[Q] No message from Kernel (Howto start debug?)

[Q] No message from Kernel (Howto start debug?)

[Arno Steffen]

Maybe you are so kind to give me a hint:

Try to migrate from Kernel 33 to 37. Currently I don't see any message after

  Verifying Checksum ... OK
   Loading Kernel Image ... OK
OK

Starting kernel ...

>From what I understand kernel starts with start_kernel()).
What is best way to find out which part is failing? At which point I
do a printk to see what's going on, or at least set a GPIO Pin of the
processor?
How to debug without any external tools like JTAG.

Re: [Q] No message from Kernel (Howto start debug?)

[Gary Thomas]

On 2011-07-28 07:15, Arno Steffen wrote:
> Maybe you are so kind to give me a hint:
>
> Try to migrate from Kernel 33 to 37. Currently I don't see any message after
>
>    Verifying Checksum ... OK
>     Loading Kernel Image ... OK
> OK
>
> Starting kernel ...
>
>> From what I understand kernel starts with start_kernel()).
> What is best way to find out which part is failing? At which point I
> do a printk to see what's going on, or at least set a GPIO Pin of the
> processor?
> How to debug without any external tools like JTAG.

Start with your bootargs - likely ttyS2 became ttyO2

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

Re: [Q] No message from Kernel (Howto start debug?)

[Felipe Balbi]

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On Thu, Jul 28, 2011 at 03:15:20PM +0200, Arno Steffen wrote:
> Maybe you are so kind to give me a hint:
> 
> Try to migrate from Kernel 33 to 37. Currently I don't see any message after
> 
>   Verifying Checksum ... OK
>    Loading Kernel Image ... OK
> OK
> 
> Starting kernel ...
> 
> From what I understand kernel starts with start_kernel()).
> What is best way to find out which part is failing? At which point I
> do a printk to see what's going on, or at least set a GPIO Pin of the
> processor?
> How to debug without any external tools like JTAG.

try to enable CONFIG_DEBUG_LL and CONFIG_EARLY_PRINTK, then add "debug
earlyprintk" to your command line. See if that helps showing more debug
messages.

-- 
balbi

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Re: [Q] No message from Kernel (Howto start debug?)

[Arno Steffen]

That has been good points. I've tried both, but with no result so far.

boot_nfs_nand=tftpboot 0x80000000 uImage; set bootargs
${bootargs_fs1}; run addip; bootm 0x80000000 ethaddr=00:11:22:33:44:55
bootcmd=run boot_nfs_nand
bootargs=mem=128M console=ttyO2,115200 noinitrd root=/dev/mtdblock6
rootfstype=jffs2
bootargs_fs1=mem=128M console=ttyO2,115200 noinitrd
root=/dev/mtdblock6 rootfstype=jffs2 debug earlyprintk
- Arno


2011/7/28 Felipe Balbi <balbi@ti.com>:
> On Thu, Jul 28, 2011 at 03:15:20PM +0200, Arno Steffen wrote:
>> Maybe you are so kind to give me a hint:
>>
>> Try to migrate from Kernel 33 to 37. Currently I don't see any message after
>>
>>   Verifying Checksum ... OK
>>    Loading Kernel Image ... OK
>> OK
>>
>> Starting kernel ...
>>
>> From what I understand kernel starts with start_kernel()).
>> What is best way to find out which part is failing? At which point I
>> do a printk to see what's going on, or at least set a GPIO Pin of the
>> processor?
>> How to debug without any external tools like JTAG.
>
> try to enable CONFIG_DEBUG_LL and CONFIG_EARLY_PRINTK, then add "debug
> earlyprintk" to your command line. See if that helps showing more debug
> messages.
>
> --
> balbi
>
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Re: [Q] No message from Kernel (Howto start debug?)

