Re: ioremap_page_range: remapping of physical RAM ranges

[John Hubbard <jhubbard@nvidia.com>]

On 01/28/2017 01:55 PM, Ahmed Samy wrote:
> On Sat, Jan 28, 2017 at 01:48:46PM -0800, John Hubbard wrote:
>> Quick question, what do you mean "a function as part of vmalloc"?
> Take a look at `vmap()', it should be like that API.  Dunno if vmap can be used
> in place, haven't tried, maybe can get `struct page` and then use vmap?  I
> don't know, what do you think?

Right, vmap is probably what you're looking for here. The way this story usually goes in my 
experience is: if you're actually dealing with real RAM, you are also dealing in struct pages. So 
you lookup the struct pages, keep track of them, (maybe also pin them with get_user_pages), and then 
map them with vmap.

Beyond the out-of-tree driver that I'm supporting (which uses vmap in that way), there are also a 
*lot* of in-tree examples that also do it.

Are you buying this? :)

thanks
john h

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