Date: Fri, 13 Sep 2002 00:01:10 -0700 From: Flemming Frøkjær <none@flemming--eiffel.dk.lh.bsd-dk.dk> To: bsd-dk@bsd-dk.dk Subject: Re: Netkort problem
Søren S Jensen wrote:
>
>
> #Du kan også smutte forbi en edb-butik og købe fx. et Intel #Etherexpress
> #Pro S 10/100 som virker godt med FreeBSD. SIS chippen #kommer sikkert til
> #at virke om 6-12 mdr., men kan du leve uden net sålænge???
>
> et lidt billigere alternativ var et realtek 8139 som kan fås på den
> gode side af 100kr sidst jeg kiggede på edbpriser
>
>
>
>
Jeg vil fraråde alt hvad der står realtek 81x9 på.
Nesten alt andet virker bedre.
Prøv at læse komentarerne i driveren til kortet...
/*
* The RealTek 8139 PCI NIC redefines the meaning of 'low end.' This is
* probably the worst PCI ethernet controller ever made, with the possible
* exception of the FEAST chip made by SMC. The 8139 supports bus-master
* DMA, but it has a terrible interface that nullifies any performance
* gains that bus-master DMA usually offers.
*
* For transmission, the chip offers a series of four TX descriptor
* registers. Each transmit frame must be in a contiguous buffer, aligned
* on a longword (32-bit) boundary. This means we almost always have to
* do mbuf copies in order to transmit a frame, except in the unlikely
* case where a) the packet fits into a single mbuf, and b) the packet
* is 32-bit aligned within the mbuf's data area. The presence of only
* four descriptor registers means that we can never have more than four
* packets queued for transmission at any one time.
*
* Reception is not much better. The driver has to allocate a single large
* buffer area (up to 64K in size) into which the chip will DMA received
* frames. Because we don't know where within this region received packets
* will begin or end, we have no choice but to copy data from the buffer
* area into mbufs in order to pass the packets up to the higher protocol
* levels.
*
* It's impossible given this rotten design to really achieve decent
* performance at 100Mbps, unless you happen to have a 400Mhz PII or
* some equally overmuscled CPU to drive it.
*
* On the bright side, the 8139 does have a built-in PHY, although
* rather than using an MDIO serial interface like most other NICs, the
* PHY registers are directly accessible through the 8139's register
* space. The 8139 supports autonegotiation, as well as a 64-bit multicast
* filter.
*
* The 8129 chip is an older version of the 8139 that uses an external PHY
* chip. The 8129 has a serial MDIO interface for accessing the MII where
* the 8139 lets you directly access the on-board PHY registers. We need
* to select which interface to use depending on the chip type.
*/
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