Re: Desktops on non-x86_64 systems

["Ludovic Courtès" <ludo@gnu.org>]

Hi!

Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:

> I've updated the branch wip-cross-built-rust; it seems to build and run
> OK (although running the binary produced by compiling hello.rs with the
> cross-built i686-linux rustc in a 32 bit VM took 47 sec (!?)),
> apparently hanging on something before outputting correctly the message
> and exiting with 0.
>
> I'd now like to figure out the top-level plumbing required to get this
> rust-i686-linux x86-64 package accepted in the real of i686-linux
> packages (cross the architecture boundary).  Is this even possible in
> Guix?
>
> In other words, I'd like the i686 architecture to be able to use this
> rust-i686-linux cross built from x86_64 as if it was a *native* package.

It’s not possible as it would imply that i686 is able to run x86_64
code.

What we’d need to do is “cut the dependency graph” at the architecture
boundary, similar to what’s described in
<https://guix.gnu.org/manual/devel/en/html_node/Porting.html>.

Concretely, we’d cross-build Rust for i686 once; we’d put it in a
tarball, store it at ftp.gnu.org, and make the rust 1.54 package (or
whatever that is) be equal so that tarball, unpacked, when the current
system is i686.  (Similar to the ‘guile-bootstrap’ package.)

It does mean that the cross-built Rust must be statically linked.

To reduce the risks associated with binary blobs, the Rust build should
ideally be reproducible, so that anyone can verify that the thing we put
at ftp.gnu.org is indeed Rust as cross-compiled from x86_64.

How long is the road ahead in your opinion?

Thanks for working on it!

Ludo’.