Re: [PATCH 3/8] mm: cma: Export a few symbols
From: Michal Hocko
Date: Mon Feb 20 2017 - 07:36:30 EST
On Mon 13-02-17 14:44:16, Maxime Ripard wrote:
> Hi Michal,
> On Thu, Feb 09, 2017 at 08:20:47PM +0100, Michal Hocko wrote:
> > [CC CMA people]
> > On Thu 09-02-17 17:39:17, Maxime Ripard wrote:
> > > Modules might want to check their CMA pool size and address for debugging
> > > and / or have additional checks.
> > >
> > > The obvious way to do this would be through dev_get_cma_area and
> > > cma_get_base and cma_get_size, that are currently not exported, which
> > > results in a build failure.
> > >
> > > Export them to prevent such a failure.
> > Who actually uses those exports. None of the follow up patches does
> > AFAICS.
> This is for the ARM Mali GPU driver that is out of tree, unfortunately.
We do not export symbols which do not have any in-tree users.
> In one case (using the legacy fbdev API), the driver wants to (and
> probably should) validate that the buffer as indeed been allocated
> from the memory allocation pool.
> Rob suggested that instead of hardcoding it to cover the whole RAM
> (which defeats the purpose of that check in the first place), we used
> the memory-region bindings in the DT and follow that, which does work
> great, but we still have to retrieve the base address and size of that
> region, hence why this patches are needed.
Anyway I would suggest talking to CMA people to find a better API for
modules to use...