Re: [Qemu-devel] [PATCH V8 2/7] nios2: Add architecture emulation support

[Sandra Loosemore]

On 01/16/2017 03:21 PM, Alexander Graf wrote:

> > +static void nios2_cpu_disas_set_info(CPUState *cpu, disassemble_info
> > *info)
> > +{
> > +    /* NOTE: NiosII R2 is not supported yet. */
> > +    info->mach = bfd_arch_nios2;
> > +#ifdef TARGET_WORDS_BIGENDIAN
> > +    info->print_insn = print_insn_big_nios2;
> > +#else
> > +    info->print_insn = print_insn_little_nios2;
> > +#endif
>
> I take it there is no runtime switch for endianness? Most architectures
> eventually got one and moved to a single default endianness for softmmu
> with swizzling for the "other" one (LE for ARM, BE for ppc).

Maybe QEMU should just error out if configured for big-endianness on 
this target.  Per the published Nios II Processor Reference Handbook, 
"The Nios II architecture uses little-endian byte ordering."  When I was 
working on preparing the nios2 binutils patches for submission, Altera 
asked me to retain the big-endian hooks because they didn't want to rule 
out officially supporting that feature.  I had no way to test anything 
big-endian, of course.

-Sandra