Arm64 support on Linux

[ArielleA]

Arm64 support fixes #1506 requires pull request bazelbuild/bazel#5360

[steeve]

That one looks great, and might even make split configurations work when building ios and android multi arch targets.

[jayconrod]

Change looks good, but it's failing tests. Something about toolchains not being registered. I'll take a look today and figure out what's happening.

[ArielleA]

It's almost certainly because the cpu constraint isn't exported in bazel-tools/platform. That export is in my pull request #5360. Should I withdraw and resubmit once the dependant pull request is complete?

[jayconrod]

Ok, that makes sense.

Let's keep this PR open and wait until bazelbuild/bazel#5360 has been merged and released in a new version of Bazel. At that point, rebase to master and ping me to take another look. I'll update the minimum supported version of Bazel and merge this.

[googlebot]

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[jayconrod]

Bazel 0.15.0 is now released. I'd like to to one more major release of rule_go (likely early next week) before merging this PR and making Bazel 0.15.0 the minimum supported version.

[vielmetti]

The Bazel 0.15.0 release issue is here: bazelbuild/bazel#5057 for reference.

[jayconrod]

I updated this PR to tip of master. It looks like the aarch64 platform didn't actually make it into Bazel 0.15.0 (which is now the rules_go minimum supported version). I can confirm the build works with Bazel 0.16.0rc4 at least, but I can't make 0.16.0 the minimum version yet.

[vielmetti]

Thanks @jayconrod . What is the release cadence for Bazel? Trying to determine at what pace I need to track this to get these changes incorporated into projects up and downstream.

[jayconrod]

@vielmetti Bazel aims for a release every month, but they are quite late this month. You can track this month's release at bazelbuild/bazel#5058.

[lubinsz]

@jayconrod
Can you merge it?
I have tested this patch, use bazel 0.16.0 to compile gvisor@Arm64. It works fine.
For your reference:

root@bin:/go/src/github.com/google/gvisor-debug# bazel build runsc
Starting local Bazel server and connecting to it...
...................
INFO: SHA256 (https://github.com/lubinsz/rules_go/archive/99e775b541860087f6b7a82203267cd985460f85.tar.gz) = fca945b84fd882ada7c55f8da7a0253161614ab54e4ca3b5202199c346015ebc
INFO: SHA256 (https://codeload.github.com/google/protobuf/zip/106ffc04be1abf3ff3399f54ccf149815b287dd9) = 4d127e1c3608803bc845cc4b3c8c42a6a16263b6ddcb932b53049e7ec8101398
INFO: Analysed target //runsc:runsc (182 packages loaded).
INFO: Found 1 target...
Target //runsc:runsc up-to-date:
bazel-bin/runsc/linux_arm64_pure_stripped/runsc
INFO: Elapsed time: 131.884s, Critical Path: 56.17s
INFO: 585 processes: 575 linux-sandbox, 10 local.
INFO: Build completed successfully, 601 total actions
root@bin:/go/src/github.com/google/gvisor-debug#
root@bin:/go/src/github.com/google/gvisor-debug#
root@bin:/go/src/github.com/google/gvisor-debug# uname -a
Linux bin 4.15.0-rc8+ #1 SMP Mon Jul 16 14:37:25 CST 2018 aarch64 aarch64 aarch64 GNU/Linux
root@bin:/go/src/github.com/google/gvisor-debug#

[jayconrod]

@lubinsz This breaks on Bazel 0.15, which is our minimum supported version.

I'm planning to tag a release of rules_go next week. We can bump the minimum supported Bazel version after that and then merge this.

[steeve]

This might need rebasing on master too

[ArielleA]

I'll rebase it once 0.17 is out, allow us to get some more issues with the Arm64 port resolved.

[lubinsz]

@ArielleA @jayconrod @steeve
Can we merge it now?

[jayconrod]

@lubinsz Now that Bazel 0.17 is out, we should be fine. Merged.

[lubinsz]

@jayconrod
Hi,
When will the new version be released with this patch in https://github.com/bazelbuild/rules_go/releases?
Thanks.

[jayconrod]

@lubinsz I expect we'll tag a major release this week.