ThinkPad i1300, XF86Config, extern_disp and a tale of two kernels

From: Madhusudan Singh (
Date: 09/08/03

Date: Sun, 07 Sep 2003 18:15:27 -0400


        I have two different kernel on my machine :

        1. 2.4.20-8 (Vanilla kernel shipped with RH 9).
        2. 2.4.21 (custom compiled kernel with acpi patch and IRQ's allocated with

        The XF86Config being the same with both, I notice the following behaviour :

1 - > Use of Fn-F7 allows me to switch between external monitor, external
monitor+own monitor and own monitor modes, as should be.

2. -> Use of Fn-F7 does nothing. If I boot with external monitor connected,
only the external monitor works, otherwise only the laptop's own monitor

        I have heard that the BIOS sets this thing up in some fashion, but since I
use ACPI subsystem to assign IRQ's in the 2nd case, I can presumably not
use that. Is there some way I could mimic the behaviour of configuration 1
with configuration 2 ?