.NET Source-build instructions

[lbussell]

There should be easily accessible instructions for building .NET 6.0 from source in the dotnet/installer readme.

The instructions should address everything you need to build .NET from source, including dependencies. Ideally, this would be something we can point Linux distros and package maintainers to for instructions on how to build .NET for their distro.

[omajid]

Hey, @alucryd @loqs @cerebrate @directhex , what documentation would you find helpful?

From my point of view, as a maintain for .NET in Fedora, a doc that covers the following would be useful to have:

• Where can I find the latest releases?
• Where can I find the source code for latest releases?
• How do I build those releases? What dependencies are required?
• Can I bootstrap .NET (so it doesn't download anything at build time but only uses things I have already on disk)? If so, how?
• What architectures can I build .NET on? How do I do that for anything non-x64?
• What are the suggested packages names and their contents? What should the dependencies between packages look like? (Distros are free to deviate, but source-build can make suggestions).

[alucryd]

@omajid That's pretty much what I would ask for, thanks for making this list. Speaking from past experience, compatibility with nspawn and capability needs (if any) would be nice to have as well, this was troublesome in the 2.x era. And the dependency version information as well, minimum and/or maximum version, like how the current dotnet releases don't work with lttng-ust >= 2.13.0.

[sec]

Also what about OS'es that are not supported atm? Like for example, FreeBSD, we're able to crosscompile working SDK, then native build SDK using that as bootstrap - would it be possible to use the same path using source-build? I've tried that, but at some stage it was missing runtime's nupkg specific for FreeBSD - any info how to also include those into tarball for offline build would be nice for ex. :)

[alucryd]

FYI, I tried building 6.0 using the instructions on the installer repository, and it fails during the runtime compilation, the errors seem to stem from error MSB4018: System.MissingMethodException: Method not found: 'Int32 Microsoft.CodeAnalysis.ISymbol.get_MetadataToken()'.

@omajid I see you ran into this before, I'll try disabling package validation like you did.

[alucryd]

Disabling package validation allowed it to progress further, but it still crashed after an hour and a half of compilation... Segfault while building aspnetcore. @omajid can you get past aspnetcore on fedora?

[omajid]

On Fedora 34, the build works end to end. On 35, my builds are hanging (not crashing, just hanging) while trying to build aspnetcore. The actual hang appears to be in the crossgen process.

[alucryd]

Got it. What versions of lttng-ust do you have on 34 vs 35? Wondering if that's the culprit, I'll try to create a lttng-ust2.12 compat package here.

Edit: Nevermind, looked it up on repology. Looks like even using 2.12.2 might not cut it, I'll start with 2.12.0.