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Old 03-20-2012, 11:35 PM
Pandu Poluan
 
Default mdev: sound is only working some of the time.

On Mar 21, 2012 5:36 AM, "Alan Mackenzie" <acm@muc.de> wrote:

>

> Hi, all.

>

> Got a problem with my system running under mdev. *When I try to play CDs

> (with aqualung feeding into PulseAudio), no sound comes out. *However,

> when I listen to an audio section from a newspaper page such as

> www.tagesschau.de (no idea what audio format) it works.

>

> Clearly this is something to do with mdev. *I had a look at the devices

> in /dev, searching for those in group audio. *Under udev, I find the

> following as device nodes:

>

> adsp audio dsp mixer mixer1 sequencer sequencer2.

>

> Under mdev, all of these bar one are symlinks into the real nodes in a

> subdirectory. *The odd man out is mixer1 which is a device node, but

> with owner/group begin root/root (rather than root/audio).

>

> Can anybody suggest any fix, or further areas of exploration? *Thanks!

>


That's indicative that it's the kernel doing the populating (that is, everything belongs to root:root). That means, mdev hasn't got the chance to 'restructure' the /dev directory (that is, rename and/or move and/or chown devices).



Does 'mdev -s' exist in your /sbin/linuxrc? Can you post your linuxrc here?


Rgds,
 
Old 03-21-2012, 10:11 AM
Alan Mackenzie
 
Default mdev: sound is only working some of the time.

Hello, Walt.

On Tue, Mar 20, 2012 at 04:23:14PM -0700, walt wrote:
> On 03/20/2012 03:31 PM, Alan Mackenzie wrote:
> > Hi, all.

> > Got a problem with my system running under mdev. When I try to play CDs
> > (with aqualung feeding into PulseAudio), no sound comes out. However,
> > when I listen to an audio section from a newspaper page such as
> > www.tagesschau.de (no idea what audio format) it works.

> > Clearly this is something to do with mdev. I had a look at the devices
> > in /dev, searching for those in group audio. Under udev, I find the
> > following as device nodes:

> > adsp audio dsp mixer mixer1 sequencer sequencer2.

> > Under mdev, all of these bar one are symlinks into the real nodes in a
> > subdirectory. The odd man out is mixer1 which is a device node, but
> > with owner/group begin root/root (rather than root/audio).

> > Can anybody suggest any fix, or further areas of exploration? Thanks!

> Can you do chown root:audio on the mixer as a test?

Done so. It didn't help. It's mightily curious why that one device is
different from the others. It's not so under udev.

Anyhow I found the problem. It was pulseaudio. I rebuilt it with its
udev use flag taken out. This didn't help.

Then I rebuilt aqualung without the pulseaudio flag, and now things work.

As I type, I am listening to Mahler's second symphony, played by the
Bamberger Symphoniker conducted by Jonathan Nott. I can recomment Mahler
for when things aren't going quite according to plan, and this recording
in particular.

--
Alan Mackenzie (Nuremberg, Germany).
 
Old 03-21-2012, 10:17 AM
Alan Mackenzie
 
Default mdev: sound is only working some of the time.

Hello, Pandu.

On Wed, Mar 21, 2012 at 07:35:14AM +0700, Pandu Poluan wrote:
> On Mar 21, 2012 5:36 AM, "Alan Mackenzie" <acm@muc.de> wrote:

> > Hi, all.

> > Got a problem with my system running under mdev. When I try to play CDs
> > (with aqualung feeding into PulseAudio), no sound comes out. However,
> > when I listen to an audio section from a newspaper page such as
> > www.tagesschau.de (no idea what audio format) it works.

> > Clearly this is something to do with mdev. I had a look at the devices
> > in /dev, searching for those in group audio. Under udev, I find the
> > following as device nodes:

> > adsp audio dsp mixer mixer1 sequencer sequencer2.

> > Under mdev, all of these bar one are symlinks into the real nodes in a
> > subdirectory. The odd man out is mixer1 which is a device node, but
> > with owner/group begin root/root (rather than root/audio).

> > Can anybody suggest any fix, or further areas of exploration? Thanks!


> That's indicative that it's the kernel doing the populating (that is,
> everything belongs to root:root).

No, it was just that one device belonging to root:root. This is
mysterious indeed.

> That means, mdev hasn't got the chance to 'restructure' the /dev
> directory (that is, rename and/or move and/or chown devices).

