Re: [PATCH v2 0/7] Kernel huge I/O mapping support

[Ingo Molnar]

* Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

> <reads the code>
> 
> Oh.  We don't do any checking at all.  We're just telling 
> userspace programmers "don't do that".  hrm.  What are 
> your thoughts on adding the overlap checks to the kernel?

I have requested such sanity checking in previous review as 
well, it has to be made fool-proof for this optimization to 
be usable.

Another alternative would be to make this not a transparent 
optimization, but a separate API: ioremap_hugepage() or so.

The devices and drivers dealing with GBs of remapped pages 
is still relatively low, so they could make explicit use of 
the API and opt in to it.

What I was arguing against was to make it a CONFIG_ option: 
that achieves very little in practice, such APIs should be 
uniformly available.

Thanks,

	Ingo
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