Date: Tue, 29 May 2001 16:20:33 -0500 From: Bob Willcox <bob@immure.com> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: "Jesper Skriver <jesper@skriver.dk> hackers list" <freebsd-hackers@freebsd.org> Subject: Re: How to disable software TCP checksumming? Message-ID: <20010529162033.O19771@luke.immure.com> In-Reply-To: <15124.3579.211031.178700@grasshopper.cs.duke.edu>; from gallatin@cs.duke.edu on Tue, May 29, 2001 at 05:00:43PM -0400 References: <20010529144114.I19771@luke.immure.com> <20010529221107.C49875@skriver.dk> <15124.3579.211031.178700@grasshopper.cs.duke.edu>
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Thanks Drew! This helps alot! Bob On Tue, May 29, 2001 at 05:00:43PM -0400, Andrew Gallatin wrote: > > > Jesper Skriver writes: > > On Tue, May 29, 2001 at 02:41:14PM -0500, Bob Willcox wrote: > > > Hi, > > > > > > I am working on a device driver for a GSN adapter that has hardware CRC > > > checking and need to know if there is a way to disable the software CRC > > > checking for TCP? This is on a FreeBSD 4.2-stable system. > > > > Eegads. I think the original poster wanted to be able to use the > hardware CRC features of his nic, not ignore checksums altogther. > > Bob -- Take a look at the /sys/pci/if_ti.c driver for an example of > how to use hardware checksum assist. > > On the recieve side, you want to set the m_pkthdr.csum_flags > appropriately (depending on what your device can do) on each recieve, > as well as fill in the actual checksum in m_pkthdr.csum_data. > > On the send side, you need to specify what your device is capable of > assisting with in the if_hwassist field of your driver's ifp struct. > Packets will come down w/o those fields filled in. The stack will > expect your device to calculate those fields in hardware. > > I beleive these features appeared around 4.1, so if this is a 3rd > party driver, you may want to check __FreeBSD_version >= 410000. > > > Hope this helps, > > Drew > > ------------------------------------------------------------------------------ > Andrew Gallatin, Sr Systems Programmer http://www.cs.duke.edu/~gallatin > Duke University Email: gallatin@cs.duke.edu > Department of Computer Science Phone: (919) 660-6590 -- Bob Willcox Egotist, n.: bob@vieo.com A person of low taste, more interested in himself than me. Austin, TX -- Ambrose Bierce, "The Devil's Dictionary" To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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