Re: M68k backend has landed in LLVM - NetBSD support

[Chris Hanson <cmhanson%eschatologist.net@localhost>]

On Mar 23, 2021, at 4:27 AM, John Paul Adrian Glaubitz <glaubitz%physik.fu-berlin.de@localhost> wrote:
> 
> Since the M68k has landed a few days ago in LLVM upstream [1] I wonder whether
> anyone in the NetBSD community is interested in adding NetBSD support so that
> clang can be used as an alternative compiler for NetBSD/m68k.
> 
> Adrian
> 
>> [1] https://github.com/llvm/llvm-project/tree/main/llvm/lib/Target/M68k

One thing I wonder is whether LLVM/clang can actually be built and run on NetBSD/m68k: NetBSD's VM on m68k only uses a single root page for the page tables, so with 4KB pages you have a hard VM ceiling of only a couple hundred megabytes, and with 8KB pages you're still under a gigabyte.

Granted modern GCC will take a significant amount of time and memory to build as well, but I don't think it's as heavy in that respect as LLVM. Maybe it's time for someone versed in the intricacies of the m68k MMUs to add support for more root pages…

  -- Chris