Newbie debugging question

Newbie debugging question

[Richard Stevens]

Hi,

I've been searching the net for quite some time now without success so I 
decided to ask the professionals. I'm looking for kernelhacker newbie 
friendly documentation on how to figure out a little more about a kernel 
lockup to be able to give the developer of a device driver some more info. 
The problem is that after a while the machine locks up with Caps Lock and 
Scroll lock blinking. I don't see any logs and no messages on the console. I 
found some posts describing similar events and it was said that the kernel is 
not completely dead in this state. Is there a way to get some more 
information? Where should I start reading.

Please CC me since I'm not subscribed. 

Thanks,

Richard

Re: Newbie debugging question

[Randy.Dunlap]

> Hi,
>
> I've been searching the net for quite some time now without success so I
> decided to ask the professionals. I'm looking for kernelhacker newbie
> friendly documentation on how to figure out a little more about a kernel
> lockup to be able to give the developer of a device driver some more info.

I suggest asking on the kernelnewbies mailing list (see kernelnewbies.org).
Also, some people started on this web page, but it's only a beginning:
  http://lse.sourceforge.net/debugging/

> The problem is that after a while the machine locks up with Caps Lock and
> Scroll lock blinking. I don't see any logs and no messages on the console. I
>  found some posts describing similar events and it was said that the kernel
> is  not completely dead in this state. Is there a way to get some more
> information? Where should I start reading.
>
> Please CC me since I'm not subscribed.

What kernel version?  That would have some effects on the answer.

Serial console is the usual option/route.  If it boots completely,
you could also try netconsole (or, dare I say it, usb console).
Or LKCD (lkcd.sf.net), or kmsgdump (2.5.75/2.6.0 at
http://www.xenotime.net/linux/kmsgdump/2.5.75/).

~Randy

Re: Newbie debugging question

[Richard Stevens]

Hi,


> I suggest asking on the kernelnewbies mailing list (see kernelnewbies.org).
> Also, some people started on this web page, but it's only a beginning:
>   http://lse.sourceforge.net/debugging/

thanks for the info. I'll do that. 

> What kernel version?  That would have some effects on the answer.

2.4.21 vanilla (now with the latest version of sgi's kdb)

>
> Serial console is the usual option/route.  If it boots completely,
> you could also try netconsole (or, dare I say it, usb console).
> Or LKCD (lkcd.sf.net), or kmsgdump (2.5.75/2.6.0 at
> http://www.xenotime.net/linux/kmsgdump/2.5.75/).

I'll check these. I managed to get some information via kdb and serial 
console. Don't know if it is useful but I guess they will tell me :-)

Thanks again,

Richard


PS: In case of answers to this, please CC me since I'm not subscribed.