# framebuffer driver and KMS radeon.

## mathfeel

My machine used to boot up with fbsplash and turns on console decoration with the uvesafb driver.  I did not enable the KMS option for the radeon driver (the chip is R500), but basically uvesafb as framebuffer driver and radeon as X driver works.

Now I decided to play with enabling KMS for radeo. So I turned off framebuffer driver (FB_UVESA=n and FB_RADEON=n) in kernel and modified boot option to be simply

```
vmlinuz root=/dev/sda1 ro quiet splash
```

 Now when I reboot, the screen is black, but everything starts up fine in the background.  Finally when X is started by gdm, then X takes over the display.  I cannot CTRL-ALT-F# out to any of the console.

What am I screwing up here?

----------

## chithanh

Black screen usually points to framebuffer console not enabled in kernel (or if built as module, not loaded).

----------

## mathfeel

 *chithanh wrote:*   

> Black screen usually points to framebuffer console not enabled in kernel (or if built as module, not loaded).

 

Thanks, somehow I thought with:

```
CONFIG_DUMMY_CONSOLE=y

CONFIG_FRAMEBUFFER_CONSOLE=m

CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY=y

CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
```

the module would be loaded when the fbcondecor service start. Compiling it in kernel works.

I just noticed also now that CONFIG_FB_CON_DECOR option is missing! What?

----------

## sera

```

CONFIG_DRM_RADEON=y

CONFIG_DRM_RADEON_KMS=y

CONFIG_FB_RADEON=y

CONFIG_FB_RADEON_I2C=y

CONFIG_FB_RADEON_BACKLIGHT=y

# CONFIG_FB_RADEON_DEBUG is not set
```

is the relevant part.

----------

## VoidMage

@sera: not really, 'CONFIG_FB_RADEON=y' would make KMS

fail to work.

----------

## mathfeel

 *VoidMage wrote:*   

> @sera: not really, 'CONFIG_FB_RADEON=y' would make KMS
> 
> fail to work.

 

Exactly.

Turned out my problem was unrelated because I already have FB_RADEON=n.  I found that the following conditions has to be true for CONFIG_FB_CON_DECOR to appear in menuconfig:

```
CONFIG_FB_TILEBLITTING=n

CONFIG_FB=y (not m)

```

After that and enabling CONFIG_FRAMEBUFFER_CONSOLE and CONFIG_FB_CON_DECOR, things are working now.

----------

## sera

 *VoidMage wrote:*   

> @sera: not really, 'CONFIG_FB_RADEON=y' would make KMS
> 
> fail to work.

 

this is a grep -i radeon of my running kernel 2.6.34 with enabled and working kms on a rv560, thats all I can say.

----------

## VoidMage

Well, it's just like having both IDE and libata drivers enabled 

for your controllers - sometimes it works, but on occasions,

you'll be getting "unexpected" failures.

----------

## sera

 *VoidMage wrote:*   

> Well, it's just like having both IDE and libata drivers enabled 
> 
> for your controllers - sometimes it works, but on occasions,
> 
> you'll be getting "unexpected" failures.

 

I removed the radeon fb and it still works  :Smile: 

----------

