Re: [PATCH v2 1/5] drivers: of: add initialization code for reserved memory

[Tomasz Figa]

On 11.02.2014 21:19, Josh Cartwright wrote:
> On Tue, Feb 11, 2014 at 09:04:21PM +0100, Tomasz Figa wrote:
> > On 11.02.2014 21:02, Benjamin Herrenschmidt wrote:
> > > On Tue, 2014-02-11 at 19:01 +0000, Grant Likely wrote:
> > >
> > > > > except that the former IMHO better suits the definition of memory
> > > > > region, which I see as a single contiguous range of memory and can be
> > > > > simplified to have a single reg entry per region.
> > > >
> > > > My point is rather if multiple reg tuples are found in a reserved memory
> > > > node, the kernel must respect them and reserve the memory. I'm not
> > > > arguing about whether or not that makes for a good binding.
> > >
> > > agreed.
> >
> > My point is why, if the binding defines that just a single tuple should be
> > provided.
>
> FWIW, the usecase I had mentioned in reply to Grant in the patch 5/5
> thread [1] could make use of this.  The shared memory region is split
> into a main chunk and several "auxiliary" chunk, but collectively these
> regions all share the same heap state.
>
>    Josh
>
> 1: http://lkml.kernel.org/r/20140205192502.GO20228@xxxxxxxxxxxxxxxxxx

The use case seems fine, but I believe it could be properly represented 
in device tree using multiple single-reg regions as well, unless the 
consumer can request a block of memory that crosses boundary of two 
sub-regions specified by reg entries of single region.

Best regards,
Tomasz
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