On Fri, Aug 07, 2026 at 06:16:06PM +0200, David Hildenbrand (Arm) wrote: > On 8/7/26 17:54, Thierry Reding wrote: > > From: Thierry Reding <[email protected]> > > > > There is no technical reason why there should be a limited number of CMA > > regions, so extract some code into helpers and use them to create extra > > functions (cma_create() and cma_free()) that allow creating and freeing, > > respectively, CMA regions dynamically at runtime. > > > > The static array of CMA areas cannot be replaced by dynamically created > > areas because for many of them, allocation must not fail and some cases > > may need to initialize them before the slab allocator is even available. > > To account for this, keep these "early" areas in a separate list and > > track the dynamic areas in a separate list. > > > > Signed-off-by: Thierry Reding <[email protected]> > > --- > > Sorry that I didn't get to reply earlier to > > https://lore.kernel.org/all/anS0nxAwCXGWZRl9@orome/ > > But I am still not convinced why we shouldn't just have a single array that > grows dynamically. > > " > After replying to T.J. I think this static array is actually a nice > feature in a way. It allows us to more easily make a distinction between > the regular CMA regions created from reserved-memory regions that > represent classic carveouts, and the more versatile CMA areas that could > be used for any purpose. > > Telling the two types apart could obviously also be solved using some > kind of flag stored with the CMA area, but at this point I don't really > see a reason why the two lists would need to be unified. > " > > Really, cma_for_each_early_area() + cma_for_each_area() is just nasty. > > I'd strongly vote to unify unless there is a very good reason to do it > separately.
Marek had an interesting suggestion to extend CMA with fixed address or range allocations, in which case we would only need a single CMA area. If that works and is acceptable, there's not much need any longer for cma_create()/cma_free(). Thierry
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