Re: looking for cheap 100baset cards

[Andi Kleen]

On Fri, Jun 16, 2000 at 09:29:54AM -0400, Jeff Garzik wrote:
> For transmitted packets, there are four packet buffers (much better than
> a ring buffer!) used for outgoing packets.  BUT...  each packet must be
> aligned to a 32-bit address, which is a silly requirement:  Since Linux
> aligns its IP header on such a boundary, the ethernet header is usually
> aligned on a 16-bit boundary.  This is not sufficient for RTL8139, so
> the entire packet must be copied (slow!) before it can be transmitted.

Actually the Tulip has the same problem, at least for RX. Similar do
have some alpha chipsets for their virtual bus mastering.

I'm planning some changes in 2.5 to support such hardware restrictions
better (mainly by only copying the header instead of the full data packet).
2.5 will also most likely see non linear skbuffs.


-Andi
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