Date: Wed, 18 Jun 2003 12:59:16 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: ticso@cicely.de Cc: freebsd-alpha@freebsd.org Subject: Re: 5.1beta2 on Alpha ES40 w/ 32GB pys ram Message-ID: <16112.39524.638824.307800@grasshopper.cs.duke.edu> In-Reply-To: <20030618120004.GG3626@cicely12.cicely.de> 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>
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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. 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.. > 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 ;) 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. Drew
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