linux-kernel - Re: [PATCH net-next v18 07/14] memory-provider: dmabuf devmem memory provider

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Message-ID: <20240812171548.509ca539@kernel.org>
Date: Mon, 12 Aug 2024 17:15:48 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Pavel Begunkov <asml.silence@...il.com>
Cc: Mina Almasry <almasrymina@...gle.com>, netdev@...r.kernel.org,
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Subject: Re: [PATCH net-next v18 07/14] memory-provider: dmabuf devmem
 memory provider

On Mon, 12 Aug 2024 20:04:41 +0100 Pavel Begunkov wrote:
> >> Also don't see the upside of the explicit "non-capable" flag,
> >> but I haven't thought of that. Is there any use?  
> 
> Or maybe I don't get what you're asking, I explained
> why to have that "PP_IGNORE_PROVIDERS" on top of the flag
> saying that it's supported.
> 
> Which "non-capable" flag you have in mind? A page pool create
> flag or one facing upper layers like devmem tcp?

Let me rephrase - what's the point of having both PP_PROVIDERS_SUPPORTED
and PP_IGNORE_PROVIDERS at the page pool level? PP_CAP_NET(MEM|IOV),
and it's either there or it's not.

If you're thinking about advertising the support all the way to the
user, I'm not sure if page pool is the right place to do so. It's more
of a queue property.

BTW, Mina, the core should probably also check that XDP isn't installed
before / while the netmem is bound to a queue.