Date: Thu, 7 Dec 1995 14:52:43 -0600 (CST) From: Mark Tinguely <tinguely@plains.nodak.edu> To: terry@lambert.org Cc: hackers@FreeBSD.ORG Subject: Re: Matrox Meteor & pal... Message-ID: <199512072052.OAA22145@plains.nodak.edu>
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> Out of curiousity, what would really be invovled in running a driver in > its own linear address space so that this wasn't a problem? > > Or must it be physically contiguous? the card uses DMAs to physical memory, and needs physically contiguous memory for each field. we interlace the field into one buffer to make a faster user application use. so packed mode could use two seperate smaller contiguous buffers and planer YUV could be split into 3 YUV (interlaced but seperate Y, U, and V buffers) or 6 (non-interlace Y, U, V buffers) contiguous buffers. In the massive frame capture mode we could go with an array of smaller contiguous chunks. I don't think breaking these up is wise because when you look at grabbing at a high frame rate you want to keep driver and user processing to a minimum. Besides, there is no guarrentee we can get the smaller chunks contiguous after several minutes of allocations/free. --mark.
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