RISCV porting effort

[Efraim Flashner]

Last week my HiFive Umatched¹ board came and was quite the object of
interest at the local computer store as I picked up a case, PSU and
graphics card.

Couple of observations about the board first:
It boots very slowly. I think it takes about 5 minutes from power-on to
being able to sign in at TTY1.
It has an NVMe slot which I haven't populated yet.
Ubuntu has an image for the board² which booted up just fine and I'm
using, since I didn't want to spend too long getting Debian to run on
the board.
Upstream u-boot support was merged days ago³ so we should be able to add
support to our u-boot package soon-ish™.

Porting Guix comes with two parts: building the bootstrap-tarballs and
adding support for the new architecture in (gnu packages bootstrap).
Support for riscv was added to GCC with 7.1.0 so I had to bump the
bootstrap GCC to 7 (and adjust some inputs), and guile-2.0.14 didn't
known the endianness of riscv64 so instead of patching it I bumped the
bootstrap guile to 3.0. I uploaded my bootstrap-tarballs to my regular
spot after signing them and switched over to the riscv machine.

Building Guix from sources is much easier thanks to the work of Vagrant,
I was able to apt install most of the dependencies on riscv. The
packaged version of guile-zlib was too old in 21.04 so I built that from
source (0.1.0 is available in Debian experimental), and I also had to
build gnutls from source for the guile-3.0 bindings. I added the riscv
binaries to (gnu packages bootstrap) and temporarily switched the
raw-build function to look for 3.0 guile libraries instead of 2.0.

Where I'm at right now:
Downloading using the daemon (builtin:download) fails currently, it says
it doesn't have permissions to open-file to write downloaded files to
the store.
I haven't built anything using the bootstrap binaries to see if they
actually work yet.


(ins)efraim@unmatched:~$ neofetch --off
efraim@unmatched
----------------
OS: Ubuntu 21.04 riscv64
Host: SiFive HiFive Unmatched A00
Kernel: 5.11.0-1007-generic
Uptime: 3 days, 15 hours, 57 mins
Packages: 782 (dpkg)
Shell: bash 5.1.4
Terminal: /dev/pts/0
CPU: (4)
GPU: NVIDIA GeForce GT 730
Memory: 350MiB / 15995MiB

(ins)efraim@unmatched:~$ lscpu
Architecture:        riscv64
Byte Order:          Little Endian
CPU(s):              4
On-line CPU(s) list: 0-3
Thread(s) per core:  4
Core(s) per socket:  1
Socket(s):           1
L1d cache:           32 KiB
L1i cache:           32 KiB
L2 cache:            2 MiB


¹https://www.sifive.com/boards/hifive-unmatched
²http://cdimage.ubuntu.com/releases/21.04/release/
³https://source.denx.de/u-boot/u-boot/-/commit/d8729a114e1e98806cffb87d2dca895f99a0170a

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Efraim Flashner   <efraim@flashner.co.il>   אפרים פלשנר
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riscv-make-bootstrap.diff
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riscv-bootstrap.diff
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bootstrap-guix-without-packaging.md
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