Hotplug *seems* to hang during boot]

Hotplug *seems* to hang during boot]

[Richard Wild]

Hi all,

please note the emphasis on *seems*.  I am not claiming there is a 
problem with hotplug.  I think it's just that I have some problem, and 
it manifests itself when hotplug starts up.  Also, none of my usual 
channels for getting help have yielded any useful advice, and I have run 
out of places to turn.  To get to the point, what happens is: when the 
kernel boots up, it gets as far as:

Starting PCMCIA services:
 <Probing for PCIC: edit /etc/rc.d/rc.pcmcia>
cardmgr[953]: no sockets found!
Activating hardware detection: /etc/rc.d/rc.hotplug start

and that's all she writes.  The computer just remains hung, apparently 
starting up hotplug.  This is with a 2.6.7 kernel from my Slackware 10 
installation.  If I use the default 2.4.26 kernel then it starts up OK.

I haven't been able to get any help with this problem anywhere else, so 
I am fervently hoping that someone here will be able to give me some 
advice on what things to try/investigate.

Some other information noticed: it seems (to me) quite likely that the 
message "cardmgr[953]: no sockets found!" is related to the problem, 
because when I boot the 2.4 kernel is says instead "cardmgr[80]: no 
pcmcia driver in /proc/devices".  (This seems reasonable since it's a 
desktop PC).

Another thing is, I can boot the 2.6 kernel if I give it the option 
"nohotplug", however, if I do this then the network controller is 
inoperative.  (According to lspci it is an NVidia NForce2 ethernet 
controller).  This is not an acceptable workaround.

Please let me know if there's any other information I should supply, and 
also thanks very much for your time.

Richard.

P.S. I sent this message twice because the first time it did not seem
to make it to the list.  Perhaps I sent it too soon after subscribing.
If I have erred please accept my apologies.



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Re: Hotplug *seems* to hang during boot]

[Dave Dodge]

On Mon, Oct 04, 2004 at 07:14:07PM +0000, Richard Wild wrote:
> Some other information noticed: it seems (to me) quite likely that the 
> message "cardmgr[953]: no sockets found!" is related to the problem, 
> because when I boot the 2.4 kernel is says instead "cardmgr[80]: no 
> pcmcia driver in /proc/devices".

cardmgr is a bit strange in how it accesses devices.  Here's a quick
explanation in case it's relevant to the problem.

"no pcmcia driver in /proc/devices":

That means just what it says.  cardmgr wants the major device number for
the pcmcia driver, so it reads through /proc/devices looking for it.
This error message indicates that it did not find a "pcmcia" line,
presumably because no driver was loaded.

"no sockets found!":

This indicates that it _did_ find "pcmcia" listed in /proc/devices,
and it tried to access the driver.  Here's where things get a bit
unusual.  After obtaining the major device number from /proc/devices,
cardmgr uses mknod(2) to create device files of its own.  It starts
with minor device 0 and continues in a one-up loop until it fails.
For each minor number, it creates a device file with a name of the
form "cm-PID-COUNTER", opens the file, and then immediately unlinks
the file while holding it open.  There are a number of directories
where it might try to do this, usually in this order:

  /var/lib/pcmcia, /var/run, /dev, /tmp

The "no sockets found" message indicates that it managed to do the
mknod for minor device 0, but got an ENODEV when it then tried to open
the resulting file.

So what this seems to be saying is that:

  - your 2.4 kernel has no PCMCIA stuff loaded at all.

  - your 2.6 kernel has at least the "ds" driver, which
    creates the "pcmcia" /proc/devices entry, but it has no
    card sockets.

I don't know if this is part of your problem or not, but since cardmgr
does do some device file manipulation, it might be worth investigating.

                                                  -Dave Dodge


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Re: Hotplug *seems* to hang during boot]

[Richard Wild]

Hi Dave,

thanks for your reply. Reading it made me think that the first thing to 
try should be to recompile the 2.6.7 kernel with no PCMCIA support at 
all. This is duly did, and when I attempted to boot the kernel cardmgr 
reported that there was no pcmcia driver in /proc/devices as your 
message suggested.

Unfortunately, hotplug still did not start. Whatever the problem is, 
that wasn't it.

Interestingly, I tried booting the 2.6 kernel with "nohotplug" as an 
option; this enabled it to boot as I said earlier (but with no NIC 
function). I then decided to run "/etc/rc.d/rc.hotplug start" to see 
what would happen. It did not merely block as I expected but completely 
locked up the system: mouse, keyboard, no interrupts working at all as 
far as I could see.

I hate to be a luser but I am quite stuck here. I'll do whatever 
investigation is necessary but I could really use some advice on where 
to start.

Thanks,
Rich.

