Date: Thu, 4 Apr 2002 18:07:46 -0800 (PST) From: Matthew Jacob <mjacob@feral.com> To: Terry Lambert <tlambert2@mindspring.com> Cc: Andrew Gallatin <gallatin@cs.duke.edu>, freebsd-current@freebsd.org, gibbs@freebsd.org Subject: Re: BUS_SPACE_MAXSIZE & isp driver. Message-ID: <Pine.BSF.4.21.0204041807070.78599-100000@beppo> In-Reply-To: <3CAD05FD.4FE5B863@mindspring.com>
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On Thu, 4 Apr 2002, Terry Lambert wrote: > Matthew Jacob wrote: > > Neither is really applicable here. The actual limits for alpha depend on the > > platforma and how you implement it. Typically, the bigger alphas have been > > implemented with a 2GB direct mapped window, and then, if they have it, a S/G > > map setup for the rest (if any) of memory, which also can include ISA mapping. > > Thanks for the clarification. I was confusing BUS_SPACE_MAXSIZE > with BUS_SPACE_MAXSIZE_24BIT and BUS_SPACE_MAXSIZE_32BIT. > > It's probably too late to rename BUS_SPACE_MAXSIZE to something > like BUS_SPACE_MAXXFER. 8-(. Yes. If we've understood it at all. There are no documents really describing it. > > > > The current Alpha 2.4.18 Linux implementation is quite happy to DMA to > 4GB > > on quite a few alphas. > > Ah. Reference code. > > > > BUS_SPACE_MAXSIZE seems to be related to the 'largest xfer you will be allowed > > to do at one time'- which is wrong because MAXPHYS is larger. > > Yeah, I get that now. No need to beat me up, I can take care > of it myself. 8-) 8-). No, no.... at least you showed some interest :-) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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