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Date:   Wed, 21 Aug 2019 13:37:57 -0700
From:   Jakub Kicinski <jakub.kicinski@netronome.com>
To:     Thomas Bogendoerfer <tbogendoerfer@suse.de>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Ralf Baechle <ralf@linux-mips.org>,
        Paul Burton <paul.burton@mips.com>,
        James Hogan <jhogan@kernel.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Lee Jones <lee.jones@linaro.org>,
        "David S. Miller" <davem@davemloft.net>,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Alessandro Zummo <a.zummo@towertech.it>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jslaby@suse.com>,
        Evgeniy Polyakov <zbr@ioremap.net>, linux-doc@vger.kernel.org,
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        linux-input@vger.kernel.org, netdev@vger.kernel.org,
        linux-rtc@vger.kernel.org, linux-serial@vger.kernel.org,
        Jesper Dangaard Brouer <brouer@redhat.com>
Subject: Re: [PATCH v5 10/17] net: sgi: ioc3-eth: rework skb rx handling
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On Wed, 21 Aug 2019 16:28:47 +0200, Thomas Bogendoerfer wrote:
> > This looks like a DMA engine alignment requirement, more than an
> > optimization.  
> 
> that true, there are two constraints for the rx buffers, start must be aligned
> to 128 bytes and a buffer must not cross a 16kbyte boundary. I was already
> thinking of allocating pages and chop them up. Is there a Linux API available,
> which could help for implementing this ?
> 
> I'll probably drop this patch or only change the skb_put stuff plus RX_BUF_SIZE
> define.

Sounds a little like frag allocator (napi_alloc_frag()/
netdev_alloc_frag()), but I'm not sure you'd have sufficient control
to skip over the 16k boundary.. Perhaps others have better suggestions.