Date: Wed, 5 Nov 1997 23:31:13 +0100 From: j@uriah.heep.sax.de (J Wunsch) To: freebsd-current@FreeBSD.ORG Subject: Re: memory out of range??? Message-ID: <19971105233113.DC28602@uriah.heep.sax.de> In-Reply-To: <199711051450.JAA20238@khavrinen.lcs.mit.edu>; from Garrett Wollman on Nov 5, 1997 09:50:24 -0500 References: <345FC6CF.73D2D1A4@excite.com> <Pine.BSF.3.96.971104212044.5702C-100000@shell.uniserve.com> <199711051450.JAA20238@khavrinen.lcs.mit.edu>
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As Garrett Wollman wrote: > > Bounce buffers (for ISA devices that require DMA: aha, and some > > ethernets) > > And floppy disks! But these are different bounce buffers. Floppy disks are using the motherboard DMAC, while options BOUNCE_BUFFERS refers to busmaster DMA. The motherboard DMA is much more crap^H^H^H^Hlimited so it requires bounce buffers even for a number of transfers below the 16 MB limit (due to the awful hack they're calling `page registers' that reminds me more of my old CP/M machine than of a serious computer). -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)
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