Make it easier to enable/disable debugging

[MagnusS]

When debugging it would be useful to have a single option for enabling symbols and debugging information and avoid stripping the binary. Now that stacktraces work again it can also be useful with symbols from libcxx and musl. One solution could be to use dontStrip and enableDebugging in nix to control it, see https://nixos.wiki/wiki/Debug_Symbols.

Some debugging options I have found are listed below.

In cmake:

• If you use set(ELF_SYMBOLS true, symbols will be added to the final binary (via https://github.com/includeos/IncludeOS/blob/v0.16.0-release/cmake/os.cmake#L206)
• You can set the library debug option: https://github.com/includeos/IncludeOS/blob/v0.16.0-release/cmake/library.cmake#L44
• There's also CMAKE_BUILD_TYPE=Debug:
  • https://github.com/includeos/IncludeOS/blob/v0.16.0-release/cmake/os.cmake#L93
  • https://github.com/includeos/IncludeOS/blob/v0.16.0-release/cmake/os.cmake#L198)
• ...and a hardcoded NO_DEBUG, which disables the DEBUG-output macro https://github.com/includeos/IncludeOS/blob/v0.16.0-release/cmake/includeos.cmake#L40

Musl and musl-unpatched uses --enable-debug

• https://github.com/includeos/IncludeOS/blob/v0.16.0-release/deps/musl/default.nix#L37
• https://github.com/includeos/IncludeOS/blob/v0.16.0-release/deps/musl-unpatched/default.nix#L20

There could be more :-)

[fwsGonzo]

Everything needs to be built with symbols, and then at the end there's a decision to strip or not. That will also be compatible with backtraces support, since they also need symbols and then strip after.