Framebuffer as a module

Framebuffer as a module

[-=da TRoXX=-]

Hello,

please CC me on any replies to this message since I'm not subscribed to the
list (just toooo much mail for me)

I have a very simple question:
I used to compile-in my framebuffer-device in the kernel
then i just appended "video=tdfxfb:1024x768-32@70" in lilo.conf and it
worked..

now i compiled it as a module, and want modprobe to start it up for me..
how can this be done?
modprobe tdfxfb 1024x768-32@70
won't work, because there is no '=' sign in it so modprobe doesn't recognize
it as a parameter, and doesn't pass it.

so what can i do about it?

tnx in advance :)



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Re: Framebuffer as a module

[Keith Owens]

On Fri, 5 Jan 2001 18:52:45 +0100, 
"-=da TRoXX=-" <TRoXX@LiquidXTC.nl> wrote:
>I have a very simple question:
>I used to compile-in my framebuffer-device in the kernel
>then i just appended "video=tdfxfb:1024x768-32@70" in lilo.conf and it
>worked..
>
>now i compiled it as a module, and want modprobe to start it up for me..
>how can this be done?
>modprobe tdfxfb 1024x768-32@70
>won't work, because there is no '=' sign in it so modprobe doesn't recognize
>it as a parameter, and doesn't pass it.

A quick look at drivers/video/tdfxfb.c shows a complete lack of
MODULE_PARM entries so modprobe/insmod will not let specify any
parameters.  Ask the tdfxfb author to add this feature, or code it
yourself.

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Re: [PATCH] VESA framebuffer w/ MTRR locks 2.4.0 on init

[Alan Cox]

> 1)  The amount of video memory is being incorrectly reported my the VESA call
> used in arch/i386/video.S (INT 10h AX=4f00h).  My Dell Inspiron 3200 (NeoMagic
> video) returns that it has 31 64k blocks of video memory, instead of the
> correct 32.  This means that vesafb thinks that I've got 1984k of video ram,

You have 31. The last one is used for audio buffering

> 2)  When the vesafb goes to mtrr_add its range (with the incorrect 1984k size)
> mtrr_add fails with -EINVAL.  The code in vesafb_init then goes into a while
> loop with no exit, as each size mtrr fails.
>                  while (mtrr_add(video_base, temp_size, MTRR_TYPE_WRCOMB,
> 1)==-EINVAL) {
>                          temp_size >>= 1;
>                  }

Ok that one is the bug.

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Re: [PATCH] VESA framebuffer w/MTRR locks 2.4.0 on init

[David Wragg]

Alan Cox <alan@lxorguk.ukuu.org.uk> writes:
> > loop with no exit, as each size mtrr fails.
> >                  while (mtrr_add(video_base, temp_size, MTRR_TYPE_WRCOMB,
> > 1)==-EINVAL) {
> >                          temp_size >>= 1;
> >                  }
> 
> Ok that one is the bug.

Even with the obvious bug fixed, that code is strange.  "temp_size >>=
1" does little to improve the chances of the mtrr_add succeeding.
Something like this would be better:

if (mtrr_add(video_base, temp_size, MTRR_TYPE_WRCOMB, 1) == -EINVAL) {
        /* Find the largest power-of-two */
        while (temp_size & (temp_size - 1))
                temp_sze &= (temp_size - 1);

        mtrr_add(video_base, temp_size, MTRR_TYPE_WRCOMB, 1);
}


(But this is just a very crude way to work around the inflexibility of
the MTRRs.  Rather than cluttering up calls to mtrr_add, it would be
better to fix this properly, either by implementing PAT support
(Zoltán Böszörményi said he was working on that), or by having a
user-space helper program to make more intelligent MTRR allocations,
or both.)


David Wragg
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Re: Framebuffer as a module

[Bryan Mayland]

> I used to compile-in my framebuffer-device in the kernel
> then i just appended "video=tdfxfb:1024x768-32@70" in lilo.conf and it
> worked..
> now i compiled it as a module, and want modprobe to start it up for me..
> how can this be done?
> modprobe tdfxfb 1024x768-32@70

That's a very good question.  The tdfxfb module has no parameters.  It would be
ideal if the tdfxfb mainatiner would add some MODULE_PARM lines for all the
parameters and move the code from tdfxfb_setup that does work into tdfxfb_init.

I think a valid work-around for you is to use fbset after you load the module
to set the resolution.  Does that work?
Bry

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Re: Framebuffer as a module

[Bryan Mayland]

-=da TRoXX=- wrote:

> and i don't get it, who accepts these parameters in the kernel then? i mean
> if i put them in lilo.conf at least SOME thing uses them to set the
> framebuffer right...

    The tdfxfb code does.  When compiled into the kernel, there is a function
(tdfxfb_setup) which the kernel calls with the relevant kernel command-line
parameters.  When compiled as a module, this function is ifdef'ed out, as well
it should be, because I don't think that there is a function which is called to
pass the module parameters.  Modules use MODULE_PARM to 'import' their
parameters.  The code is incomplete, perhaps for a reason.  In theory, the
author should add the required MODULE_PARM macros to export the parameters and
then move the code which does anything besides saving the paramter values to
tdfxfb_init, which is called when the module is loaded /and/ after tdfxfb_setup
when compiled into the kernel.  I don't have the time to fix it myself, I don't
even have a machine with Linux and a Voodoo3 card.

> I know this parameter is for modules only that support modedb (modedb.c) but
> tdfxfb supports that(that's why it works in the kernel)...

    It does, but only when compiled into the kernel due to the way it does its's
setup.

Bry

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