Re: [PATCHv3 2/4] x86/64/mm: Make SPARSEMEM_VMEMMAP the only memory model

[Dave Hansen]

On 5/16/25 06:45, Ingo Molnar wrote:
> Isn't it the other way around? MAX_PHYS{MEM,ADDR}_BITS are now *always* 
> dynamic, their value depending on whether LA57 is available and used.

MAX_PHYS{MEM,ADDR}_BITS were always intended to be the compile-time
maximums on the architecture. They're static on every architecture
except x86 and some arm64 configs (who probably copied x86).

That's why having them be dynamic broke non-vmemmap sparsemem.

But we also seems to have defined MAXMEM to derive from MAX_PHYSMEM_BITS
and MAXMEM cascades into a bunch of other stuff, including KASAN. So we
can't just make them static again, I guess.

The only option would be to make them static when using non-vmemmap
sparsemem. But that's new-ish, and probably won't get any testing.

I guess there's not much we can do about it.