Hi David Laight, Thank you so much~~ 1. Hardware based on FPGA, it dose not support buffer chaining. 2. How dose the dma map support buffer chaining function? 3. On the align issue, the hardware designer start to fix it, maybe it's a better way.
-----????----- ???: netdev-ow...@vger.kernel.org [mailto:netdev-ow...@vger.kernel.org] ?? David Laight ????: 2011?6?17? 18:16 ???: yangy...@neusoft.com; Holger Brunck; linuxppc-dev@lists.ozlabs.org ??: net...@vger.kernel.org; Clive Stubbings; Vitaly Bordug ??: RE: [PATCH] fs_enet: fix freescale FCC ethernet dp buffer alignment > Hello, > Motioned to the memory aligned, now there is such requirement: > When the driver send an packet to hardware, the skb's address passed by > stack do a dma map into hardware, the skb's dma address must > be 64-byte aligned. Does the hardware support buffer chaining? In which case you only need to copy the data upto the first 64 byte boundary into another buffer. Actually, given that you are likely to have to fixup every fragment of the frame being transmitted, if might be worth allocating a fixed transmnit buffer area and copying the frames into it prior to sending. Certainly you need to allow for transmits made up of a significant number of small buffers linked together. Really you should beat up the hardware designers! Copying the data to even a 4 byte boundary is almost always a misaligned copy. Typically this only applies to the receive dma - when writing a 2 byte pad before the frame data would be much better. David -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html --------------------------------------------------------------------------------------------------- Confidentiality Notice: The information contained in this e-mail and any accompanying attachment(s) is intended only for the use of the intended recipient and may be confidential and/or privileged of Neusoft Corporation, its subsidiaries and/or its affiliates. If any reader of this communication is not the intended recipient, unauthorized use, forwarding, printing, storing, disclosure or copying is strictly prohibited, and may be unlawful.If you have received this communication in error,please immediately notify the sender by return e-mail, and delete the original message and all copies from your system. Thank you. --------------------------------------------------------------------------------------------------- _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev