Building the XNU kernel with GitHub Actions

[markus-oberhumer]

Created from issue upx/upx#612

[jreiser]

Successfully building an xnu kernel will be a good beginning... but one important goal is to build a user-mode app that can be debugged in order to trace the execution of do_execve(), in order to discover the actual requirements for successful execution of a upx-compressed executable. So save the pieces (the *.o and *.a) and the sequence of commands (what make invokes).

[markus-oberhumer]

Yes, but first step is to actually build that thing.

[markus-oberhumer]

Actions are up and running: https://github.com/upx/upx-fork-apple-oss-distributions-xnu/actions

@tomnific and all: feedback/patches are highly welcome!

[markus-oberhumer]

Two hours later: https://github.com/upx/upx-fork-apple-oss-distributions-xnu/actions/runs/7014467795

Currently stuck at fatal error: 'TrustCache/API.h' file not found

[markus-oberhumer]

And another missing file: fatal error: 'os/firehose_buffer_private.h' file not found

https://github.com/upx/upx-fork-apple-oss-distributions-xnu/actions/runs/7015323992

(Build log artifact is now available)

[jreiser]

A couple months ago I also saw firehose_buffer_private.h missing. An internet search provided links to 3 candidates from previous Apple open-source releases. I picked one, and continued, hacking onward.

[markus-oberhumer]

Found apple-oss-distributions--libdispatch.git/os/firehose_buffer_private.h. Will try to copy that file.

[markus-oberhumer]

Current status on master branch: https://github.com/upx/upx-fork-apple-oss-distributions-xnu/actions/runs/7021092042

• cannot find #include <TrustCache/API.h>; a Google search for TrustCacheQueryToken_t found nothing, so this is probably not public; how to disable this?

• clang: error: unknown argument: "-mach_msg2"; no idea what this means, but I didn't look too closely

I'm done with this for now; build infrastructure and log file upload is in place, so hopefully somebody else will be able to improve things.

[osalbahr]

Would using https://github.com/blacktop/darwin-xnu-build help?

[markus-oberhumer]

@osalbahr Thanks for that link, looks like they try to solve the same problem.

@jreiser Maybe you want to have a look at https://github.com/blacktop/darwin-xnu-build