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Date:      Thu, 06 Jun 2002 08:03:06 -0700
From:      Terry Lambert <tlambert2@mindspring.com>
To:        Andrew Gallatin <gallatin@cs.duke.edu>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: allocating memory
Message-ID:  <3CFF79AA.8D469BA0@mindspring.com>
References:  <3CFEEB99.AEDC5DB9@math.missouri.edu> <3CFF2780.FAD81226@mindspring.com> <20020606122702.A81113@energyhq.homeip.net> <3CFF4FE8.86C44C31@mindspring.com> <15615.25973.556463.119216@grasshopper.cs.duke.edu>

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Andrew Gallatin wrote:

[ ...Alpha 2G memory limit... ]

> The only known problem is nearly all PCI network drivers don't use
> busdma (disk controllers already use busdma).  If you're willing to
> use a crappy ISA nic which either uses busdma or just does PIO, you
> should be fine.
> 
> (newer alphas also have a "monster window" for 64-bit pci dma; we
> don't use this currently)
> 
> I've never been motivated to work on this because none of the alphas
> in my care have ever had more memory than the direct mapped DMA window
> size. (2GB some places, 1GB other places).

Yep.  That's the problem in a nutshell.  I have the same lack of
motivation (and significantly less memory, and only one Alpha box).

I was unaware of the "monster window".  It makes sense (like the
Serverworks board that can do the DMA to banked PAE pages by
using the physical address on the bus side of things).

Unfortunately, Alpha has pretty much been murdered in the night by
people who would rather kill it than keep up with it.  8-(.


> The sparc64 guys had the (good?) fortune of having to write a driver
> for the most common nic on their platform, so they did it right.

Actually...

You ought to post a "Junior Kernel Hacker Task".  You might get a
bite on it (you never know).  There have to be universities with
some aging Alpha hardware and some students who are there to
actually learn, rather than just there to get their union card...

-- Terry

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