Michael Pratt

cc @randall77 Overall this sounds great. The main concern I have up front here is that growing happens all at once rather than incrementally. Could you explain more why that...

I'm starting prototyping with this testing out AWS Mac instances, first by creating some standard reverse builders.

https://go.dev/cl/430696 added an AWS darwin-amd64 reverse builder (`darwin-amd64-12-aws`), which I've set up manually with a launchd service. It actually almost "just works". All of the x/ repos seem to be...

We now have three hosts running six reverse builder VMs fully set up and (almost) ready. There is one failing test (https://build.golang.org/log/c40b5c45d0dc28318fd9ad0149efddfe39ff27d7) because an extra deprecation warning printed by bash....

FWIW, the `forkstress` program did not reproduce the problem on openbsd either even though there was a clear AMD issue on openbsd. It is possible that the issue on openbsd...

cc @golang/runtime @golang/illumos

Note that using runtime.Callers should avoid this lock contention.

I also agree that we should at least be consistent in the various interfaces. Stepping back on the proposal, I'm not sure that we need to add an explicit API...

We've previously fixed this for ppc64 (#42178) with https://go.dev/cl/266202 and later https://go.dev/cl/385796. The latter is probably what we want if mips really doesn't use r2.

@cherrymui pointed out that this register may only be used for a few system calls. But if the kernel does not clobber it, it may be best to have Syscall6...