Re: [PATCH v2] dma-contiguous: define proper name for global cma region

[John Stultz <jstultz@google.com>]

On Tue, Aug 1, 2023 at 10:18 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Tue, Aug 01, 2023 at 10:42:42PM +0530, Pintu Agarwal wrote:
> > > I agree that reserved is not a very useful name.  Unfortuately the
> > > name of the region leaks to userspace through cma_heap.
> > >
> > > So I think we need prep patches to hardcode "reserved" in
> > > add_default_cma_heap first, and then remove the cma_get_name
> > > first.
> >
> > Sorry, but I could not fully understand your comments.
> > Can you please elaborate a little more what changes are required in
> > cma_heap if we change "reserved" to "global-cma-region" ?
>
> Step 1:
>
> Instead of setting exp_info.name to cma_get_name(cma);
> in __add_cma_heap just set it to "reserved", probably by passing a name
> argument.  You can also remove the unused data argument to __add_cma_heap
> and/or just fold that function into the only caller while you're at it.

So, forgive me, I've not had a chance to look into this, but my
recollection was "reserved" is the name we see on x86, but other names
are possibly provided via the dts node?

I believe on the hikey board its "linux,cma" is the name, so forcing
it to reserved would break that.

Maybe instead add a compat config option to force the cma name (so x86
can set it to "default" if needed)?

thanks
-john