[uClinux-dev] framebuffer/console question

Geert Uytterhoeven geert at linux-m68k.org
Thu Sep 20 15:19:06 EDT 2012

Hi Angelo,

On Mon, Sep 17, 2012 at 2:29 PM, angelo <angelo70 at gmail.com> wrote:
> i have a working coldfire board, running uClinux. I connected a 128x64
> monochrome lcd on gpio, and written a framebuffer driver.

On gpio, so it's not memory mapped?

> From userspace i can now write on "/dev/fb0" and see some images properly.


> My question now is about console. Just for playing, i am trying to see the
> console output on the LCD. Even if very small, this should be possible, as i
> enabled the "console framebuffer" driver and some fonts.


> Once i booted linux, i try an echo "test" > /dev/console, something seems to
> happen on the screen, some pixels are cleared, but i don't see nothing
> similar to font chars.


> I read fb and fbcon docs, but i couldn't find any document that explain if
> console fb driver (fbcon) can be used with some fb drivers only (like
> vesfb), or with any fb driver. So my question is: is it possible or i should
> add/create some additional driver ?

The console should work, assumed you provided the proper drawing operations
in your struct fb_ops. E.g. for simple packed monochrome:

        .fb_fillrect            = cfb_fillrect,
        .fb_copyarea            = cfb_copyarea,
        .fb_imageblit           = cfb_imageblit,



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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