[uClinux-dev] ARM7TDMI zImage booting

Daniel Glöckner daniel-gl at gmx.net
Sat Jul 27 12:26:57 EDT 2013


Hi Tobias,

On Sat, Jul 27, 2013 at 02:53:07PM +0000, Plüss Tobias TA.E.1001 wrote:
> >> CONFIG_PROCESSOR_ID
> 
> MANY THANKS for this tip! I have never analysed what this processor ID is
> used for; i always thought that it is just some arbitrary number to verify
> that the kernel is running on the right hardware. So I left it always at
> the default value, which is 0x41007700. But, now I searched in the head.S
> file for this number, and you we're right - it seems like this is the
> processor ID for ARM7/710, which is definitely wrong. I'll try this
> evening to change the CONFIG_PROCESSOR_ID to 0x00020000, which should be
> ARMv4T - which is exactly what I want. I'll tell you whether I'm
> successful ;-)

0x41007700 won't lead to clz, though, and ARM7/710 doesn't sound wrong
for an ARM7TDMI. If the support for other processors is still enabled,
head.S will ask CP15 for the ID. A plain ARM7TDMI doesn't have that
coprocessor and will most likey generate an exception. Do you have
CONFIG_CPU_CP15=y in your .config?

  Daniel


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