problem with "undefined instruction"

problem with "undefined instruction"

[Sebastian Reichel]

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Hi,

I'm currently trying to get a mainline based kernel running on my pandaboard.
The problem is, that it's crashing very early during the init phase because of
"undefined instruction" exceptions:

[    1.867980] udevd (56): undefined instruction: pc=401e6ed4
[    1.874603] Code: 9cd0 fffe e92d 4ff0 (ed2d)
[    1.977752] modprobe (69): undefined instruction: pc=400c6ed4
[    1.977783] Code: 9cd0 fffe e92d 4ff0 (ed2d)
[    1.978240] init (1): undefined instruction: pc=40149ed4
[    1.978240] Code: 9cd0 fffe e92d 4ff0 (ed2d)
[    2.005706] Kernel panic - not syncing: Attempted to kill init!

Exactly the same userland boots fine with the original 2.6.35 kernel, so it's
probably not the userland's fault. But I searched for the byte combination
anyway and found it in libc.so:

   32ecc:   9cd0        ldr r4, [sp, #832]  ; 0x340
   32ece:   fffe e92d   vtbl.8  d30, {d14-d15}, d29

00032ed0 <_IO_vfprintf>:
   32ed0:   e92d 4ff0   stmdb   sp!, {r4, r5, r6, r7, r8, r9, sl, fp, lr}
   32ed4:   ed2d 8b02   vpush   {d8}

Can you please tell me what's missing in my kernel? I uploaded
.config and full boot messages here:

http://elektranox.org/omap-kernel/config.txt (kernel's .config)
http://elektranox.org/omap-kernel/dmesg.txt (full boot output)

-- Sebastian

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Re: problem with "undefined instruction"

[Santosh Shilimkar]

On 4/30/2011 9:53 PM, Sebastian Reichel wrote:
> Hi,
>
> I'm currently trying to get a mainline based kernel running on my pandaboard.
> The problem is, that it's crashing very early during the init phase because of
> "undefined instruction" exceptions:
>
> [    1.867980] udevd (56): undefined instruction: pc=401e6ed4
> [    1.874603] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> [    1.977752] modprobe (69): undefined instruction: pc=400c6ed4
> [    1.977783] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> [    1.978240] init (1): undefined instruction: pc=40149ed4
> [    1.978240] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> [    2.005706] Kernel panic - not syncing: Attempted to kill init!
>
> Exactly the same userland boots fine with the original 2.6.35 kernel, so it's
> probably not the userland's fault. But I searched for the byte combination
> anyway and found it in libc.so:
>
>     32ecc:   9cd0        ldr r4, [sp, #832]  ; 0x340
>     32ece:   fffe e92d   vtbl.8  d30, {d14-d15}, d29
>
> 00032ed0<_IO_vfprintf>:
>     32ed0:   e92d 4ff0   stmdb   sp!, {r4, r5, r6, r7, r8, r9, sl, fp, lr}
>     32ed4:   ed2d 8b02   vpush   {d8}
>

Looks like NEON instructions are taking an exception. Can you disable
VFP, NEON and give a one more shot.

> Can you please tell me what's missing in my kernel? I uploaded
> .config and full boot messages here:
>
Config seems to enable needed NEON/VFP options.


Regards
Santosh

Re: problem with "undefined instruction"

[Måns Rullgård]

Sebastian Reichel <sre@debian.org> writes:

> Hi,
>
> I'm currently trying to get a mainline based kernel running on my pandaboard.
> The problem is, that it's crashing very early during the init phase because of
> "undefined instruction" exceptions:
>
> [    1.867980] udevd (56): undefined instruction: pc=401e6ed4
> [    1.874603] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> [    1.977752] modprobe (69): undefined instruction: pc=400c6ed4
> [    1.977783] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> [    1.978240] init (1): undefined instruction: pc=40149ed4
> [    1.978240] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> [    2.005706] Kernel panic - not syncing: Attempted to kill init!
>
> Exactly the same userland boots fine with the original 2.6.35 kernel, so it's
> probably not the userland's fault. But I searched for the byte combination
> anyway and found it in libc.so:
>
>    32ecc:   9cd0        ldr r4, [sp, #832]  ; 0x340
>    32ece:   fffe e92d   vtbl.8  d30, {d14-d15}, d29
>
> 00032ed0 <_IO_vfprintf>:
>    32ed0:   e92d 4ff0   stmdb   sp!, {r4, r5, r6, r7, r8, r9, sl, fp, lr}
>    32ed4:   ed2d 8b02   vpush   {d8}

Your userland appears to be built with Thumb2.  Make sure CONFIG_THUMB
is enabled in your kernel.

