Date: Tue, 22 Dec 1998 16:36:20 +0000 From: Mark Templeton <druid@atc.dera.gov.uk> To: Mike Smith <mike@smith.net.au> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Memory holes for ISA device drivers Message-ID: <367FCA84.3DBE8085@atc.dera.gov.uk> References: <199812141110.DAA00438@dingo.cdrom.com>
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Mike Smith wrote:
>
> > OS is 2.2.5
> > Card is on ISA bus, preferably at 0xA00000.
> >
> > How do I create a (physical) memory hole for a card,
> > as the card holds 64k shared memory?
> > The target system BIOS does not support the 15-16M memory hole.
> > pmap_mapdev() maps physical to virtual memory, but does not
> > create a hole.
> >
> > How do I create a memory hole?
>
> This is chipset- and motherboard-specific. If you can't map the card
> into the ISA 'hole' at 0xa0000, then you're SOL short of building a
> custom PCI:ISA bridge (eg. using a PLX9050) and remapping it into PCI
> space.
Thank you for your comments, Mike.
But even on systems that support the ISA memory hole, this
restricts FreeBSD to effectively see only 15MB of RAM.
Surely this is undesirable?
Are there no software alternatives?
If not, then I guess I have to talk to MRBIOS and see if they
can supply me a BIOS which will do what I need.
Mark.
--
0 00000000 0
0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0
0 0
0 The Druid 0
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