[Felipe Balbi]

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Hi,

(please don't top-post)

On Thu, Jul 28, 2011 at 04:18:51PM +0200, Arno Steffen wrote:
> That has been good points. I've tried both, but with no result so far.
> 
> boot_nfs_nand=tftpboot 0x80000000 uImage; set bootargs
> ${bootargs_fs1}; run addip; bootm 0x80000000 ethaddr=00:11:22:33:44:55
> bootcmd=run boot_nfs_nand
> bootargs=mem=128M console=ttyO2,115200 noinitrd root=/dev/mtdblock6
> rootfstype=jffs2
> bootargs_fs1=mem=128M console=ttyO2,115200 noinitrd
> root=/dev/mtdblock6 rootfstype=jffs2 debug earlyprintk

Dumb question, did you recompile your kernel with those enabled ?

If nothing comes out, then you might need the help of a JTAG debugger.
You might want to try openocd though as it's open source and there are
many cheap JTAG debuggers which work with that (Flyswatter,
arm-usb-ocd, arm-usb-ocd-h, etc).

-- 
balbi

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RE: [Q] No message from Kernel (Howto start debug?)

[Sricharan R]

>-----Original Message-----
>From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
>owner@vger.kernel.org] On Behalf Of Arno Steffen
>Sent: Thursday, July 28, 2011 6:45 PM
>To: linux-omap@vger.kernel.org
>Subject: [Q] No message from Kernel (Howto start debug?)
>
>Maybe you are so kind to give me a hint:
>
>Try to migrate from Kernel 33 to 37. Currently I don't see any message
>after
>
>  Verifying Checksum ... OK
>   Loading Kernel Image ... OK
>OK
>
>Starting kernel ...
>
 If you are stuck with Starting kernel ... and do not see
   "Uncompressing Linux... done, booting the kernel" means could have
crashed before your kernel in case of uImage.
 Check the arch_id that you are passing from the bootloader.

Also enable early printk.

>From what I understand kernel starts with start_kernel()).
>What is best way to find out which part is failing? At which point I
>do a printk to see what's going on, or at least set a GPIO Pin of the
>processor?
>How to debug without any external tools like JTAG.
>--
>To unsubscribe from this list: send the line "unsubscribe linux-omap" in
>the body of a message to majordomo@vger.kernel.org
>More majordomo info at  http://vger.kernel.org/majordomo-info.html

Thanks,
 Sricharan

Re: [Q] No message from Kernel (Howto start debug?)

[Arno Steffen]

2011/7/28 Sricharan R <r.sricharan@ti.com>:
>>-----Original Message-----
>>From: Arno Steffen [mailto:arno.steffen@googlemail.com]
>>Sent: Thursday, July 28, 2011 9:13 PM
>>To: Sricharan R
>>Subject: Re: [Q] No message from Kernel (Howto start debug?)
>>
>>2011/7/28 Arno Steffen <arno.steffen@googlemail.com>:
>>> 2011/7/28 Sricharan R <r.sricharan@ti.com>:
>>>>  If you are stuck with Starting kernel ... and do not see
>>>>   "Uncompressing Linux... done, booting the kernel" means could have
>>>> crashed before your kernel in case of uImage.
>>>>  Check the arch_id that you are passing from the bootloader.
>>>>
>>>> Also enable early printk.
>>>>
>>>> >From what I understand kernel starts with start_kernel()).
>>>>>What is best way to find out which part is failing? At which point I
>>>>>do a printk to see what's going on, or at least set a GPIO Pin of the
>>>>>processor?
>>>>>How to debug without any external tools like JTAG.
>>>>>--
>>>>>To unsubscribe from this list: send the line "unsubscribe linux-omap"
> in
>>>>>the body of a message to majordomo@vger.kernel.org
>>>>>More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>
>>>> Thanks,
>>>>  Sricharan
>>>>
>>>
>>> You are absolutly right! The strange thing is, uboot can boot my old
>>> kernel out of NAND flash.
>>> And with the old kernel I can also boot via ethernet. Yepp, probably
>>> the arch-id. I will check this.
>>> Thanks
>>> Arno
>>>
>>
>>To optimistic. :(
>>It seems that I have set the MACHINE_START in a proper way.
>>What can prevent this message in uboot? Why it can uncompressing the
>>old uImages, but not the new one?
>
> Is the uncompressing done by u-boot in your case?
>
> I have seen that the uncompress algorithm is built on
> Top the Image. U-boot simply jumps to that location and
> Rest is taken care by the uncompresser. It also sets up the
> Serial port according to the arch
> and prints " Uncompressing Linux... done, booting the kernel".
>
> The serial port number is used for early prints by kernel.
>
> Also check if your load address passed from u-boot is correct?
>
>>Seems I have to dig into uboot.
>>Thanks
>>-Arno
>

Mh, so it's not a uboot issue. Checking the outputs (see below) are
identical, except Linux version and the new image is a bit smaller.
Where does the uncompressor knows about which serial port to use?

