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[directfb-dev] Re: Video overlay questions
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[directfb-dev] Re: Video overlay questions

Quoting Andreas Robinson (
> Michel Dänzer wrote:
> > /dev/cle266vgaio can very well exist without the kernel module, in
> > particular if /dev isn't mounted as devfs. If you at least opened it and
> > verified that it behaves as expected...
> I do that too. The device is opened and mmapped in driver_init_driver(). I
> know there is a function for this in DirectFB, but this way I can ask the
> hardware where the IO registers are in the physical memory space, instead of
> assuming that they are right behind the framebuffer.

The IO space isn't right behind the framebuffer, it's just a hack to tell
the fbmem.c's mmap function to map the registers intead of the framebuffer.
Framebuffer drivers can provide their own mmap function to expose further

> At any rate, this is just a stopgap solution until a real framebuffer device
> is developed. When that happens, changes to the DFB driver will be minimal.

I already ported the XFree86 drivers for Savage, NeoMagic and VMware to fbdev.
So it wouldn't be that difficult for me to write an fbdev driver without lacking
any feature of the original driver.

If you want to start writing it yourself you should have a look at neofb.
I think it's a clean example for an fbdev driver.

> Off topic: Btw, isn't the framebuffer becoming somewhat of a shared
> resource? Wouldn't it be appropriate with a memory manager for it, in the
> DRM module perhaps?

Are you talking about allocation of buffers within the framebuffer memory?
This is done by DirectFB's surface manager (src/core/surfacemanager.c).

Or are you thinking about dynamic allocation of physical memory,
i.e. variable framebuffer size in shared memory environments?

Best regards,
  Denis Oliver Kropp

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