Date: Sun, 14 Mar 1999 11:56:45 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Amancio Hasty <hasty@rah.star-gate.com> Cc: Wes Peters <wes@softweyr.com>, Cory Kempf <ckempf@enigami.com>, Bill Paul <wpaul@skynet.ctr.columbia.edu>, freebsd-hackers@FreeBSD.ORG Subject: Re: Gigabit ethernet -- what am I doing wrong? Message-ID: <199903141956.LAA93779@apollo.backplane.com> References: <199903141945.LAA87562@rah.star-gate.com>
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:
:If the pci device has the concept of a program store like in the case of
:a bt848 chipset it is conceivable for dma or internal operations to do a retry.
:It is a different issue if the network chipset designers chose not to have
:a programmable dma or process control like in the bt848 .
:
:
: Best Regards,
: Amancio
I know of *NO* DMA device that can do 'retries' of the magnitude that would
be required, and this in any case does not solve the problem of the FIFO
overflowing.
Network chipset designers tend to assume that they will be DMAing to or
from main memory somewhere such that the DMA will not get 'stuck'.
FIFOs are typically only large enough to hold a packet or two, and many
can only hold a partial packet.
-Matt
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