Mailinglist Archive: opensuse-kernel (68 mails)

[Jean Delvare <jdelvare@xxxxxxx>]

On Monday 05 July 2010 06:25:51 pm Greg KH wrote:
> On Mon, Jul 05, 2010 at 10:38:12AM +0200, Ole Streicher wrote:
> > Hi,
> >
> > is it possible to disable the built-in 8250 driver of the recent
> > (11.2) kernels from the boot command line?
> >
> > Reason: I need to use a specific serial I/O board (Meilhaus ME
> > 9100) that requires a patched 8250.c file to work (see
> > http://www.meilhaus.de/fileadmin/upload/download/products/serial/me
> > 9x00-2.0.3-2.6.28.patch for the patch, and
> > http://www.spinics.net/lists/linux-serial/msg01650.html for a short
> > discussion on the LKML).
>
> As the de-facto serial kernel maintainer now, I'd be glad to accept
>  this patch if it is fixed up as per the review comments in that
>  thread.
>
> If that happens, then you would not need to worry about this type of
> issue.
>
> Also, if you are having to patch the file anyway, you are building
>  your own kernels, right?

Not necessarily. Drivers can easily be built outside of the kernel tree, 
and I bet this is what the original poster is doing.

>  Then you shouldn't have to worry about
>  building the driver into the kernel, right?

It shouldn't be a problem either way, assuming that serial port follow 
the standard device driver model. Even if the "wrong" driver is built 
into the kernel, you should be able to:
* Unbind the driver in question from the devices, using the "unbind" 
attributes in sysfs.
* Build your modified driver as a module, with a different name 
(driver.name field).
* Load your new module, and either let it bind automatically to the 
devices, or use the sysfs "bind" attributes.

(This is all said without having looked at the specific implementation 
of the serial subsystem... Maybe there are extra complexities I'm 
missing.)

-- 
Jean Delvare
Suse L3
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