Re: vesafb on archs !ia32 [Re: Calling VESA BIOS routines from kernel?]
Egbert Eich (eich@hilbert.ikp.physik.tu-darmstadt.de)
Sun, 19 Dec 1999 10:48:08 +0100 (MET)
David Woodhouse writes:
>
> eich@hilbert.ikp.physik.tu-darmstadt.de said:
> > Why can't we turn on/switch the thin on run time? Have a simple
> > utility execute the bios call from user space and then inform vesafb
> > of the new paramters. But please: no IA32 emulator in the kernel!
>
> A fine plan. This would also allow us to use the vesafb code on other
> architectures - all we need is a tool which can use the X4.0 loadable modules
> to set up a linear framebuffer mode, then tell the kernel about it.
>
We (Xfree86) had a similar idea, too. It doesn't make much sense
to build different drivers for the same chipset considering the
limited number of really experienced driver people. Even if one
project uses code from another project as example it is still a
lot of work.
However there are a problem: Xfree86 4.0 has departed from the
low level driver model 3.3 uses: Instead of passing a huge structure
to the midlevel code to infor it of the properties of the lowlevel
driver - which needs to get extended whenever new features get
added to the server - the driver does a lot of initialization
itself by calling the approprate functions.
If for example the driver supports acceleration for 24bpp it
will call the initialization functions for that when 24bpp is
requested.
With this model we have a lot of Xserver specific setup calls
in the driver which other systems don't require or require
differnetly.
Regards,
Egbert.
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