Re: Converting a device driver for real time kernel - OT

[Armin Steinhoff <as@steinhoff-automation.com>]

Hi all,

I know it's OT ... but what is the real name of

 - "real time kernel (2.6.22.19-0.14-rt)"
 - "!RT kernel" 
 - "-rt kernel"

Any ideas ?  Is it the RTP kernel --- P stands for pre-emption ?

--Armin





Thomas Gleixner wrote:
> On Tue, 9 Feb 2010, Leggo, Adam (UK) wrote:
>
>   
>> Hello,
>>  
>> What is the best way of converting an existing device driver to work
>> under a real-time kernel?
>>  
>> A device driver provided for a special serial card (Curtiss Wright SL240
>> sFDFP card http://www.cwcembedded.com/products/0/1/461.html) works under
>> vanilla Linux (SLES SP10 SP2 kernel 2.6.16.60-0.21-smp), but compiling
>> the driver under the real time kernel (2.6.22.19-0.14-rt) the system
>> locks up and crashes. The rt kernel is being used to write large amounts
>> of data from the serial card to disk and testing has found the rt kernel
>> has the best consistent write performance.
>>  
>> I have gone back to the supplier and they are not interested in
>> developing a real time version of the driver. So I am trying to modify
>> the driver myself. The driver code can be provided if anyone wants a
>> look (released under GPLv2).
>>  
>> Any assistance would be useful.
>>     
>
> The problem of the driver is probably broken locking, which needs to
> be fixed for !RT as well.
>
> But if you want to fix it your self and need some assistance it would
> be helpful if you could:
>
> 1) Run against a recent -rt kernel
>
> 2) provide a serial console log of the kernel crash
>
> 3) run the kernel with CONFIG_PROVE_LOCKING=y and provide the output
>
> 4) upload the source to some place so we can at least have a look at
>    the code to give you hints.
>
> Thanks,
>
> 	tglx
>
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