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wrote the inline assembler in the C code:
void outl(unsigned short port,unsigned long vaule)
{
__asm__ __volatile__ ( "outl %0,%w1" ::"a"(vaule),"d"(port));
}
But issue error when it's compiled.
that prompted, %0 refers "rax".
But the outl instruction only refers 32bit register.
I can modify "outl %0,%w1" to "outl %%eax,%w1".

But I hope use other way to fix it, just like %0 to use the input parameters.
Thanks

OUTs (and INs) only works with al/ax/eax and dx/constant as its operands. Having GCC choose the registers will only give you trouble since instead of the few options that are actually legal, it may choose practically everything.

Thanks
Do you mean that I must use the "%%eax" to fix it?