Messages in this thread | | | Date | Thu, 17 Aug 2023 09:15:54 -0700 | From | Jakub Kicinski <> | Subject | Re: [PATCH net-next v7 1/6] page_pool: frag API support for 32-bit arch with 64-bit DMA |
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On Thu, 17 Aug 2023 16:57:16 +0300 Ilias Apalodimas wrote: > Why should we care about this? Even an architecture that's 32-bit and > has a 64bit DMA should be allowed to split the pages internally if it > decides to do so. The trick that drivers usually do is elevate the > page refcnt and deal with that internally.
Can we assume the DMA mapping of page pool is page aligned? We should be, right? That means we're storing 12 bits of 0 at the lower end. So even with 32b of space we can easily store addresses for 32b+12b => 16TB of memory. "Ought to be enough" to paraphrase Bill G, and the problem is only in our heads?
Before we go that way - Mina, are the dma-buf "chunks" you're working with going to be fragment-able? Or rather can driver and/or core take multiple references on a single buffer?
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