Date: Tue, 04 Dec 2001 11:58:49 -0800 From: "Srinivas Dharmasanam" <the_srinivas@hotmail.com> To: wpaul@FreeBSD.ORG, ken@kdm.org Cc: jlemon@flugsvamp.com, hackers@FreeBSD.ORG Subject: Re: TCP&IP cksum offload on FreeBSD 4.2 Message-ID: <F385wAz8AWiZAtGYkNU0000c7f8@hotmail.com>
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Hi, I'm using the Netgear GA620 Gig ethernet NIC with Tigon II chip. Do you know if it is possible to increase the buffer size for standard sized ethernet frames from 512 buffers to say, 1024? I assume I'd have to modify the firmware and the host driver to accomodate these buffers. I dont plan to use Jumbo frames at all, and I can reduce the buffers allocated for them if necessary. Thanks, -Srinivas >From: wpaul@FreeBSD.ORG (Bill Paul) >To: ken@kdm.org (Kenneth D. Merry) >CC: jlemon@flugsvamp.com, the_srinivas@hotmail.com, hackers@FreeBSD.ORG >Subject: Re: TCP&IP cksum offload on FreeBSD 4.2 >Date: Sat, 29 Sep 2001 17:02:58 -0700 (PDT) > > > > > On the other hand, the Tigon III > > > is capable of 960 megabits -- about the wire rate limit -- > > > with normal size packets, if you implement software interrupt > > > coelescing (which doesn't help, unless you crank the load up > > > to close to wire speed and/or do more of the stack processing > > > at interrupt time). > >I've been able to get 906Mbps between two Dell PowerEdge 2550 >servers with built-in BCM5700/Tigon III chipsets with a stock >FreeBSD kernel and the bge driver. > > > Having downloadable firmware is actually a huge advantage. You can do > > things with the Tigon II that just aren't possible with any other chip, > > either because they don't have downloadable firmware, or because the >vendor > > won't release firmware source. > > > > This is a problem with the Broadcom Tigon III boards, and to some extent > > with the Tigon II. Basically it looks like the firmware for the Tigon >II > > is very hard to get now that 3Com has control of it, and I don't think > > Broadcom will release the Tigon III firmware. (Assuming it is a > > firmware-based chip.) > >I still have a copy of the last release of the Tigon II firmware and >the development environment (which is what I used to generate the >firmware image included with FreeBSD). As for the Tigon III, there >is a default firmware image included in the EEPROM on the card, which >is auto-loaded when the chip powers up. It is possible for a driver >to load a custom image into the NIC's memory which will override the >auto-loaded one, and it's also possible to load a new image into >the EEPROM, however this requires an additional manual on top of >the BCM5700 driver developer's guide as well as the firmware development >kit, which you can only get from Broadcom/3Com/whatever under NDA. > >These custom images are called "value-add" firmware which are used to >provide features like TCP segmentation, which you can't do with the >default firmware image. Note that the BCM5700/Tigon III only has >a limited amount of on-board RAM (256KB, I think). You're supposed >to be able to attach up to 16MB of static SRAM to the BCM5700. The >BCM5701 doesn't support external SSRAM at all, which I find a little >confusing. > >-Bill _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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