[uClinux-dev] CONFIG_ROMFS_FS and MCF532x

[Greg Ungerer]

Hi Wolfgang,

Wolfgang Wegner wrote:
> I just found another thing I am a bit confused about. I am using MCF532x
> target (actually MCF5373L, but apart from few peripherals this is the same)
> and just had some strange kernel startup failures with the linux-2.6.x kernel
> of uClinux-dist-20071107.
> 
> I found that the kernel always got stuck in _copy_romfs in
> linux-2.6.x/arch/m68knommu/platform/5307/head.S
> There is some block of code that seems to handle something like an
> initial ROMFS that is included when CONFIG_ROMFS_FS is set.
> 
> However, CONFIG_ROMFS_FS is already needed for mounting a "normal"
> ROMFS on an MTD device and thus not necessarily means there is something
> like a filesystem (as my assembler knowledge is quite poor I do not
> even claim to understand where the "from"-address for copying comes
> from...).
> 
> So the question is:
> - is there some other config option needed that should be evaluated here?

This is due to the almost universal way that images are put
together on ColdFire. The single image file (which is a kernel
and filesystem concatenated) means that the fs needs to be copied
at kernel start to a more suitable place. And this is the
code you are seeing above, _copy_romfs.

Arguably this should be a configurable option, since just
having a ROMfs fileystem enabled in the kernel doesn't mean that
one is actually appended and loaded after the kernel itself
at runtime.


> - or is there some memory initialization needed that my bootloader (U-Boot)
>   should perform in order for this "initial ROMFS" to be skipped?

No, it wouldn't be uboot that needs to change.

What is the format of the image that you load with uboot?
I assume it is not the usual kernel+filesystem image.bin?

Sounds like you should conditional out the code in the
startup head.S, if your image format is different.
(Say if you are loading the kernel and romfs/ramdisk
as 2 separate files/loads).

Regards
Greg


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Greg Ungerer  --  Chief Software Dude       EMAIL:     gerg at snapgear.com
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