Messages in this thread | | | Date | Sat, 23 Jan 1999 13:46:49 +0100 (MET) | From | Geert Uytterhoeven <> | Subject | Re: why is vesafb not a module? |
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On Fri, 22 Jan 1999, Brian Gerst wrote: > 91b59e21456b337c213e7290c93f43a8@interlinx.bc.ca wrote: > > Wow, my second posting in two days. As I have not yet subscribed to the > > list can I as that you CC me (yup to that horrifyingly ugly from > > address) on any responses. > > > > I am wondering why the vesafb (VESA Frame Buffer device) is not a > > module? I like building stripped down kernels (even to the point of > > putting my load time devices into an initrd ramdisk) that I can run on a > > variety of machines. I have some machines that use the Matro frame > > buffer framebuffer device but others that use the standard VESA frame > > buffer. > > Because the VESA framebuffer uses the VESA 2.0 BIOS, it can only be > called from real mode. Therefore, it must be done at boot time, before > the kernel enters protected mode. This means that it cannot be compiled > as a module (unless somebody wants to hack vm86 support so that it can > be used _inside_ the kernel).
This is not completely true: it's not vesafb that calls the VESA 2.0 BIOS, but the very early boot code before the kernel is booted.
So in theory you could make vesafb a module, but then you wouldn't get any screen output until vesafb is loaded.
Greetings,
Geert
-- Geert Uytterhoeven Geert.Uytterhoeven@cs.kuleuven.ac.be Wavelets, Linux/{m68k~Amiga,PPC~CHRP} http://www.cs.kuleuven.ac.be/~geert/ Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium
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