Subject: Re: ISA direct config of ACPI devices
To: Jared D. McNeill <>
From: David Laight <>
List: tech-kern
Date: 11/23/2007 20:44:21
On Fri, Nov 23, 2007 at 03:34:43PM -0500, Jared D. McNeill wrote:
> On Fri, 23 Nov 2007, Joerg Sonnenberger wrote:
> >In theory yes. In practise just look how many ICH6 style notebooks are 
> >sold where the BIOS doesn't include HPET in the DSDT...
> This isn't quite what I meant.. how do you setup DMA without either 
> talking directly to the southbridge, or using the ISA registers? To my 
> knowledge there isn't a method to do this via AML methods.

On an i386/i486 system you can set one of the motherboard DMA channels
into 'cascade mode'.  Then the ISA peripheral is responsible for putting
the address out onto the ISA bus.
However I'm not at all certain than any modern systems support this.
Cards like the amd pcnet-isa (can) work that way.


David Laight: