Re: Kernel Image Format Issue - Coldfire mcf54418 CPU Failing to Boot

[Greg Ungerer <gerg@linux-m68k.org>]

Hi Jean-Michel,


On 15/5/24 17:56, Jean-Michel Hautbois wrote:
> Hi Michael,
> 
> 
> On 14/05/2024 22:16, Michael Schmitz wrote:
>> Jean-Michel,
>>
>> 'BIV' is probably a bootinfo tag (Boot Info Version).
> 
> Thanks, it helped me, as I read the head.S file and finally progressed :-).
> 
> When dumping my vmlinux, I can see the entry point is *not* the load 
> address (it was in the old one):
> vmlinux:     file format elf32-m68k
> 
> 
> Disassembly of section .text:
> 
> 40001000 <_stext>:
> 40001000:    4ef9 4000 2000     jmp 40002000 <_start>
>      ...
> 
> 40002000 <_start>:
> 40002000:    4e71               nop
> 40002002:    46fc 2700          movew #9984,%sr
> 40002006:    203c 0104 0100     movel #17039616,%d0
> 4000200c:    4e7b 0002          movec %d0,%cacr
> 40002010:    4e71               nop
> 
> Now, when uboot starts the kernel, it is not doing anything (not sure if 
> it hangs or does not display anything on the console. And EARLY_PRINTK 
> is not valid for coldfire :-(. Not sure why, so any guidance here would 
> be appreciate too !
> 
> I will now check my platform file but at least I am not trying to 
> execute an instruction "0" :-).

Can you post your kernel .conig file?
Did you just start with your original 3.0.12 config and use that for 6.1.83?

Regards
Greg



> Thanks,
> JM
> 
>>
>> Cheers,
>>
>>      Michael
>>
>> On 15/05/24 07:11, Jean-Michel Hautbois wrote:
>>> Hello,
>>>
>>> I have been on this for a long time now, and I think it is time to 
>>> ask for some help as the answer might be "easy" :-).
>>>
>>> I'm trying to boot an upstream Linux kernel (version 6.1.83 from CIP) 
>>> on a custom board which already runs an old one (3.0.12).
>>>
>>> I'm encountering an issue where the CPU fails to boot with an 
>>> "Unexpected exception" error when u-boot calls bootm.
>>>
>>> -> bootm
>>> ## Booting kernel from Legacy Image at 41000000 ...
>>>    Image Name:   Linux-6.1.83-cip18-rt10
>>>    Created:      2024-04-17   5:42:32 UTC
>>>    Image Type:   M68K Linux Kernel Image (uncompressed)
>>>    Data Size:    5684872 Bytes =  5.4 MB
>>>    Load Address: 40001000
>>>    Entry Point:  40001000
>>>    Checksum:  6bc7660a
>>>    Verifying Checksum ... OK
>>>    Loading Kernel Image ... OK
>>> OK
>>>
>>>
>>> *** Unexpected exception ***
>>> Vector Number: 5  Format: 04  Fault Status: 0
>>>
>>> PC: 40001002    SR: 00002700    SP: 4fd5fcdc
>>> D0: 00000000    D1: 00000003    D2: 4fdfa71c    D3: 00000000
>>> D4: 00000000    D5: 00000001    D6: 00000000    D7: 00000001
>>> A0: 00000000    A1: 4fd71494    A2: 40001000    A3: 4fdfa690
>>> A4: 4fd91b30    A5: 4fdf3600    A6: 4fd5fd64
>>>
>>> *** Please Reset Board! ***
>>>
>>> I tried to use different Load and Entry adress but this is not having 
>>> any effect.
>>>
>>> Sadly, I can't use the (very) old toolchain to build my kernel, and I 
>>> can't build the old kernel with the toolchain I generated. It has 
>>> been done with buildroot and I can provide some information if this 
>>> is relevant.
>>> To summarize:
>>> - It has MMU enabled
>>> - The cpu is passed with -mcpu=54418
>>> - The architecture is passed with -march=isac
>>>
>>> As the u-boot version I have can't be updated (at least not easily) I 
>>> need to provide a uImage, so I call mkimage for this when the vmlinux 
>>> file is generated.
>>>
>>> I've compared the kernel image format with an older working kernel 
>>> image, and it seems the issue is related to the kernel image format.
>>>
>>> ```
>>> $> hexdump -C uImage-3.0.12 |head
>>> 00000000  27 05 19 56 c6 4d 40 59  62 ac 6a be 00 2f a2 00 
>>> |'..V.M@Yb.j../..|
>>> 00000010  40 02 00 00 40 02 00 00  74 e8 ca f4 05 0c 02 00 
>>> |@...@...t.......|
>>> 00000020  4c 69 6e 75 78 2d 33 2e  30 2e 31 32 2d 72 74 33 
>>> |Linux-3.0.12-rt3|
>>> 00000030  33 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00 
>>> |3...............|
>>> 00000040  60 08 42 49 56 1a 00 00  00 00 4e f9 40 30 20 00 
>>> |`.BIV.....N.@0 .|
>>> 00000050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00 
>>> |................|
>>> *
>>> 00001040  4e f9 40 30 20 00 4e 56  00 00 9f fc 00 00 00 04  |N.@0 
>>> .NV........|
>>> 00001050  48 d7 00 01 20 2f 00 0c  4e 7b 00 03 4c d7 00 01  |H... 
>>> /..N{..L...|
>>> 00001060  df fc 00 00 00 04 4e 5e  4e 75 00 00 4e 75 4e 75 
>>> |......N^Nu..NuNu|
>>> ```
>>>
>>> ```
>>> hexdump -C output/images/uImage |head
>>> 00000000  27 05 19 56 ab 1d 06 74  66 1f 61 48 00 56 be 88 
>>> |'..V...tf.aH.V..|
>>> 00000010  40 00 10 00 40 00 10 00  6b c7 66 0a 05 0c 02 00 
>>> |@...@...k.f.....|
>>> 00000020  4c 69 6e 75 78 2d 36 2e  31 2e 38 33 2d 63 69 70 
>>> |Linux-6.1.83-cip|
>>> 00000030  31 38 2d 72 74 31 30 00  00 00 00 00 00 00 00 00 
>>> |18-rt10.........|
>>> 00000040  7f 45 4c 46 01 02 01 00  00 00 00 00 00 00 00 00 
>>> |.ELF............|
>>> 00000050  00 02 00 04 00 00 00 01  40 00 20 00 00 00 00 34 
>>> |........@. ....4|
>>> 00000060  00 56 bb b8 00 00 00 26  00 34 00 20 00 04 00 28 
>>> |.V.....&.4. ...(|
>>> 00000070  00 12 00 11 00 00 00 01  00 00 00 00 40 00 00 00 
>>> |............@...|
>>> 00000080  40 00 00 00 00 39 d3 d0  00 39 d3 d0 00 00 00 05 
>>> |@....9...9......|
>>> 00000090  00 00 20 00 00 00 00 01  00 39 e0 00 40 39 e0 00  |.. 
>>> ......9..@9..|
>>> ```
>>>
>>> I am a bit surprised by the information at offset 0x40. My kernel is 
>>> an ELF file, but the old one is a BIV file I don't even know what it 
>>> can be -_- !
>>>
>>> I'm happy to provide any additional information or details that might 
>>> be helpful in resolving this issue.
>>>
>>> Thanks in advance for any help !
>>> JM
>>>
>>>
>