Re: [PATCH] MIPS: lib: prefetch ahead in csum_partial()

[Maciej W. Rozycki]

On Tue, 13 Oct 2026, kernel test robot wrote:

> config: mips-rbtx49xx_defconfig (https://download.01.org/0day-ci/archive/20261013/202610131201.wWk11MLy-lkp@xxxxxxxxx/config)
> compiler: mips-linux-gcc (GCC) 16.1.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261013/202610131201.wWk11MLy-lkp@xxxxxxxxx/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202610131201.wWk11MLy-lkp@xxxxxxxxx/
> 
> All errors (new ones prefixed by >>):
> 
>    Assembler messages:
> >> arch/mips/lib/csum_partial.S:202: Error: opcode not supported on this processor: r4600 (mips3) `pref 0,0x100($4)'
>    arch/mips/lib/csum_partial.S:203: Error: opcode not supported on this processor: r4600 (mips3) `pref 0,0x120($4)'
>    arch/mips/lib/csum_partial.S:204: Error: opcode not supported on this processor: r4600 (mips3) `pref 0,0x140($4)'
>    arch/mips/lib/csum_partial.S:205: Error: opcode not supported on this processor: r4600 (mips3) `pref 0,0x160($4)'

 So oddly enough we're missing Tx49 support in the toolchain and we've 
only managed to survive with CPU_HAS_PREFETCH enabled for CPU_TX49XX 
because it also implies DMA_NONCOHERENT via MACH_TX49XX -> MACH_TXX9, 
which in turn disables stuff in arch/mips/lib/memcpy.S.

 Quite straighforward to fix in binutils since docs are available (as in: 
I have a copy), but do we have any users?  Geert?

  Maciej