Re: holes for ISA boards...

Alan Cox (alan@lxorguk.ukuu.org.uk)
Sat, 12 Jun 1999 12:48:45 +0100 (BST)


> embedded system... Unfortunately, the board is ISA, and maps its memory into
> IO space starting at 12MB -- which according to the epson docs means
> that system memory is limited to 12MB. However, the epson docs also

It does

> assume you're using an operating system for which the source is
> proprietary... I figured I could somehow put a "hole" by manipulating
> page flags, and came up with the following:

No. You need to put a hole in physical space. You actually need to turn off
some of RAM and things, You will also need a chipset that bothers to decode
all memory above RAM strictly as ISA/PCI and isnt just saying "below 1Gig is
ram, cos the bios knows that too" or similar.

> Any idea what's going on? Is it impossible for me to poke a hole in memory
> from 12-16MB so I can hack on this silly ISA board?

Consult the chipset documentation. You've got the kernel hole right I think,
now you need to do the hardware hole

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