Date: Wed, 18 Jun 2003 20:12:07 +0200 From: Bernd Walter <ticso@cicely12.cicely.de> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: freebsd-alpha@freebsd.org Subject: Re: 5.1beta2 on Alpha ES40 w/ 32GB pys ram Message-ID: <20030618181206.GV3626@cicely12.cicely.de> In-Reply-To: <16112.39524.638824.307800@grasshopper.cs.duke.edu> References: <16094.16676.273466.121560@grasshopper.cs.duke.edu> <20030613190624.W36168-100000@mail.chesapeake.net> <16110.27799.68056.48679@grasshopper.cs.duke.edu> <20030618005958.GD3626@cicely12.cicely.de> <20030618024716.GE3626@cicely12.cicely.de> <16111.55358.756861.374441@grasshopper.cs.duke.edu> <20030618120004.GG3626@cicely12.cicely.de> <16112.39524.638824.307800@grasshopper.cs.duke.edu>
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On Wed, Jun 18, 2003 at 12:59:16PM -0400, Andrew Gallatin wrote: > > Bernd Walter writes: > > > > How do you tell? Is there someting in config space, or do you just > > > check the device's docs? > > > > I've checked the memory base registers. > > A memory base register return bit set to zero 0 and bit2/1 tell > > the width (00 = 32bit, 10 = 64bit). > > I don't know if this is a shure indicator. > > Doesn't this just mean that it can be the target for a DAC > transaction? That's not the same thing as being a master. Yes, but that's the best that I could find in the specs. The exact information seems to be chip specific so it's left to the driver and the bridges between. PCI-PCI bridges are well defined. The 2105x specs don't mention DAC - maybe the newer 2115x can. > Our older Myrinet cards have a 32-bit memory base, but can be a 64-bit > busmaster. (ie, are what I consider to be DAC capable). But maybe > they are not typical.. I have no clue. > > But there are cards that definitive can't without replacement. > > E.g. USB OHCI controllers are defined with 32bit DMA registers. > > I don't use USB on my alpha ;) Me too, but I do tests on alpha. > My concern is that at least one cheap NIC, and one cheap SCSI > controller is DAC capable. I don't think anything else is really > critical. If we had that, and we could made busdma DAC aware, and we > got the chipset goo right, we'd have an alpha which could be used with > 2GB. Mmm... sym defines nc_dnad64 in a header but it's not used anywhere. -- B.Walter BWCT http://www.bwct.de ticso@bwct.de info@bwct.de
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