Subject: Re: ISA direct config of ACPI devices
To: Jared D. McNeill <jmcneill@invisible.ca>
From: Matthias Drochner <M.Drochner@fz-juelich.de>
List: tech-kern
Date: 11/23/2007 19:21:21
jmcneill@invisible.ca said:
> LPC is physically different from ISA

Just had a look at the datasheets: Is is physically
different indeed, multiplexed/serialized, and it
runs at PCI speed.

> but looks like ISA from a software perspective

Mostly, but there are differences which can be important:
-uses 32 address bits instead of 24
-can busmaster DMA w/o the ISA DMA controller
-uses a serial interrupt protocol which does more than
 the 15 ISA interrupts, so one can't assume a 1:1 relationship
 between LPC interrupts and 8259 inputs

best regards
Matthias




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