-- 
Måns Rullgård
mans@mansr.com

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Re: problem with "undefined instruction"

[Santosh Shilimkar]

On 4/30/2011 10:14 PM, Måns Rullgård wrote:
> Sebastian Reichel<sre@debian.org>  writes:
>

[..]

>>
>>     32ecc:   9cd0        ldr r4, [sp, #832]  ; 0x340
>>     32ece:   fffe e92d   vtbl.8  d30, {d14-d15}, d29
>>
>> 00032ed0<_IO_vfprintf>:
>>     32ed0:   e92d 4ff0   stmdb   sp!, {r4, r5, r6, r7, r8, r9, sl, fp, lr}
>>     32ed4:   ed2d 8b02   vpush   {d8}
>
> Your userland appears to be built with Thumb2.  Make sure CONFIG_THUMB
> is enabled in your kernel.
>
Oh yes. The config has CONFIG_ARM_THUMB=y but THUMB2 isn't enabled.

CONFIG_THUMB2_KERNEL=y should fix the problem.

Regards
Santosh



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Re: problem with "undefined instruction"

[Måns Rullgård]

Santosh Shilimkar <santosh.shilimkar@ti.com> writes:

> On 4/30/2011 10:14 PM, Måns Rullgård wrote:
>> Sebastian Reichel<sre@debian.org>  writes:
>>
>
> [..]
>
>>>
>>>     32ecc:   9cd0        ldr r4, [sp, #832]  ; 0x340
>>>     32ece:   fffe e92d   vtbl.8  d30, {d14-d15}, d29
>>>
>>> 00032ed0<_IO_vfprintf>:
>>>     32ed0:   e92d 4ff0   stmdb   sp!, {r4, r5, r6, r7, r8, r9, sl, fp, lr}
>>>     32ed4:   ed2d 8b02   vpush   {d8}
>>
>> Your userland appears to be built with Thumb2.  Make sure CONFIG_THUMB
>> is enabled in your kernel.
>>
> Oh yes. The config has CONFIG_ARM_THUMB=y but THUMB2 isn't enabled.

Sorry, I meant CONFIG_ARM_THUMB and that is indeed enabled.  Must be
something else.

> CONFIG_THUMB2_KERNEL=y should fix the problem.

No, that builds the kernel in Thumb2 mode and you probably don't want
that.

-- 
Måns Rullgård
mans@mansr.com

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Re: problem with "undefined instruction"

[Sebastian Reichel]

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On Sat, Apr 30, 2011 at 06:23:57PM +0200, Sebastian Reichel wrote:
> I'm currently trying to get a mainline based kernel running on my pandaboard.
> The problem is, that it's crashing very early during the init phase because of
> "undefined instruction" exceptions:
> 
> [    1.867980] udevd (56): undefined instruction: pc=401e6ed4
> [    1.874603] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> [    1.977752] modprobe (69): undefined instruction: pc=400c6ed4
> [    1.977783] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> [    1.978240] init (1): undefined instruction: pc=40149ed4
> [    1.978240] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> [    2.005706] Kernel panic - not syncing: Attempted to kill init!
>
> Exactly the same userland boots fine with the original 2.6.35 kernel, so it's
> probably not the userland's fault.

I found the source of this problem. VFPv3 support is not working
correctly when OMAP2 (and thus CPU_V6) is enabled in the kernel
config.

I guess this should be mentioned in the kernel config (or fixed if
possible).

