Date: Sun, 30 Jul 1995 17:34:33 +0200 (MET DST) From: J Wunsch <j@uriah.heep.sax.de> To: gibbs@freefall.cdrom.com (Justin T. Gibbs) Cc: joerg_wunsch@uriah.heep.sax.de, terry@cs.weber.edu, freebsd-current@freebsd.org, babb@freebsd.org Subject: Re: Update on my aic driver problems Message-ID: <199507301534.RAA15394@uriah.heep.sax.de> In-Reply-To: <199507301527.IAA12070@freefall.cdrom.com> from "Justin T. Gibbs" at Jul 30, 95 08:27:01 am
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As Justin T. Gibbs wrote: > > >> The 6260 doesn't support scatter/gather, I believe. > >Hmm, well. Scatter/gather is a required feature for FreeBSD, ain't > >it? > > No, its not. What you'll have to do is allocate a 64k contiguous > staging buffer and do the transaction from there. Since scatter/gather > is handled at the controller driver layer, the rest of the SCSI system > makes no assumptions about it use... it just happens that most transactions > are to buffers that are not physically contiguous, so if you use DMA, > you must have the staging buffer. It should be possible to get it to > work, but the performance won't be that great. Oops. The aic driver doesn't use DMA (it's in the TODO list at the beginning of the file), so i'm not sure now: is this difference a problem at all, or will i have to look elsewhere? Is there any doc available on the Adaptec chips? -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ Never trust an operating system you don't have sources for. ;-)
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