Re: [discuss] Re: x86_64: 2.6.14-rc4 swiotlb broken

On Mon, 17 Oct 2005, Linus Torvalds wrote:
> Why? Because the bootmem memory should still be allocated low-to-high by
> default, which means that as logn as NODE(0) has _enough_ memory in the
> DMA range, we should be ok.
>
> So I _think_ the simple one-liner NODE(0) patch is sufficient, and should
> work (and is a lot more acceptable for 2.6.14 than switching the node
> ordering around yet again, or doing bigger surgery on the bootmem code).
>
> So the only thing that worried me (and made me ask whether there might be
> machines where it doesn't work) is if some machines might have their high
> memory (or no memory at all) on NODE(0). It does sound unlikely, but I
> simple don't know what kind of strange NUMA configs there are out there.
>
> And I'm definitely only interested in machines that are out there, not
> some theoretical issues.

what about x86_64 machines with 8G of ram connected to each CPU (4x2G 
DIMMs), not exactly common, but also not that rare.

also if CPU's are registered from high to low would a 2 CPU box with 8G of 
ram connected to one CPU and no ram connected to the second CPU match your 
problem case (I know that's a sub-optimal layout, but it's legal)

David Lang


>                         Linus
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