Re: [arch-ports] Easier to cross-bootstrap or bootstrap with another distro?

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:

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

Hello,

Hi,

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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).

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- 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.

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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