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Tom Cook | 25 Jun 2012 17:17

Debugging kernel lockups

Hi,

Sorry for asking newbie questions here, but I'm, well, a newbie at
this.  I'm trying to get the 3.2.20-rt32 patch to boot on a Raspberry
Pi, but it seems the patch breaks the SD/MMC card driver and so the
root filesystem can't be mounted.  I've built a 3.2.20 source tree and
it boots fine, then I apply 3.2.20-rt32 patch and the boot halts
trying to find the SD card for the root FS.

I'm not too worried about trying to debug / fix this, but I don't
really know where to start.  Can someone give me some pointers towards
how to track this sort of thing down?  Is kdb the right tool for the
job?

Thanks,
Tom
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Sven-Thorsten Dietrich | 25 Jun 2012 18:52

Re: Debugging kernel lockups


On Jun 25, 2012, at 8:17 AM, Tom Cook wrote:

> Hi,
> 
> Sorry for asking newbie questions here, but I'm, well, a newbie at
> this.  I'm trying to get the 3.2.20-rt32 patch to boot on a Raspberry
> Pi, but it seems the patch breaks the SD/MMC card driver and so the
> root filesystem can't be mounted.  I've built a 3.2.20 source tree and
> it boots fine, then I apply 3.2.20-rt32 patch and the boot halts
> trying to find the SD card for the root FS.
> 
> I'm not too worried about trying to debug / fix this, but I don't
> really know where to start.  Can someone give me some pointers towards
> how to track this sort of thing down?  Is kdb the right tool for the
> job?

Can you capture a serial console log of the boot process?

Thanks

Sven
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Tom Cook | 26 Jun 2012 00:08

Re: Debugging kernel lockups

On Mon, Jun 25, 2012 at 5:52 PM, Sven-Thorsten Dietrich
<sven <at> thebigcorporation.com> wrote:
> On Jun 25, 2012, at 8:17 AM, Tom Cook wrote:
[snip]
>
> Can you capture a serial console log of the boot process?
>
> Thanks
>
> Sven

Maybe.  The board's UART comes out through a header, and I should get
the bits delivered tomorrow to build this into a usable RS-232
connection.

Regards,
Tom
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richard -rw- weinberger | 25 Jun 2012 23:15

Re: Debugging kernel lockups

On Mon, Jun 25, 2012 at 5:17 PM, Tom Cook <tom.k.cook <at> gmail.com> wrote:
> Hi,
>
> Sorry for asking newbie questions here, but I'm, well, a newbie at
> this.  I'm trying to get the 3.2.20-rt32 patch to boot on a Raspberry
> Pi, but it seems the patch breaks the SD/MMC card driver and so the
> root filesystem can't be mounted.  I've built a 3.2.20 source tree and
> it boots fine, then I apply 3.2.20-rt32 patch and the boot halts
> trying to find the SD card for the root FS.

You can try the "rootwait" kernel parameter.
But as Sven said, the boot log would be nice to have.

--

-- 
Thanks,
//richard
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