Re: framebuffer

["Ambar Roy" <ambarroy@xxxxxxxxx>]

> Thanx again.Ya ur answer has raised some issues.Now let me verify whether
my
> understanding of frame buffer is right.Every Video card has a frame
buffer.A
> frame buffer is nothing but the video memory.Normally u require the driver
> for supporting some extra features
> of the card like hardware acceleration,etc.Now since we are bypassing this
> and writing directly to the video memory(Frame buffer)we cannot use any of
> the special features of the card.This gives us a normal VGA
functionality.
>The frame buffer mode must be  enabled at boot up so that Linux in real
mode
>  shifts to directly wriitng on  to the VideoRAM,instead of going via a
driver.
> Any good links abt how Linux  writes on to the  framebuffer ,etc.
There is one ambiguity here.. when u r using a driver for your card inside
the x server, then the driver is responsible for setting up the framebuffer
and video modes and to write to this framebuffer (if required)! When u use
the kernel framebuffer mode, u effectively move this video driver from the x
server to the kernel. The framebuffer interface provided by the kernel is
thus something like a universal video driver interface! I don't know the
exact details of the linux kernel framebuffer interface and how it is used
with x servers. The main thing is (again i say this!!!) the framebuffer from
the kernel is just a name for a interface to the video drivers inside the
linux kernel(which might just give u a framebuffer to write to, though
frankly, i don't know abt that!) To know more abt the kernel framebuffer i
guess u cud read the docs in yr /usr/src/linux/Documentation/fb!

Bye,
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