Re: ERROR: modpost: "__divsi3_table" [lib/lz4/lz4_compress.ko] undefined!

[Arnd Bergmann]

On Mon, Dec 6, 2021 at 11:30 AM kernel test robot <lkp@xxxxxxxxx> wrote:
> First bad commit (maybe != root cause):
> commit: 570a82b9c36f76a5959b5e47900629b0d413931d media: i2c: select V4L2_ASYNC where needed

Right, that is clearly unrelated.

> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>
> All errors (new ones prefixed by >>, old ones prefixed by <<):
>
> >> ERROR: modpost: "__divsi3_table" [lib/lz4/lz4_compress.ko] undefined!

lz4 was recently updated, and apparently now does a 32-bit division. I
assume this
is the decompressor, as arch/mips had similar problems.

The possible fixes are:

- disable lz4 compressed kernels on xtensa
- change lz4 to not perform any division
- change the xtensa decompressor to include the divsi3 helper code from the
  main kernel, see fbf3bce45821 ("MIPS: boot/compressed/: add __ashldi3 to
  target for ZSTD compression")

        Arnd