Re: rust: NetBSD 9 earmv7, version selection, RUST_TYPE

[Tobias Nygren <tnn%NetBSD.org@localhost>]

On Tue, 06 May 2025 12:39:13 -0400
Greg Troxel <gdt%lexort.com@localhost> wrote:

> Thomas Klausner <wiz%gatalith.at@localhost> writes:
> 
> > Do I understand this correctly, that we should just switch NetBSD 9.x
> > earm* to use binary rust, like in the attached diff?
> >
> > (Then we'd have one rust version on all platforms again, allowing some
> > currently stuck package upgrades.)
> 
> Sure, but we should go further:
> 
>   Why is this limited to 9?   Can someone with a reasonable computer
>   running armv7hf-el on NetBSD 10, like a RPI3 with 1G of RAM, expect
>   that lang/rust will build?  I don't think so.
> 
>   Why is this limited to NetBSD?  I don't have the impression there's
>   anything wrong with NetBSD arm.  Rather, it's that rust is
>   fundamentally huge.   Can people running FreeBSD or Linux build
>   lang/rust (not install a binary, build) on a machine with 1G of RAM?

The reasonable thing to do for someone with such a computer would be to
build their packages in a 32-bit chroot on a 64-bit machine with
many CPU cores and at least 8GB of RAM. However, not even that is
guaranteed to help here. The problem is not physical memory, it is that
we start to hit the userland VA limit. evbarm uses a 2GB/2GB
userland/kernel VA split. The only practical way to get rust onto such
32-bit ports is to cross-compile it.

i386 is different in that it has a 3GB/1GB userland/kernel VA split
so it generally fairs better there. For now, at least.

It might be possible and even somewhat practical to build rust on earm
with a 3GB/1GB VA split and some swap space. Some board configs do set
KERNEL_BASE_EXT=0xc0000000 but that's not the default. Not sure why.

I am not a fan of 3rd party binary packages but it seems it might be the
only sane default for 2G/2G ports and it ok as long as the option
to override the default is retained.

-Tobias