Help with debugging of a framebuffer driver on a legacyfree system.

Hi there

As part of a project I am trying to write a framebuffer device driver for a graphic chip. Up until now I have compiled my code as a module and been doing insmod, rmmod and that have worked nicely.

I then tried to compile the driver into the kernel but that makes the kernel hang. As my development system are a legacy free laptop and my driver initializes the screen, the kernel hangs without me being able to figure out where and why that happend.

So I seek advice on how to debug the driver! As said, the laptop are legacy free, so I have not got a serial port. I have tried a usb->serial adapter, but that requires a driver. Can I do USB->USB on another computer? Or?

Or am I stuck with coding my own printk variant and writing to the screen or is there any other option I have not thought of?

Regards Thomas, Denmark

On Wed, 27 Aug 2003 16:20:35 +0200 "Thomas S. Iversen" <[email protected]> wrote:

| Hi there 
| 
| As part of a project I am trying to write a framebuffer device
| driver for a graphic chip. Up until now I have compiled my
| code as a module and been doing insmod, rmmod and that have worked
| nicely.
| 
| I then tried to compile the driver into the kernel but that
| makes the kernel hang. As my development system are a legacy
| free laptop and my driver initializes the screen, the kernel
| hangs without me being able to figure out where and why that
| happend.

First choice would be to develop on a system where you can add (PCI?) bus probes or other adapters/gadgets, like a port-80 card.

| So I seek advice on how to debug the driver! As said, the
| laptop are legacy free, so I have not got a serial port. 
| I have tried a usb->serial adapter, but that requires a driver.
| Can I do USB->USB on another computer? Or?
| 
| Or am I stuck with coding my own printk variant and writing to the
| screen or is there any other option I have not thought of?

There are already early_printk patches and an x86-specific "poke a character into video RAM" patch. The latter one is at:
http://kernelnewbies.org/documents/videochar.txt

--
~Randy