[bug#55431] [PATCH] guix: cpu: recognize other architectures.

[Julien Lepiller <julien@lepiller.eu>]

[-- Attachment #1: Type: text/plain, Size: 1533 bytes --]

Hi Guix!

The attached patch lets (guix cpu) recognize other architectures. The
code of (current-cpu) is based on the content of /proc/cpuinfo which
can be pretty different on non-intel architectures. For instance,
here's a sample from an armhf machine:

processor	: 0
model name	: ARMv7 Processor rev 4 (v7l)
BogoMIPS	: 45.47
Features	: half thumb fastmult vfp edsp thumbee neon vfpv3 tls
vfpv4 idiva idivt vfpd32 lpae evtstrm CPU implementer	: 0x41
CPU architecture: 7
CPU variant	: 0x0
CPU part	: 0xc07
CPU revision	: 4

In particular, there's no flags entry, so (current-cpu) doesn't stop
until eof, and returns #f.

It's an issue because a test uses this code, for testing manifests with
--tune. If no cpu is returned, the test crashes:

In guix/transformations.scm:
   864:25  1 (_ _ _ _ ((package ad-hoc-package "gcc-toolchain")
(<E2><80><A6>) <E2><80><A6>)) In guix/cpu.scm:
     94:2  0 (cpu->gcc-architecture #f)

Since the test fails, the "guix" package doesn't build, and I can't
reconfigure on armhf or aarch64. (well armhf has other issues right
now...)

The attached patch changes the logic of the code to read all lines,
find information about the CPU even if it's an ARM CPU, and returns
always something (to prevent the crash) when it reads eof. This means
that it will return architecture information about the last CPU,
instead of the first. I don't think that's an issue because this code
is used for --tune which really only works on intel where you don't
have multiple CPUs with too different features.

WDYT?

[-- Attachment #2: 0001-guix-cpu-Recognize-other-architectures.patch --]
[-- Type: text/x-patch, Size: 3085 bytes --]

From 32ebfc93f838eba74c1f1188f7d23363f32ee94b Mon Sep 17 00:00:00 2001
From: Julien Lepiller <julien@lepiller.eu>
Date: Sun, 15 May 2022 19:01:37 +0200
Subject: [PATCH] guix: cpu: Recognize other architectures.

* guix/cpu.scm (current-cpu): Recognize aarch64.
---
 guix/cpu.scm | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/guix/cpu.scm b/guix/cpu.scm
index a44cd082f1..7e25fcb9cf 100644
--- a/guix/cpu.scm
+++ b/guix/cpu.scm
@@ -62,31 +62,48 @@ (define (prefix? prefix)
       (lambda (port)
         (let loop ((vendor #f)
                    (family #f)
-                   (model #f))
+                   (model #f)
+                   (flags '()))
           (match (read-line port)
             ((? eof-object?)
-             #f)
+             (cpu (utsname:machine (uname))
+                  vendor family model (list->set flags)))
             ((? (prefix? "vendor_id") str)
              (match (string-tokenize str)
                (("vendor_id" ":" vendor)
-                (loop vendor family model))))
+                (loop vendor family model flags))))
+            ((? (prefix? "CPU implementer") str)
+             (match (string-tokenize str)
+               (("CPU" "implementer" ":" vendor)
+                (loop vendor family model flags))))
             ((? (prefix? "cpu family") str)
              (match (string-tokenize str)
                (("cpu" "family" ":" family)
-                (loop vendor (string->number family) model))))
+                (loop vendor (string->number family) model flags))))
+            ((? (prefix? "CPU architecture") str)
+             (match (string-tokenize str)
+               (("CPU" "architecture:" family)
+                (loop vendor family model flags))))
             ((? (prefix? "model") str)
              (match (string-tokenize str)
                (("model" ":" model)
-                (loop vendor family (string->number model)))
+                (loop vendor family (string->number model) flags))
                (_
-                (loop vendor family model))))
+                (loop vendor family model flags))))
+            ((? (prefix? "CPU part") str)
+             (match (string-tokenize str)
+               (("CPU" "part" ":" model)
+                (loop vendor family (string->number (substring model 2) 16) flags))))
             ((? (prefix? "flags") str)
              (match (string-tokenize str)
                (("flags" ":" flags ...)
-                (cpu (utsname:machine (uname))
-                     vendor family model (list->set flags)))))
+                (loop vendor family model flags))))
+            ((? (prefix? "Features") str)
+             (match (string-tokenize str)
+               (("Features" ":" flags ...)
+                (loop vendor family model flags))))
             (_
-             (loop vendor family model))))))))
+             (loop vendor family model flags))))))))
 
 (define (cpu->gcc-architecture cpu)
   "Return the architecture name, suitable for GCC's '-march' flag, that
-- 
2.35.1