Date: Sat, 22 Mar 1997 14:43:52 +0500 (ESK) From: "Serge A. Babkin" <babkin@hq.icb.chel.su> To: ccsanady@nyx.pr.mcs.net (Chris Csanady) Cc: hackers@FreeBSD.ORG Subject: Re: ep driver memory management question.. Message-ID: <199703220943.OAA01530@hq.icb.chel.su> In-Reply-To: <199703181039.EAA03782@nyx.pr.mcs.net> from "Chris Csanady" at Mar 18, 97 04:39:03 am
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> > I'm not very familiar with net drivers, but I would like to rewrite the ep > driver to use contiguous packet buffers. I am curious about how it allocates > memory for packets, and if there are any limitations. From the code, it looks > as if it just allocates an mbuf, dmas into it, and passes it off to It allocates mbufs in bucnhes them uses them as needed. > ether_input. Is this correct? I thought that there was a 16M limit on dma I don't know about newer cards supported by it but the original 3c5[07]9 does not have any DMA! It uses ins/outs port access instructions. > for the isa bus without bouncing, but I didn't see anything that dealt with > this. Is this because all the mbufs get allocated at boot, so its just the > way it turns out? If so, I will need to allocate a contiguous chunk of memory > for the driver upon boot. How would I do this? Again, it does not use DMA. I think the best idea will be to use mbuf clusters like David Greenman does in his drivers. Look at /sys/pci/if_fxp.c for example. -SB
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