Making a module 2.4 compatible

Making a module 2.4 compatible

[James Lamanna]

I have a kernel module for a robot that was developed for
the 2.0 and 2.2 kernels and does not work under 2.4.
Unfortunately, the company that made it is not in business anymore.
It would be nice to have it working under 2.4, so is there someplace
that outlines some of the major things that would have changed so I can
update the module accordingly?

Thanks,
--James Lamanna

Re: Making a module 2.4 compatible

[Horst von Brand]

James Lamanna <jlamanna@its.caltech.edu> said:
> I have a kernel module for a robot that was developed for
> the 2.0 and 2.2 kernels and does not work under 2.4.
> Unfortunately, the company that made it is not in business anymore.
> It would be nice to have it working under 2.4, so is there someplace
> that outlines some of the major things that would have changed so I can
> update the module accordingly?

Seconded! There are a few users of iBCS around here, who _need_ the
functionality and don't get it with 2.4.x (in this case, Red Hat 7.1). Or
is there a replacement for it?

Thanks!
-- 
Horst von Brand                             vonbrand@sleipnir.valparaiso.cl
Casilla 9G, Vin~a del Mar, Chile                               +56 32 672616

Re: Making a module 2.4 compatible

[Christoph Hellwig]

Hi Horst,

In article <200106241713.f5OHDItV000540@sleipnir.valparaiso.cl> you wrote:
> Seconded! There are a few users of iBCS around here, who _need_ the
> functionality and don't get it with 2.4.x (in this case, Red Hat 7.1). Or
> is there a replacement for it?

Take a look at inux-abi:

  http://linux-abi.sourceforge.net
  ftp://ftp.openlinux.org/pub/people/hch/linux-abi

Re: Making a module 2.4 compatible

[Anthony Barbachan]

----- Original Message -----
From: "Christoph Hellwig" <hch@ns.caldera.de>
To: "Horst von Brand" <vonbrand@sleipnir.valparaiso.cl>
Cc: <linux-kernel@vger.kernel.org>
Sent: Monday, June 25, 2001 11:53 AM
Subject: Re: Making a module 2.4 compatible


> Hi Horst,
>
> In article <200106241713.f5OHDItV000540@sleipnir.valparaiso.cl> you wrote:
> > Seconded! There are a few users of iBCS around here, who _need_ the
> > functionality and don't get it with 2.4.x (in this case, Red Hat 7.1).
Or
> > is there a replacement for it?
>
> Take a look at inux-abi:
>
>   http://linux-abi.sourceforge.net
>   ftp://ftp.openlinux.org/pub/people/hch/linux-abi

    I've tried linux-abi myself.  No luck at all.  Best I can tell it has
yet to reach the level of compatibility that iBCS has.  Although last
version I tried was the 2.4.3 patch on the linux abi web site.  I noticed a
newer one on the openlinux ftp site, might give that one a try too though
considering what happened with the one I previously tried I am nowhere near
optimistic.  Unfortunately this has burned me since I need to setup a new
system that uses the new features of the 2.4.x kernels (latest rieserfs,
better smp, support for the latest ide chipsets, better scaling) which also
can run SCO binaries.  I am actually at the point where I am strongly
considering trying to port iBCS myself though not sure about it yet mainly
due to concerns that I may not implement it correctly to work with some of
the latest kernel changes without understanding how the original iBCS was
designed.

    By the way is there a reason there isn't a patch to support the latest
available for the 2.2.x kernels?  Is it incompatible with the 2.2.x kernels?
I recently needed to downgrade the kernel on a machine due to 2.4.x
instability but was unable to due to the lack of a patch to support the
latest rieserfs on 2.2.x.

Re: Making a module 2.4 compatible

[Timur Tabi]

** Reply to message from James Lamanna <jlamanna@its.caltech.edu> on Sat, 23
Jun 2001 22:10:58 -0700


> It would be nice to have it working under 2.4, so is there someplace
> that outlines some of the major things that would have changed so I can
> update the module accordingly?

Unfortunately, no.  But if it turns out I'm wrong, please let me know what you
find.


-- 
Timur Tabi - ttabi@interactivesi.com
Interactive Silicon - http://www.interactivesi.com

Re: Making a module 2.4 compatible

[Richard B. Johnson]

On Mon, 25 Jun 2001, Timur Tabi wrote:

> ** Reply to message from James Lamanna <jlamanna@its.caltech.edu> on Sat, 23
> Jun 2001 22:10:58 -0700
> 
> 
> > It would be nice to have it working under 2.4, so is there someplace
> > that outlines some of the major things that would have changed so I can
> > update the module accordingly?
> 
> Unfortunately, no.  But if it turns out I'm wrong, please let me know what you
> find.
> 

As a start:

wait_queue_head_t	Now defined.
You can do '#if !defined(...)` and make code changes backwards compatible.


Macro, THIS_MODULE	is now the first member of struct file_operations.


Include <linux/init.h>	__init data type for one-time initialization code
			or data.
This is new, hense not backwards compatible.


Explicit initialization of spin-locks, SPIN_LOCK_UNLOCKED and/or
			spin_lock_init(spinlock_t *);
If you fix this, it's backwards compatible.


ioremap() and friends is now required even for low memory stuff.
You can no longer access this with a simple pointer, you must
use readl()/writel(), etc., for proper defererence. If you fix
this, it's backwards compatible.


These changes should get your module to compile (or nearly so).

Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).

"Memory is like gasoline. You use it up when you are running. Of
course you get it all back when you reboot..."; Actual explanation
obtained from the Micro$oft help desk.

Re: Making a module 2.4 compatible

[Jonathan Corbet]

> It would be nice to have it working under 2.4, so is there someplace
> that outlines some of the major things that would have changed so I can
> update the module accordingly?

<BlatantSelfPromotion>

Within a week or so, "Linux Device Drivers" second edition should hit the
shelves.  It will also hit the net, but that's going to take a little
longer.  If it doesn't answer all your questions, then we failed to achieve
what we set out to do.

</BlatantSelfPromotion>

jon

Jonathan Corbet
Executive editor, LWN.net
corbet@lwn.net