Re: [Buildroot] [PATCH v7 4/4] package/go: use host compiler when go-bootstrap unsupported

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello Christian,

On Tue, 11 Jul 2023 15:08:49 -0700
Christian Stewart via buildroot <buildroot@buildroot.org> wrote:

> All Go compiler versions > 1.4.x (old) are written in Go, and require a existing
> compiled Go version to use to build from source.
> 
> https://golang.org/doc/install/source#bootstrapFromSource
> 
> The process for "bootstrapping" the Go compiler in Buildroot is:
> 
> 1. Compile a C/C++ cross-compiler (gcc) as the host toolchain.
> 2. Build go-bootstrap-stage1 (which is Go 1.4.x and written in C)
> 3. Build go-bootstrap-stage2 (which is Go 1.19.x and written in Go)
> 3. Build go 1.20 (written in Go) using go-bootstrap-stage2.
> 
> go-bootstrap-stage1 does not work on 64-bit arm. The Go 1.4.x bootstrap compiler
> is compatible with x86, x86_64, and arm (32 bit) only.
> 
> This patch adds a fallback to require a host Go compiler to build host-go when
> BR2_PACKAGE_HOST_GO_BOOTSTRAP_STAGE2_ARCH_SUPPORTS is not set.
> 
> Signed-off-by: Christian Stewart <christian@aperture.us>

I understand the need, but I'd like to explore other options, namely
using pre-compiled Go compilers, which we would also like to support in
order to have the ability to run "make legal-info", or build Go
packages without necessarily having to build a Go compiler from
scratch. Like what we do for Rust, where you can chose to either use a
pre-built Rust compiler, or build your own with Buildroot.

For Go, I think we could imagine two options:

(a) You use a pre-built Go compiler as a replacement for package/go.
    This would work for architectures/configurations for which
    pre-built Go compilers are available. We would then move package/go
    as a virtual package, with package/go-src being the provider that
    builds the Go compiler from source, and package/go-bin being the
    provider that downloads/installs a pre-built Go compiler.

(b) You use a pre-built Go compiler as a replacement for
    package/go-bootstrap-stage2, i.e you still build the final Go
    compiler from source, but all the bootstrapping is skipped by using
    a pre-built Go compiler for the host. Would this option also
    resolve your use-case of building on ARM64? In other words, is
    there a Go compiler available pre-built for ARM64?

Best regards,

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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