[Pkg-alsa-devel] Bug#800572: Bug#800572: CONFIG_UEVENT_HELPER=n kernel confuses alsactl restore

[Elimar Riesebieter]

Control: reassign -1 udev

As alsas' udev rules are installed by udev package.

-- 
   Elimar

* Trent W. Buck <trentbuck at gmail.com> [2015-10-01 11:26 +1000]:

> Package: alsa-utils
> Version: 1.0.29-1
> Severity: minor
> 
> I spotted this message when studying alsa-utils' udev rules:
> 
>     # alsactl -E HOME=/run/alsa --file /dev/null restore 0
>     No state is present for card PCH
> **  alsactl: sysfs_init:48: sysfs path '/sys' is invalid
> 
>     Found hardware: "HDA-Intel" "Realtek ALC662 rev3" "HDA:10ec0662,10ec0662,00100300" "0x10ec" "0x0662"
>     Hardware is initialized using a generic method
>     No state is present for card PCH
> 
>     # echo $?
>     99
> 
> This code assumes that a working /sys will have a /sys/kernel/uevent_helper.
> This is not a safe assumption in custom 3.16+ kernels.
> See also https://bugs.debian.org/752742
> Also /usr/share/doc/systemd/README.gz calls it a "legacy" interface,
> though I think it is still essential elsewhere (e.g. busybox mdev).
> 
>     alsactl/init_sysfs.c-32-static int sysfs_init(void)
>     alsactl/init_sysfs.c:46:        strlcat(sysfs_test, "/kernel/uevent_helper", sizeof(sysfs_test));
>     alsactl/init_sysfs.c-47-        if (access(sysfs_test, F_OK)) {
>     alsactl/init_sysfs.c-48-                error("sysfs path '%s' is invalid\n", sysfs_path);
>     alsactl/init_sysfs.c-49-                return -errno;
>     alsactl/init_sysfs.c-50-        }
> 
> I don't know what sysfs_init() *should* check for.
> 
> I don't know what alsactl does differently if it thinks /sys is working.
> 
> alsactl restore *does* change my mixer levels, so this might be a non-issue:
> 
>     # echo 1 >/sys/class/sound/hdaudioC0D2/reconfig
>     # amixer >before
>     # alsactl -E HOME=/run/alsa --file /dev/null restore 0
>     [...]
>     # amixer >after
>     # cmp before after
>     before after differ: byte 164, line 5
> 
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