> Does 'mdev -s' exist in your /sbin/linuxrc? Can you post your linuxrc
> here?

mdev -s wasn't in my /sbin/linuxrc. It is now. It hasn't made any
difference to that wayward device.

As I said to Walt, I've solved the problem by turfing out pulseaudio.

> Rgds,

--
Alan Mackenzie (Nuremberg, Germany).
 
Old 03-21-2012, 11:49 AM
Pandu Poluan
 
Default mdev: sound is only working some of the time.

On Mar 21, 2012 6:22 PM, "Alan Mackenzie" <acm@muc.de> wrote:

>

> Hello, Pandu.

>

> On Wed, Mar 21, 2012 at 07:35:14AM +0700, Pandu Poluan wrote:

> > On Mar 21, 2012 5:36 AM, "Alan Mackenzie" <acm@muc.de> wrote:

>

> > > Hi, all.

>

> > > Got a problem with my system running under mdev. *When I try to play CDs

> > > (with aqualung feeding into PulseAudio), no sound comes out. *However,

> > > when I listen to an audio section from a newspaper page such as

> > > www.tagesschau.de (no idea what audio format) it works.

>

> > > Clearly this is something to do with mdev. *I had a look at the devices

> > > in /dev, searching for those in group audio. *Under udev, I find the

> > > following as device nodes:

>

> > > adsp audio dsp mixer mixer1 sequencer sequencer2.

>

> > > Under mdev, all of these bar one are symlinks into the real nodes in a

> > > subdirectory. *The odd man out is mixer1 which is a device node, but

> > > with owner/group begin root/root (rather than root/audio).

>

> > > Can anybody suggest any fix, or further areas of exploration? *Thanks!

>

>

> > That's indicative that it's the kernel doing the populating (that is,

> > everything belongs to root:root).

>

> No, it was just that one device belonging to root:root. *This is

> mysterious indeed.

>

> > That means, mdev hasn't got the chance to 'restructure' the /dev

> > directory (that is, rename and/or move and/or chown devices).

>

> > Does 'mdev -s' exist in your /sbin/linuxrc? Can you post your linuxrc

> > here?

>

> mdev -s wasn't in my /sbin/linuxrc. *It is now. *It hasn't made any

> difference to that wayward device.

>

> As I said to Walt, I've solved the problem by turfing out pulseaudio.

>


Strange...


Do you use mdev to handle hotplugs, btw?


Rgds,
 
Old 03-21-2012, 12:02 PM
Alan Mackenzie
 
Default mdev: sound is only working some of the time.

On Wed, Mar 21, 2012 at 07:49:02PM +0700, Pandu Poluan wrote:
> On Mar 21, 2012 6:22 PM, "Alan Mackenzie" <acm@muc.de> wrote:

> > Hello, Pandu.

> > On Wed, Mar 21, 2012 at 07:35:14AM +0700, Pandu Poluan wrote:
> > > On Mar 21, 2012 5:36 AM, "Alan Mackenzie" <acm@muc.de> wrote:

> > > > Hi, all.

> > > > Got a problem with my system running under mdev. When I try to
> > > > play CDs (with aqualung feeding into PulseAudio), no sound comes
> > > > out. However, when I listen to an audio section from a newspaper
> > > > page such as www.tagesschau.de (no idea what audio format) it
> > > > works.

> > > > Clearly this is something to do with mdev. I had a look at the
> > > > devices in /dev, searching for those in group audio. Under udev,
> > > > I find the following as device nodes:

> > > > adsp audio dsp mixer mixer1 sequencer sequencer2.

> > > > Under mdev, all of these bar one are symlinks into the real nodes
> > > > in a subdirectory. The odd man out is mixer1 which is a device
> > > > node, but with owner/group begin root/root (rather than
> > > > root/audio).

> > > > Can anybody suggest any fix, or further areas of exploration?
> > > > Thanks!


> > > That's indicative that it's the kernel doing the populating (that
> > > is, everything belongs to root:root).

> > No, it was just that one device belonging to root:root. This is
> > mysterious indeed.

> > > That means, mdev hasn't got the chance to 'restructure' the /dev
> > > directory (that is, rename and/or move and/or chown devices).

> > > Does 'mdev -s' exist in your /sbin/linuxrc? Can you post your
> > > linuxrc here?

> > mdev -s wasn't in my /sbin/linuxrc. It is now. It hasn't made any
> > difference to that wayward device.

> > As I said to Walt, I've solved the problem by turfing out pulseaudio.


> Strange...

> Do you use mdev to handle hotplugs, btw?

You mean, like sticking in a USB stick, or turning my printer on? Yes, I
do.