Dave Dodge wrote:

>On Mon, Oct 04, 2004 at 07:14:07PM +0000, Richard Wild wrote:
>  
>
>>Some other information noticed: it seems (to me) quite likely that the 
>>message "cardmgr[953]: no sockets found!" is related to the problem, 
>>because when I boot the 2.4 kernel is says instead "cardmgr[80]: no 
>>pcmcia driver in /proc/devices".
>>    
>>
>
>cardmgr is a bit strange in how it accesses devices.  Here's a quick
>explanation in case it's relevant to the problem.
>
>"no pcmcia driver in /proc/devices":
>
>That means just what it says.  cardmgr wants the major device number for
>the pcmcia driver, so it reads through /proc/devices looking for it.
>This error message indicates that it did not find a "pcmcia" line,
>presumably because no driver was loaded.
>
>"no sockets found!":
>
>This indicates that it _did_ find "pcmcia" listed in /proc/devices,
>and it tried to access the driver.  Here's where things get a bit
>unusual.  After obtaining the major device number from /proc/devices,
>cardmgr uses mknod(2) to create device files of its own.  It starts
>with minor device 0 and continues in a one-up loop until it fails.
>For each minor number, it creates a device file with a name of the
>form "cm-PID-COUNTER", opens the file, and then immediately unlinks
>the file while holding it open.  There are a number of directories
>where it might try to do this, usually in this order:
>
>  /var/lib/pcmcia, /var/run, /dev, /tmp
>
>The "no sockets found" message indicates that it managed to do the
>mknod for minor device 0, but got an ENODEV when it then tried to open
>the resulting file.
>
>So what this seems to be saying is that:
>
>  - your 2.4 kernel has no PCMCIA stuff loaded at all.
>
>  - your 2.6 kernel has at least the "ds" driver, which
>    creates the "pcmcia" /proc/devices entry, but it has no
>    card sockets.
>
>I don't know if this is part of your problem or not, but since cardmgr
>does do some device file manipulation, it might be worth investigating.
>
>                                                  -Dave Dodge
>
>
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>  
>



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Re: Hotplug *seems* to hang during boot]

[Simone Gotti]

[-- Attachment #1: Type: text/plain, Size: 1708 bytes --]

On Monday 04 October 2004 23:32, Richard Wild wrote:
> Hi Dave,
>
> thanks for your reply. Reading it made me think that the first thing to
> try should be to recompile the 2.6.7 kernel with no PCMCIA support at
> all. This is duly did, and when I attempted to boot the kernel cardmgr
> reported that there was no pcmcia driver in /proc/devices as your
> message suggested.
>
> Unfortunately, hotplug still did not start. Whatever the problem is,
> that wasn't it.
>
> Interestingly, I tried booting the 2.6 kernel with "nohotplug" as an
> option; this enabled it to boot as I said earlier (but with no NIC
> function). I then decided to run "/etc/rc.d/rc.hotplug start" to see
> what would happen. It did not merely block as I expected but completely
> locked up the system: mouse, keyboard, no interrupts working at all as
> far as I could see.
>
> I hate to be a luser but I am quite stuck here. I'll do whatever
> investigation is necessary but I could really use some advice on where
> to start.
>
> Thanks,
> Rich.

You can try editing the /etc/hotplug/hotplug.functions and uncomment the line
# DEBUG=yes; export DEBUG

so you can at least see in which part or on which module it's blocking. and if 
it's a kernel problem.

P.S. I don't use slackware from a lot of time, but I thing that you can look 
if you are using the latest hotplug (20040923) or install it.
If this don't work you can also try to apply the patches that you can find in 
debian (I hope to have time to dig in them and send them splitted to this 
list, so also the gentoo's and other distro users can use them).

Bye!
-- 
Simone Gotti
<simone.gotti@email.it>
http://kde-bluetooth.sf.net

[-- Attachment #2: Type: application/pgp-signature, Size: 190 bytes --]

Re: Hotplug *seems* to hang during boot]

[Richard Wild]

Hi,

I had that thought myself immediately after posting.  I went through the 
various scripts putting echo statements in and eventually arrived at 
/etc/hotplug/pci.agent with the line:

    load_drivers pci $MAP_CURRENT "$LABEL"

which expands to:

    load_drivers pci /lib/modules/2.6.7/modules.pcimap PCI slot

That's where it seems to go off the trolley.  I will post more if and 
when I find it.

Thanks,
Rich.

Simone Gotti wrote:

> You can try editing the /etc/hotplug/hotplug.functions and uncomment 
> the line
>
># DEBUG=yes; export DEBUG
>
>so you can at least see in which part or on which module it's blocking. and if 
>it's a kernel problem.
>
>P.S. I don't use slackware from a lot of time, but I thing that you can look 
>if you are using the latest hotplug (20040923) or install it.
>If this don't work you can also try to apply the patches that you can find in 
>debian (I hope to have time to dig in them and send them splitted to this 
>list, so also the gentoo's and other distro users can use them).
>
>Bye!
>  
>



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