Re: [PATCH 00/10] sh: remove NUMA and SPARSEMEM support

[John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Hi Mike,

On Mon, 2026-04-13 at 13:46 +0300, Mike Rapoport wrote:
> NUMA support for SuperH was introduced a long time ago by commit
> b241cb0c885e ("sh: Support for multiple nodes.")
> 
> 	"... for boards with many different memory blocks that are
> 	 otherwise unused (SH7722/SH7785 URAM and so forth)"
> 
> In reality, this added 128K of memory on sh7722 and sh7785 and 256K on
> shx3 at the expense of all the NUMA related code in the kernel.
> 
> For build of v7.0-rc7 with defconfig and the same configuration with
> CONFIG_NUMA disabled, bloat-o-meter reports difference of ~76k. Disabling
> CONFIG_SPARSMEM on top increases the difference to ~94k. And that's only
> overhead in code and static data that does not take into the account data
> structures allocated at run time.
> 
> And all this overhead has been there for nothing for almost 8 years
> because since commit ac21fc2dcb40 ("sh: switch to NO_BOOTMEM")
> those additional "nodes" could not be used by the core MM because the
> maximal pfn for ZONE_NORMAL was cut out at the end of the normal memory.
> 
> Mike Rapoport (Microsoft) (10):
>   sh: remove CONFIG_NUMA and realted configuration options
>   sh: mm: remove numa.c
>   sh: mm: drop allocate_pgdat()
>   sh: remove setup_bootmem_node() and plat_mem_setup()
>   sh: drop dead code guarded by #ifdef CONFIG_NUMA
>   sh: drop include/asm/mmzone.h
>   init/Kconfig: drop ARCH_WANT_NUMA_VARIABLE_LOCALITY
>   sh: init: remove call the memblock_set_node()
>   sh: remove SPARSEMEM related entries from Kconfig
>   sh: drop include/asm/sparsemem.h

Thanks a lot for the series. It will take me some time to review and I expect
it to be taken for v7.2. FWIW, I actually own several boards using the SH-7785LCR
CPU and I issues booting kernels newer than 6.5 on these so I'm wondering whether
this broken feature might be to blame?

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer
`. `'   Physicist
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913