mm/slab.h "unknown type name 'u128'"

[DiTBho Down in The Bunny hole <downinthebunnyhole@xxxxxxxxx>]

hi
I am trying to compile recent >= kernel-6.12.*
with the toolchain hppa64-unknown-linux-gnu
+ binutils-v2.34.0
+ gcc-v9.3.0

The process stops with an error

In file included from mm/mempool.c:21:
mm/slab.h:25:9: error: unknown type name 'u128'
   25 | typedef u128 freelist_full_t;
      |         ^~~~

where "u128" should be defined?
Is my cc too old?

Let me know
D.