-- Sebastian

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Re: problem with "undefined instruction"

[Tony Lindgren]

* Sebastian Reichel <sre@debian.org> [110606 15:51]:
> On Sat, Apr 30, 2011 at 06:23:57PM +0200, Sebastian Reichel wrote:
> > I'm currently trying to get a mainline based kernel running on my pandaboard.
> > The problem is, that it's crashing very early during the init phase because of
> > "undefined instruction" exceptions:
> > 
> > [    1.867980] udevd (56): undefined instruction: pc=401e6ed4
> > [    1.874603] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> > [    1.977752] modprobe (69): undefined instruction: pc=400c6ed4
> > [    1.977783] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> > [    1.978240] init (1): undefined instruction: pc=40149ed4
> > [    1.978240] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> > [    2.005706] Kernel panic - not syncing: Attempted to kill init!
> >
> > Exactly the same userland boots fine with the original 2.6.35 kernel, so it's
> > probably not the userland's fault.
> 
> I found the source of this problem. VFPv3 support is not working
> correctly when OMAP2 (and thus CPU_V6) is enabled in the kernel
> config.
> 
> I guess this should be mentioned in the kernel config (or fixed if
> possible).

This should be easy to fix now. Do you have a minimal test program that
triggers this?

Tony

Re: problem with "undefined instruction"

[Sebastian Reichel]

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On Tue, Jun 07, 2011 at 02:53:31PM +0300, Tony Lindgren wrote:
> * Sebastian Reichel <sre@debian.org> [110606 15:51]:
> > On Sat, Apr 30, 2011 at 06:23:57PM +0200, Sebastian Reichel wrote:
> > > I'm currently trying to get a mainline based kernel running on my pandaboard.
> > > The problem is, that it's crashing very early during the init phase because of
> > > "undefined instruction" exceptions:
> > > 
> > > [    1.867980] udevd (56): undefined instruction: pc=401e6ed4
> > > [    1.874603] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> > > [    1.977752] modprobe (69): undefined instruction: pc=400c6ed4
> > > [    1.977783] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> > > [    1.978240] init (1): undefined instruction: pc=40149ed4
> > > [    1.978240] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> > > [    2.005706] Kernel panic - not syncing: Attempted to kill init!
> > >
> > > Exactly the same userland boots fine with the original 2.6.35 kernel, so it's
> > > probably not the userland's fault.
> > 
> > I found the source of this problem. VFPv3 support is not working
> > correctly when OMAP2 (and thus CPU_V6) is enabled in the kernel
> > config.
> > 
> > I guess this should be mentioned in the kernel config (or fixed if
> > possible).
> 
> This should be easy to fix now. Do you have a minimal test program that
> triggers this?

Sorry for the delay, here is a minimal test binary, that triggers
the bug: http://elektranox.org/omap-kernel/test

-- Sebastian

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Re: problem with "undefined instruction"

[Tony Lindgren]

* Sebastian Reichel <sre@debian.org> [110623 12:49]:
> On Tue, Jun 07, 2011 at 02:53:31PM +0300, Tony Lindgren wrote:
> > * Sebastian Reichel <sre@debian.org> [110606 15:51]:
> > > On Sat, Apr 30, 2011 at 06:23:57PM +0200, Sebastian Reichel wrote:
> > > > I'm currently trying to get a mainline based kernel running on my pandaboard.
> > > > The problem is, that it's crashing very early during the init phase because of
> > > > "undefined instruction" exceptions:
> > > > 
> > > > [    1.867980] udevd (56): undefined instruction: pc=401e6ed4
> > > > [    1.874603] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> > > > [    1.977752] modprobe (69): undefined instruction: pc=400c6ed4
> > > > [    1.977783] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> > > > [    1.978240] init (1): undefined instruction: pc=40149ed4
> > > > [    1.978240] Code: 9cd0 fffe e92d 4ff0 (ed2d)
> > > > [    2.005706] Kernel panic - not syncing: Attempted to kill init!
> > > >
> > > > Exactly the same userland boots fine with the original 2.6.35 kernel, so it's
> > > > probably not the userland's fault.
> > > 
> > > I found the source of this problem. VFPv3 support is not working
> > > correctly when OMAP2 (and thus CPU_V6) is enabled in the kernel
> > > config.
> > > 
> > > I guess this should be mentioned in the kernel config (or fixed if
> > > possible).
> > 
> > This should be easy to fix now. Do you have a minimal test program that
> > triggers this?
> 
> Sorry for the delay, here is a minimal test binary, that triggers
> the bug: http://elektranox.org/omap-kernel/test

Heh that's pretty minimal :) I'll take a look why it fails.

Tony