Re: [PATCH] dma/direct: turn ARCH_ZONE_DMA_BITS into a variable

[Christoph Hellwig]

On Thu, Oct 31, 2019 at 04:53:13PM +0100, Nicolas Saenz Julienne wrote:
> > > +#define ARM64_ZONE_DMA_BITS	30
> > > +
> > >  /*
> > >   * We need to be able to catch inadvertent references to memstart_addr
> > >   * that occur (potentially in generic code) before arm64_memblock_init()
> > > @@ -424,6 +427,8 @@ void __init arm64_memblock_init(void)
> > >  	else
> > >  		arm64_dma_phys_limit = PHYS_MASK + 1;
> > >  
> > > +	zone_dma_bits = ARM64_ZONE_DMA_BITS;
> > > +
> > >  	reserve_crashkernel();
> > 
> > This actually adds a new limit, as there wasn't one before for arm64.
> 
> Well, as zone_dma_bits is only relevant in dma/direct when ZONE_DMA is defined
> I figured it doesn't matter if the variable is set conditionally to ZONE_DMA or
> not.

I'd much prefer that to do separately.