Re: Network inteface w/ DMA

Alan Cox (alan@lxorguk.ukuu.org.uk)
Fri, 4 Sep 1998 18:55:36 +0100 (BST)


> can send/receive packets via ISA DMA. Is there any way of telling kernel
> to pass a DMA-able memory only to the dev->hard_start_xmit()

No you need to use bounce buffers. Theres an example in the z85230 driver
on ftp.linux.org.uk:pub/linux/alan - thats a sync card using bounce
buffers when needed

> (The rx side is easy because the skb is allocated in the device's
> own interrupt routine and I can use alloc_skb(..., ...|GFP_DMA) here).

Be aware that all the atomic memory pools may not contain any ISA DMA memory
and that may be a stable state. ie dont do it , or if you do have
a bounce buffer fallback

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