How to Convert Legacy Kernel Modules for modern Kernels

[Tianrui Wei]

On 21 Jan 2022, at 16:53, Greg KH wrote:

> On Fri, Jan 21, 2022 at 04:21:18PM +0800, Tianrui Wei wrote:
>>>> If there're not out of box solutions, is there a way I could view the
>>>> API changes in every subsystem clearly? For example, this particular
>>>> commit[^1] shows the second return argument is being removed from
>>>> ki_complete, and it took a lot of fishing down the lkml to do. Perhaps
>>>> there is a simpler way?
>>>
>>> Use git itself to track the changes in apis.  You can see all changes to
>>> a .h file by doing:
>>>     git log -p path/to/file
>>> and then see where the api got changed.
>>
>> This is a really good suggestion, and it's also the way I approach
>> recent kernel modules. However some specifically ancient kernel
>> modules is rather difficult to use this approach.
>
> We have git history going back to Linux 0.1 so this should work.  If
> not, then do the normal 'does it build' test.  APIs are almost always
> changed in ways that break the build.

Thanks for the suggestion, I'll bear it in mind.

>
>>> It usually isn't that difficult to forward port a driver, but it all
>>> depends on the age of the code, and what it actually does.  Do you have
>>> a link to the code you wish to drag forward?
>>
>> The specific driver I had in mind is a PCIE driver for a Xilinx IP
>> block. It's under
>> https://www.xilinx.com/products/boards-and-kits/ek-k7-kc705-g.html#resources
>> in a zip folder called rdf0281-kc705-base-trd-2014-3.zip. Everyone
>> with a xilinx account could download the folder. Unfortunately its
>> header claims it contains confidential information from Xilinx, as
>> such I'm a bit wary to post it online.
>
> Please get support from xilix for stuff like this.  You are paying for
> it from them, so please take advantage of it.  Especially if they claim
> that their code is not GPLv2 compatible, you want them to take that
> legal risk, not you :)

Thanks! That makes a lot of sense.

>
> greg k-h

Best Regards,
Tianrui