[systemd-devel] [PATCH 1/2] Don't use ALSA card id in ID_ID

[Lennart Poettering]

On Fri, 10.04.15 22:27, Adam Goode (agoode at google.com) wrote:

> The ALSA id sysattr is generated by the sound subsystem and is not
> a stable identifier. It is generated though some string manipulation
> then made unique if there is a conflict. This means that it is
> enumeration-dependent and shouldn't be used for ID_ID.
> 
> If ID_ID is supposed to be system-unique, it is not already since
> for firewire it is generated from the guid and there are broken
> firewire devices that have duplicate guids across devices.

Hmm, this patch pretty much reverts
ed1b2d9fc7d5c5bfe2a67b0b8ff9e5ea8694268e. Now I am not sure if that
commit from 6 years ago was a good idea, but we should have some
clarity about this.

What is ID_ID actually supposed to be? Should it really be system
unique?

I do have the suspicion this is something that better should be fixed in
PA rather then in these udev rules, so I figure your patch might be a
good idea?

Opinions?

If we apply the patch somebody should at least post a bug report
against PA to be aware of this change.

> ---
>  rules/78-sound-card.rules | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/rules/78-sound-card.rules b/rules/78-sound-card.rules
> index 295f490..bd7a994 100644
> --- a/rules/78-sound-card.rules
> +++ b/rules/78-sound-card.rules
> @@ -49,8 +49,8 @@ SUBSYSTEMS=="firewire", GOTO="skip_pci"
>  SUBSYSTEMS=="pci", ENV{ID_BUS}="pci", ENV{ID_VENDOR_ID}="$attr{vendor}", ENV{ID_MODEL_ID}="$attr{device}"
>  LABEL="skip_pci"
>  
> -ENV{ID_SERIAL}=="?*", ENV{ID_USB_INTERFACE_NUM}=="?*", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}-$env{ID_USB_INTERFACE_NUM}-$attr{id}"
> -ENV{ID_SERIAL}=="?*", ENV{ID_USB_INTERFACE_NUM}=="", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}-$attr{id}"
> +ENV{ID_SERIAL}=="?*", ENV{ID_USB_INTERFACE_NUM}=="?*", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}-$env{ID_USB_INTERFACE_NUM}"
> +ENV{ID_SERIAL}=="?*", ENV{ID_USB_INTERFACE_NUM}=="", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}"
>  
>  IMPORT{builtin}="path_id"
>  
> -- 
> 2.2.0.rc0.207.ga3a616c
> 
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Lennart

-- 
Lennart Poettering, Red Hat