MPC555 : wrong assembly instruction with GCC

Sergei Organov osv at
Mon Apr 29 16:00:46 UTC 2002

It's not gcc. I believe gcc knows nothing about cache.

Take a look at macro call

_CPU_Data_Cache_Block_Flush( slot );

at the end of the routine -- it's definition contains explicit asm statement
containing 'dcbf' instruction.


SMIALEK Yan <Yan.SMIALEK at> writes:
> Hello,
> I managed to compile a program for a MPC555 with GCC and I use SingleStep
> from WindRiver to debug it.
> But, GCC creates an illegal assembly instruction in the cpu.s file (from
> cpu.c file), at the end of function _CPU_ISR_install_raw_handler .
> This instruction is " dcbf "  and is about the cache memory.
> Unfortunately, the MPC555 doesn't have any instructions or data cache memory
> !   :-(
> I suppose this problem comes from GCC (maybe the mcpu option). 
> I tried the mcpu option with powerpc, power, power2, 603, 505 .... But I
> can't find a similar processor with no cache memory for this option.
> Does anyone has an idea for this error ?
> Thank you !
> Yan

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