Re: [PATCH -next] RISCV: Add some depends for NUMA

[Kefeng Wang]

On 2021/2/5 14:58, Palmer Dabbelt wrote:
> On Wed, 03 Feb 2021 06:23:43 PST (-0800), wangkefeng.wang@xxxxxxxxxx 
> wrote:
> > The numa feature is useless for riscv32 platform(MAXPHYSMEM_1GB if 
> > 32bit),
>
> I'm not convinced of that.  There's no reason NUMA shouldn't work on 
> 32-bit, it
> doesn't depend on having a large amount of memory just having non-uniform
> memory.  I could buy the argument that build a 32-bit NUMA system 
> would be
> wacky, but IIUC it works now and I don't see any reason to throw that 
> away.

I think the RV32 won't benefit from NUMA, there's no too much memory 
support on RV32,

and it may increase the Image size,  so I decided to drop support for RV32.

> > and it should depends on SMP feature, this also fix the build error,
>
> I can buy that CONFIG_NUMA doesn't really make sense without 
> CONFIG_SMP, as
> there's not a whole lot to do, but I also don't see any reason from 
> disallowing
> users from picking it.  arm64 allows !SMP && NUMA, and I don't see any 
> reason
> it wouldn't work just as well for us.

ARM64 won' support !SMP after following patch, and for most 
architecture,  the NUMA feature

depends or select SMP feature.


commit 4b3dc9679cf779339d9049800803dfc3c83433d1
Author: Will Deacon <will@xxxxxxxxxx>
Date:   Fri May 29 18:28:44 2015 +0100

    arm64: force CONFIG_SMP=y and remove redundant #ifdefs



> >   riscv64-buildroot-linux-gnu-ld: mm/page_alloc.o: in function `.L0 ':
> >   page_alloc.c:(.text+0x4808): undefined reference to 
> > `node_reclaim_distance'
>
> The only instance of node_reclaim_distance I see in mm/page_alloc.c is 
> already
> guarded with CONFIG_NUMA, but the definition of node_reclaim_distance 
> isn't.
> I'll send out some patches to add the guard which might make sorting 
> this out
> earlier, but I don't see it fixing any failures.