Subject: Re: [bug#31934] [PATCH] services: sound: Properly handle alsa-plugins.

From: Oleg Pykhalov <[email-masked]>
Date: Sun, 24 Jun 2018 13:44:54 +0300

Hello,

[email-masked] (宋文武) writes:

> Julien Lepiller <[email-masked]> writes:

[…]

> Hello, after some hours of searching...  I found that we can use the
> 'lib' option in 'pcm_type' and 'ctl_type' to specify the library path
> for alsa plugins, e.g:

Thats a nice hack :-)  Thank you for working on this.

[…]

> So I think we can make our 'alsa-service' do this, instead of patching
> alsa-lib for 'ALSA_PLUGIN_DIR'.

Done.  Here is a patch which I tested on my machine by ‘system reconfigure’:
From 22186e76d991a47e7057d1abe23af02b52f8153b Mon Sep 17 00:00:00 2001
From: Oleg Pykhalov <[email-masked]>
Date: Sun, 24 Jun 2018 13:18:53 +0300
Subject: [PATCH] services: sound: Properly handle alsa-plugins.

* gnu/services/sound.scm (<alsa-configuration>)[alsa-plugins]: New field.
(alsa-config-file): Add this.
* doc/guix.texi (Sound Services): Document this.
---
 doc/guix.texi          |  3 +++
 gnu/services/sound.scm | 31 +++++++++++++++++++++++--------
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index 74c10e4bb..e5366ac6b 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -13152,6 +13152,9 @@ See below for details about @code{alsa-configuration}.
 Data type representing the configuration for @code{alsa-service}.
 
 @table @asis
+@item @code{alsa-plugins} (default: @var{alsa-plugins})
+@code{alsa-plugins} package to use.
+
 @item @code{pulseaudio?} (default: @var{#t})
 Whether ALSA applications should transparently be made to use the
 @uref{http://www.pulseaudio.org/, PulseAudio} sound server.
diff --git a/gnu/services/sound.scm b/gnu/services/sound.scm
index 5fe555e8b..2b2cabd7b 100644
--- a/gnu/services/sound.scm
+++ b/gnu/services/sound.scm
@@ -26,6 +26,7 @@
   #:use-module (guix packages)
   #:use-module (guix records)
   #:use-module (guix store)
+  #:use-module (gnu packages linux)
   #:use-module (gnu packages pulseaudio)
   #:use-module (ice-9 match)
   #:export (alsa-configuration
@@ -44,17 +45,31 @@
 
 (define-record-type* <alsa-configuration>
   alsa-configuration make-alsa-configuration alsa-configuration?
+  (alsa-plugins alsa-configuration-alsa-plugins ;<package>
+                (default alsa-plugins))
   (pulseaudio?   alsa-configuration-pulseaudio? ;boolean
                  (default #t))
   (extra-options alsa-configuration-extra-options ;string
                  (default "")))
 
-(define (alsa-config-file config)
-  "Return the ALSA configuration file corresponding to CONFIG."
-  (plain-file "asound.conf"
-              (string-append "# Generated by 'alsa-service'.\n\n"
-                             (if (alsa-configuration-pulseaudio? config)
-                                 "# Use PulseAudio by default
+(define alsa-config-file
+  ;; Return the ALSA configuration file.
+  (match-lambda
+    (($ <alsa-configuration> alsa-plugins pulseaudio? extra-options)
+     (mixed-text-file "asound.conf"
+                      "# Generated by 'alsa-service'.\n\n"
+                      ;; if pulseaudio?
+                      "# Use PulseAudio by default
+pcm_type.pulse {
+  lib " #~(string-append #$alsa-plugins:pulseaudio
+                         "/lib/alsa-lib/libasound_module_pcm_pulse.so") "
+}
+
+ctl_type.pulse {
+  lib " #~(string-append #$alsa-plugins:pulseaudio
+                         "/lib/alsa-lib/libasound_module_ctl_pulse.so") "
+}
+
 pcm.!default {
   type pulse
   fallback \"sysdefault\"
@@ -69,8 +84,8 @@ ctl.!default {
   fallback \"sysdefault\"
 }
 "
-                                 "")
-                             (alsa-configuration-extra-options config))))
+                           ""
+                      extra-options))))
 
 (define (alsa-etc-service config)
   (list `("asound.conf" ,(alsa-config-file config))))
-- 
2.17.1

[…]

Thanks,
Oleg.