Thank you for your input. The Debian port in question seems to have been bootstrapped by cross compiling, but the later stages are mostly done with qemu-user chroots. So there's still hope that I can qemu-user all the way if my host is fast enough... Have a nice day. Sincerely ________________________________________ From: Andreas Baumann Sent: Wednesday, April 28, 2021 21:57 To: Sijie Bu Cc: Discussion regarding the porting of Arch Linux to non-x86_64 architectures Subject: Re: Easier to cross-bootstrap or bootstrap with another distro?

Reply-To: Andreas Baumann In-Reply-To:

On Mon, Apr 26, 2021 at 09:00:04AM +0000, Sijie Bu via arch-ports wrote:

...

(This message was originally posted on arch-general and I was redirected by a member to this list.)

Hello,

Hi,

...

I am about to start working as an intern at CIP United, a company focusing on MIPS chips, and I will be bootstrapping Arch Linux onto the MIPS64r6 architecture, in a fashion similar to Arch Linux ARM.

I have checked the Arch Linux MIPS project, but it seems to be inactive for years now. I have checked ArchWiki's DeveloperWiki section, but it seems to lack guidelines or suggestions on bootstrapping Arch onto a new architecture. Therefore I have a few questions: - Intuitively, I think I should cross-compile the packages of the "core" section (sans a few x64-specific packages) and build a bootable rootfs, but I was having some trouble finding how should I set makepkg to cross-compile. Do I just set up an Arch developer environment as usual, but substitute the toolchain with the cross ones?

I did a "cross-compile" from x86_64 to i486 some time ago, you can maybe find some useful information in https://git.archlinux32.org/bootstrap32/.

I can also recommend the oakensource's RISC-V port at https://github.com/oaken-source/parabola-cross-bootstrap

Basically yes, you'll need a cross toolchain for MIPS, either from the AUR or use a cross-platorm distro like http://t2sde.org/ to bootstrap directly from MIPS (in qemu or so).

...

- Does adding a new architecture require modifications to the pacman source code? Or pacman itself should support new architectures? I have also tried looking at pacman source code, and it seems to not have hard-coded list of architectures, but I am not 100% sure about this (if I'll have to modify the source code of pacman, I will be emailing the pacman-dev mailing list regarding their policies on patches etc.).

In theory pacman should be quite portable (it runs at least on x86_64, IA32, ARM 32-bit, AARCH64). So the typical 32-/64-bit issues should have been fixed.

You will have to make pacman know about your new architecture (and eventually subarchitectures). See our fork of pacman on https://git.archlinux32.org/pacman/ (basically auto-detection for SSE2, support for sub-architectures 'i486', 'i686', 'pentium4').

Most work I expect in breaking cycles and dependencies in PKGBUILDs.

...

Thank you for your time and have a nice day. Sincerely _______________________________________________ arch-ports mailing list arch-ports@lists.archlinux.org https://lists.archlinux.org/listinfo/arch-ports

Happy porting, feel free to ask questions on IRC at #archinux-ports or #archlinux32. :-)

Cheers

Andreas

-- Andreas Baumann Trottenstrasse 20 CH-8037 Zuerich Telefon: +41(0)76/373 01 29 E-mail: mail@andreasbaumann.cc Homepage: www.andreasbaumann.cc

On Thu, Apr 29, 2021 at 12:52:06AM +0000, Sijie Bu wrote:

Hello,

I do have a quick follow-up question. My friends who works for CIP United told me that they've already got a full Debian port, and it can be run with either qemu-system or qemu-user (unfortunately it seems actual hardware for MIPS64 R6 aren't available yet, probably due to the global silicon shortage). So I'm wondering will it be easier if I first compile pacman against Debian libraries, and use that to natively bootstrap a stage1 image than using cross compiler for bootstrapping?

Hi, You can in this case start right away to build a minimal Archlinux chroot on Debian containing all essential packages (at least the C/C++ toolchain, base packages and pacman and its dependencies). It's definitely easier to do so, as you don't have to deal with cross-compilation issues in packages. On the other hand running this in qemu might me unthinkable slow, without ccache/distcc-ing the load to the native CPU, this will take forever.

Thank you for your time and have a nice day.

Sincerely

Cheers Andreas -- Andreas Baumann Trottenstrasse 20 CH-8037 Zuerich Telefon: +41(0)76/373 01 29 E-mail: mail@andreasbaumann.cc Homepage: www.andreasbaumann.cc