> Rgds,

--
Alan Mackenzie (Nuremberg, Germany).
 
Old 03-21-2012, 12:12 PM
Pandu Poluan
 
Default mdev: sound is only working some of the time.

On Mar 21, 2012 8:07 PM, "Alan Mackenzie" <acm@muc.de> wrote:

>

> On Wed, Mar 21, 2012 at 07:49:02PM +0700, Pandu Poluan wrote:

> > Strange...

>

> > Do you use mdev to handle hotplugs, btw?

>

> You mean, like sticking in a USB stick, or turning my printer on? *Yes, I

> do.

>


No, I mean, did you do :


echo /bin/mdev > /proc/sys/kernel/hotplug


(ensure beforehand that /bin/mdev is a symlink to /bin/busybox)


Rgds,
 
Old 03-21-2012, 12:17 PM
Pandu Poluan
 
Default mdev: sound is only working some of the time.

On Mar 21, 2012 8:07 PM, "Alan Mackenzie" <acm@muc.de> wrote:

>

> On Wed, Mar 21, 2012 at 07:49:02PM +0700, Pandu Poluan wrote:

>

> > Strange...

>

> > Do you use mdev to handle hotplugs, btw?

>

> You mean, like sticking in a USB stick, or turning my printer on? *Yes, I

> do.

>


No, I mean doing this:


echo /bin/mdev > /proc/sys/kernel/hotplug


(ensure beforehand that /bin/mdev is a symlink to /bin/busybox)


Rgds,
 
Old 03-21-2012, 12:38 PM
Alan Mackenzie
 
Default mdev: sound is only working some of the time.

Hello again,

On Wed, Mar 21, 2012 at 08:12:40PM +0700, Pandu Poluan wrote:
> On Mar 21, 2012 8:07 PM, "Alan Mackenzie" <acm@muc.de> wrote:

> > On Wed, Mar 21, 2012 at 07:49:02PM +0700, Pandu Poluan wrote:
> > > Strange...

> > > Do you use mdev to handle hotplugs, btw?

> > You mean, like sticking in a USB stick, or turning my printer on? Yes, I
> > do.


> No, I mean, did you do :

> echo /bin/mdev > /proc/sys/kernel/hotplug

No I haven't. I don't understand at all what this is about. Any chance
of a quick summary?

> (ensure beforehand that /bin/mdev is a symlink to /bin/busybox)

my /sbin/mdev is an indirect symlink to /bin/busybox as follows:
^

/sbin/mdev -> /bin/bb -> busybox

Presumably this would be OK.

> Rgds,

--
Alan Mackenzie (Nuremberg, Germany).
 
Old 03-21-2012, 02:38 PM
Pandu Poluan
 
Default mdev: sound is only working some of the time.

On Mar 21, 2012 10:04 PM, "Alan Mackenzie" <acm@muc.de> wrote:

>

> Hello again,

>

> On Wed, Mar 21, 2012 at 08:12:40PM +0700, Pandu Poluan wrote:

> > On Mar 21, 2012 8:07 PM, "Alan Mackenzie" <acm@muc.de> wrote:

>

> > > On Wed, Mar 21, 2012 at 07:49:02PM +0700, Pandu Poluan wrote:

> > > > Strange...

>

> > > > Do you use mdev to handle hotplugs, btw?

>

> > > You mean, like sticking in a USB stick, or turning my printer on? *Yes, I

> > > do.

>

>

> > No, I mean, did you do :

>

> > echo /bin/mdev > /proc/sys/kernel/hotplug

>

> No I haven't. *I don't understand at all what this is about. *Any chance

> of a quick summary?

>


According to the busybox documentation, /proc/sys/kernel/hotplug contains the path to a program that will be invoked on hotplug events (hotplug here means the creation of a new device node under /dev, not necessarily actually plugging something onto the box).



Doing the above 'echo' will result in kernel invoking mdev when a hotplug event fires; mdev will then act upon the newly-created device node according to the 'recipe' in /etc/mdev.conf, e.g., chown-ing the node, renaming/moving the node, making a symlink, or even triggering a script.



The above line should go right after the 'mdev -s' line in linuxrc.


> > (ensure beforehand that /bin/mdev is a symlink to /bin/busybox)

>

> my /sbin/mdev is an indirect symlink to /bin/busybox as follows:

> * *^

>

> * */sbin/mdev -> /bin/bb -> busybox

>

> Presumably this would be OK.

>


I think so...


Rgds,
 

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