memory mapping (was: '386 Unix Wars)

[Marco S Hyman]

In article <2732 at sixhub.UUCP> davidsen at sixhub.UUCP (bill davidsen) writes:
    
      Let me ask a question here, based on something I partially remember
    from setting up ISC some months ago... There was a table which defined
    memory, and we used it to define memory which could not do DMA, to force
    the o/s to fake it. I *thought* I read in the description of that table
    that it could also be used to block out a section of RAM to keep the o/s
    from using it, but to still use RAM *above* the reserved space.

There is a MEMRANGE entry in /etc/default boot.  Mine looks like (386/ix
2.0.2)

	MEMRANGE=0-640K:0,1M-15M:0,16M-15M:1

Note that the last entry (16M-15M:1) is in reverse order.  This tells the OS
to scan from the top down when looking for memory in this range.  The :1
says DON'T use DMA for this range.

I forget where it's documented, maybe someone else can say where in TFM to
look.

// marc
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// marc at dumbcat.sf.ca.us
// {ames,decwrl,sun}!pacbell!dumbcat!marc