Linux kernel compatability

Alexander Leidinger Alexander at Leidinger.net
Wed Jan 5 10:18:25 UTC 2011


Quoting David Xu <davidxu at freebsd.org> (from Wed, 05 Jan 2011 17:56:18 +0800):

> Alexander Leidinger wrote:
>> Quoting Jeff Roberson <jroberson at jroberson.net> (from Tue, 4 Jan  
>> 2011 13:13:00 -1000 (HST)):
>>
>>> After this discussion I'm leaning towards leaving the layer I have  
>>> in the ofed/ directory and leaving it tied to the version of ofed  
>>> we currently have imported.
>>
>> To give you one more little argument in favour of this: copies in  
>> SVN are cheap. If there is the need to have the compat shim  
>> available for something else, it can be put into another place later.
>>
>> On a somewhat related area: now that you've done this huge compat  
>> work you have a very good idea which parts correspond to what in  
>> the other OS. It would be great if this could be documented  
>> somewhere (wiki?) in a way that people which are interested to  
>> write a FreeBSD native driver just need to have a look at some  
>> pages to be able to see what linux stuff they have to change in  
>> which way to get a big part of the porting covered. IMO this would  
>> also help in reviewing and verifying the correctness of your  
>> current work (and as such would be beneficial to the sponsors of  
>> this work), as people could see if you missed some semantic  
>> differences or overlooked some implicit assumptions.

> This is still uncertain, the patch is so large, I don't know who will
> review it, the person who has ability to review it must know Linux
> locking and OFED very well ? plus few of us are using OFED.

I do not think that people do need to know both at the same. I think  
the most critical part in the review is the linux compat shim. The  
pure OFED part is shared with Linux. Currently one needs to know both  
worlds (Linux + FreeBSD) to review it. If there is some good  
documentation, this can be split up into two parts. One part for  
people with good linux knowledge to check if the description in the  
docs is OK (semantic, invariants, assumptions, ...) and one part for  
people with good FreeBSD knowledge to check if the FreeBSD part is  
implementing what is described.

Bye,
Alexander.

-- 
One can't proceed from the informal to the formal by formal means.

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