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Date: Tue, 14 Oct 1997 14:18:38 -0700
From: "Fred L. Templin" <templin@erg.sri.com>
To: freebsd-hackers@freebsd.org, mike@smith.net.au
Cc: templin@erg.sri.com
Subject: Re: pccard driver questions (FreeBSD 2.2.2-RELEASE + PAO-970616)
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> > You could map a larger window; that'd certainly be better.  TBH I 
> > haven't checked to see if there is a limitation that would prevent you 
> > from having a 96kB window for your card.
> 
> This would be nice, but I'm somewhat skeptical it will be possible. I'll
> certainly check into it with an optimistic viewpoint, however.

Unfortunately, the above does not seem to be an option. From the
file 'sys/pccard/i82365.h':

> /*
>  *      The memory window registers contain the start and end
>  *      physical host address that the PCIC maps to the card,
>  *      and an offset calculated from the card memory address.
>  *      All values are shifted down 12 bits, so allocation is
>  *      done in 4Kb blocks. Only 12 bits of each value is
>  *      stored, limiting the range to the ISA address size of
>  *      24 bits. The upper 4 bits of the most significant byte
>  *      within the values are used for various flags.
>  *
>  *      The layout is:
>  *
>  *      base+0 : lower 8 bits of system memory start address
>  *      base+1 : upper 4 bits of system memory start address + flags
>  *      base+2 : lower 8 bits of system memory end address
>  *      base+3 : upper 4 bits of system memory end address + flags
>  *      base+4 : lower 8 bits of offset to card address
>  *      base+5 : upper 4 bits of offset to card address + flags
>  *
>  *      The following two bytes are reserved for other use.
>  */

So, it looks like the 4KB per-window limit is an artifact of the
controller chip's  register organization. Again, please someone let
me know if I'm missing something...

Fred
templin@erg.sri.com