAULT_IMPORTS. If present, it should be a list of strings: each string is the absolute path of a file to be imported by default into any jail built by that version of Supervisor. -
…something magic happens…
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When building the supervisor application, the explicit jail imports should be detected. The file
app.cshould replace the DefaultSystemLinks array with something along the lines of for each file $F:{.src='$F', .dest='$(dirname $F)/' }This means generating a part of
app.c, and I don’t know how Sierra is going to feel about that. But we’re generating code for components already, so this isn’t a big leap.
Obviously, I’ve skipped something between steps 1 and 3, and that’s what needs to be figured out. Preferably, the same mechanism should be used for the currently supported systems (including the guessed systems), so we avoid a patchwork of defines.
We would still have a framework that worked on a lot of different systems, but could be easily customized for non-standard distros and currently unsupported systems.