Date: Sun, 30 Jul 1995 09:04:06 -0700 From: "Justin T. Gibbs" <gibbs@freefall.cdrom.com> To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) Cc: terry@cs.weber.edu, freebsd-current@freebsd.org, babb@freebsd.org Subject: Re: Update on my aic driver problems Message-ID: <199507301604.JAA13623@freefall.cdrom.com> In-Reply-To: Your message of "Sun, 30 Jul 95 17:34:33 %2B0200." <199507301534.RAA15394@uriah.heep.sax.de>
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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? It doesn't look like it does S/G either. I would think there are other differences in the chips then. > >Is there any doc available on the Adaptec chips? You can get them from the Adaptec Technical Documents department, but I don't know if they ship overseas. >-- >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. ;-) -- Justin T. Gibbs =========================================== Software Developer - Walnut Creek CDROM FreeBSD: Turning PCs into workstations ===========================================
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