[ECOS] ARM arch: unknown asm insn "mrc" in v5T_semantics()

Heiko Panther heiko.panther@web.de
Tue Mar 16 14:39:00 GMT 2004


>>I'm targetting an ARM7 TDMI processor, and gcc 3.3.2 complains about 
>>this inline asm instruction from function arm_stub.h:v5T_semantics().
> 
> 
>>     asm volatile ("mrc  p15,0,%0,c0,c0,0\n"
>>		  : "=r" (id) : /* no inputs */);
> 
> 
>>What's up with this insn, I can't find it in the reference. And what 
>>should I correct to make it work?
> 
> 
> Which reference? It is covered in the ARM Architectural Reference Manual.
> The instruction reads the CPU ID register and is valid for all ARM cpus.

My bad, I only looked in the thumb ref card. So that's an ARM 
instruction... I'm compiling with -mthumb. I left away all the 
thumb-interwork flags, since I don't need to integrate any ARM code 
libs. Could that be a problem?

Otherwise, I would probably have to switch to ARM mode before the mrc. 
I'm gonna try that.

Heiko


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