netdev - Re: [PATCH net-next 12/15] eth: fbnic: allocate unreadable page pool for the payloads

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Message-ID: <20250820174521.41251949@kernel.org>
Date: Wed, 20 Aug 2025 17:45:21 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Mina Almasry <almasrymina@...gle.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
 pabeni@...hat.com, andrew+netdev@...n.ch, horms@...nel.org,
 michael.chan@...adcom.com, tariqt@...dia.com, dtatulea@...dia.com,
 hawk@...nel.org, ilias.apalodimas@...aro.org, alexanderduyck@...com,
 sdf@...ichev.me
Subject: Re: [PATCH net-next 12/15] eth: fbnic: allocate unreadable page
 pool for the payloads

On Wed, 20 Aug 2025 16:33:18 -0700 Mina Almasry wrote:
> > +       if (page_pool_rxq_wants_unreadable(&pp_params)) {
> > +               pp_params.flags |= PP_FLAG_ALLOW_UNREADABLE_NETMEM;
> > +               pp_params.dma_dir = DMA_FROM_DEVICE;
> > +  
> 
> Although I'm not sure why the dma_dir needed to change specifically
> for unreadable.

Driver defaults to BIDIR AFAIU to avoid having to reset the
datapath when XDP is bound. But BIDIR is not compatible with
unreadable mem, and for good reason.

Will add to the commit msg.