Bytes transferred = 1587592 (183988 hex)
## Booting kernel from Legacy Image at 80000000 ...
   Image Name:   Linux-2.6.37
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    1587528 Bytes =  1.5 MB
   Load Address: 80008000
   Entry Point:  80008000
   Verifying Checksum ... OK
   Loading Kernel Image ... OK
OK

Thanks
-Arno
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Re: [Q] No message from Kernel (Howto start debug?)

[Tapani Utriainen]

On Thu, 28 Jul 2011 16:18:51 +0200
Arno Steffen <arno.steffen@googlemail.com> wrote:

> That has been good points. I've tried both, but with no result so far.
> 

Try appending earlyprintk=${console} to your bootargs (where ${console}
is your console string, e.g. ttyO0,115200n8 )

---
Tapani Utriainen, PhD
Senior Software Engineer
TechNexion Ltd, www.technexion.com

Re: [Q] No message from Kernel (Howto start debug?)

[Arno Steffen]

2011/7/29 Tapani Utriainen <tapani@technexion.com>:
> On Thu, 28 Jul 2011 16:18:51 +0200
> Arno Steffen <arno.steffen@googlemail.com> wrote:
>
>> That has been good points. I've tried both, but with no result so far.
>>
>
> Try appending earlyprintk=${console} to your bootargs (where ${console}
> is your console string, e.g. ttyO0,115200n8 )
>
> ---
> Tapani Utriainen, PhD
> Senior Software Engineer
> TechNexion Ltd, www.technexion.com
>
>

Tried this without a change. I really think this is a machine-id problem.
So although I have done same changes for my board as in my previous 33
kernel, it might be not enough to cover the machine-id. Maybe I can
overule this for test to find out the source of this misbehaviour.
The problem is already before the first debug messages are coming.
Sricharan is right, first the message uncompress has to be printed.
Thanks
- Arno

Re: [Q] No message from Kernel (Howto start debug?)

[Arno Steffen]

2011/7/29 Arno Steffen <arno.steffen@googlemail.com>:
> 2011/7/29 Tapani Utriainen <tapani@technexion.com>:
>> On Thu, 28 Jul 2011 16:18:51 +0200
>> Arno Steffen <arno.steffen@googlemail.com> wrote:
>>
>>> That has been good points. I've tried both, but with no result so far.
>>>
>>
>> Try appending earlyprintk=${console} to your bootargs (where ${console}
>> is your console string, e.g. ttyO0,115200n8 )
>>
>> ---
>> Tapani Utriainen, PhD
>> Senior Software Engineer
>> TechNexion Ltd, www.technexion.com
>>
>>
>
> Tried this without a change. I really think this is a machine-id problem.
> So although I have done same changes for my board as in my previous 33
> kernel, it might be not enough to cover the machine-id. Maybe I can
> overule this for test to find out the source of this misbehaviour.
> The problem is already before the first debug messages are coming.
> Sricharan is right, first the message uncompress has to be printed.
> Thanks
> - Arno
>

Did some test. So with old I can always see the message "Uncompressing
Linux... done, booting the kernel."
Even if machine-id is not match or if bootargs are wrong regarding ttyS/ttyO.
With new kernel I can't see this message. So the question: Is
something changes there in uncompressing?
I am also a bit confused that I get this:

## Booting kernel from Legacy Image at 80000000 ...
   Image Name:   Linux-2.6.33
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    1505256 Bytes = 1.4 MiB
   Load Address: 80008000
   Entry Point:  80008000
   Verifying Checksum ... OK
   Loading Kernel Image ... OK
OK

and the kernel still has to be uncompressed?
- Arno