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Re: Booting Kernel on Amiga 3000



On Tue, 6 Sep 2022, Laurent Vivier wrote:

> Le 06/09/2022 à 17:52, Andreas Schwab a écrit :
> > On Sep 06 2022, Eero Tamminen wrote:
> > 
> >> Hi,
> >>
> >> On 6.9.2022 4.46, Stephen Walsh wrote:
> >>> [    3.110000] Call Trace: [<00354d80>] panic+0xc4/0x246
> >>> [    3.110000]  [<00355744>] _printk+0x0/0x18
> >>> [    3.110000]  [<00355756>] _printk+0x12/0x18
> >>> [    3.110000]  [<001ed30c>] strlen+0x0/0x14
> >>> [    3.110000]  [<0051054a>] mount_block_root+0x17a/0x194
> >>> [    3.110000]  [<001ed268>] strncmp+0x0/0x34
> >>> [    3.110000]  [<005105ac>] mount_root+0x48/0x14e
> >>> [    3.110000]  [<005105d6>] mount_root+0x72/0x14e
> >>> [    3.110000]  [<00008001>] atari_get_hardware_list+0x6d/0x3e0
> >>
> >> This seems a bit odd line for kernel boot on Amiga.
> > 
> > It's a false match (0x8001 can be anything).
> > 
> 

Expanding a little on what Andreas said above: Linux/m68k doesn't produce 
precise backtraces. What gets printed is any value found on the stack that 
could possibly be interpreted as an instruction pointer i.e. any address 
within a kernel code segment.

> Stack corruption?
> 

No, i's not an oops, it's normal behaviour:

[    3.110000] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

This expected, and it is not the crash that was originally reported. 

Regarding the oops that was originally reported, the kernel already told 
us why it crashed:

[    0.000000] Ignoring memory chunk at 0x7800000:0x800000 before the first chunk
[    0.000000] Fix your bootloader or use a memfile to make use of this area!

Hence Geert's questions aimed at figuring out what's going on with the 
bootloader.

> 0x8001 looks like
> 
> uapi/asm/bootinfo-amiga.h:#define BI_AMIGA_AUTOCON	0x8001	/* AutoConfig
> device */
> 

By the time the kernel gets to mounting the rootfs, the stack frame 
generated by amiga_parse_bootinfo() has been clobbered many times over.

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