Source-build supports ARM64

[dseefeld]

ARM64 is the emerging first architecture to tackle. Fedora and RHEL both have ARM64 as primary architectures:

• Acquire ARM64 hardware
• Build source-build on ARM64 machines
• Add ARM64 machines to an internal agent pool
• Update internal CI to run ARM64 jobs
• Conform to distro build guidelines
  • Build with distro versions of .NET SDK
  • Do native bootstrapping with native ARM64

[omajid]

Just for clarification, is this arm32 or arm64 (aka aarch64)? Or both?

[wfurt]

would there be a reason to do one but not the other? I would think they would be pretty similar.

[deinok]

What is left to be done?

[dagood]

@deinok If you get ZenHub, you should be able to see the issues that are part of this epic, #655 and #699 (as of writing).

[deinok]

@dagood About the Yocto issue, I think that the issue requires this first to be solved.
Yocto is just a toolchain to join multiple packages. The hipotetic meta-dotnet should use source-build to orchestate the compilation of the Yocto layers.
Here you have the meta-mono layer to take it as an example (http://git.yoctoproject.org/cgit/cgit.cgi/meta-mono).

[dagood]

Thanks for the clarification. I think an issue can be in an epic for other reasons than a done dependency--like maybe it still makes sense to track as part of this effort since it's a way to prove out that source-build ARM support is working well enough for people to use. @dseefeld, PTAL, maybe add a done condition to the description?

This epic also isn't broken down yet. I'd expect issues for things like adding ARM CI to be filed once we start working on this.

[deinok]

Just one question @dagood, I feel like there are efforts to have runtime and SDK for x86 and ARM ready for 3.0.0. I'm right?

[tmds]

@dseefeld, does this issue cover building on an arm64 platform. Packaging guidelines may require this.

For example, https://fedoraproject.org/wiki/Architectures:

All builds have to happen in a native environment. this means cross compiling is not allowed, you can however use virtualisation to emulate your target system.

[dleeapho]

I feel like there are efforts to have runtime and SDK for x86 and ARM ready for 3.0.0. I'm right?

@deinok correct. Though ARM64 tarballs are currently available for the Microsoft distribution (ie non-source-built) the overall effort is to round out ARM64 support with packages etc.

Packaging guidelines may require this.
@tmds Thanks for bringing this to our attention. What you say may help to bring up ARM64 priority for source-build.

I'm updating the description with more info. As we get to this work we will be more focused.
/cc @leecow

[omajid]

I was playing around with source-build (master) on arm64, and we use a .NET Core SDK 2.1.403 to build the buildtools. That fails on my arm64 box:

$ /home/omajid/source-build/Tools/dotnetcli/dotnet publish --no-restore /home/omajid/source-build/packages/microsoft.dotnet.buildtools/3.0.0-preview1-03406-03/lib/tool-runtime/project.csproj -f netcoreapp2.0 -o /home/omajid/source-build/Tools
Microsoft (R) Build Engine version 15.8.169+g1ccb72aefa for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

/home/omajid/source-build/Tools/dotnetcli/sdk/2.1.403/Roslyn/Microsoft.CSharp.Core.targets(52,5): error MSB6006: "csc.dll" exited with code 139. [/home/omajid/source-build/packages/microsoft.dotnet.buildtools/3.0.0-preview1-03406-03/lib/tool-runtime/project.csproj]
$ git rev-parse --short HEAD 
f864f9e
$ /home/omajid/source-build/Tools/dotnetcli/dotnet --info
.NET Core SDK (reflecting any global.json):
 Version:   2.1.403
 Commit:    04e15494b6

Runtime Environment:
 OS Name:     rhel
 OS Version:  8
 OS Platform: Linux
 RID:         linux-arm64
 Base Path:   /home/omajid/source-build/Tools/dotnetcli/sdk/2.1.403/

Host (useful for support):
  Version: 2.1.5
  Commit:  290303f510

.NET Core SDKs installed:
  2.1.403 [/home/omajid/source-build/Tools/dotnetcli/sdk]

.NET Core runtimes installed:
  Microsoft.NETCore.App 2.1.5 [/home/omajid/source-build/Tools/dotnetcli/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

Looking around, it looks like 2.x coreclr doesn't actually support arm64 (https://github.com/dotnet/coreclr/issues/19578) ?

[tmds]

arm64 support is for .net core 3.0. This issue tracks that: dotnet/announcements#82