Re: [RFC: DMA_PMD 00/22] DMA_PMD: PMD_SIZE-backed IO buffer pools

[David Hildenbrand (Arm)]

On 10/13/26 12:42, Robin Murphy wrote:
> On 12/10/2026 8:43 pm, David Hildenbrand (Arm) wrote:
>> On 10/12/26 16:45, Luigi Rizzo wrote:
>>> On Mon, Oct 12, 2026 at 3:51 PM David Hildenbrand (Arm)
>>> <david@xxxxxxxxxx> wrote:
>>>
>>> I had to call it something... an earlier prototype used the name IOMMU_2M,
>>> but I didn't want to suggest that the design was limited to 2M (it is not).
>>>
>>> Aside from the name, the _current_ prototype restricts to 2M allocations,
>>> exactly because too large units are expensive and wasteful.
>>>
>>> In the code, decoupling the allocation size from the PMD size is trivial.
>>
>> Yeah, we should do that.
>>
>> We should probably just find a way to describe that this is a POOL that focuses
>> on physical contiguity in some configured granularity.
> And since it's intended for DMA we could call it dma_pool and oh look it already
> exists...

Heh, I did have "DMA_POOL" in mind when writing my reply.

> 
> Sure the current implementation is capped at PAGE_SIZE for allocation (and thus
> mapping too), but I don't see why that couldn't just be made more flexible.

That intuitively sounds like the right direction.

-- 
Cheers,

David