[Crash-utility] trace.so failing to load on newer kernels

[Lai Jiangshan]

On 10/14/2010 01:06 AM, Dave Anderson wrote:
> 
> ----- "Jeff Moyer" <jmoyer at redhat.com> wrote:
> 
>> Hi,
>>
>> I was trying to use the trace.so extension module, but it was bailing
>> out early with no explanation.  I tracked it down to the fact that the
>> system member of the trace_event_call structure no longer exists.  It
>> was moved up to the class structure.  The change was introduced in this
>> upstream commit:
>>
>> commit 8f0820183056ad26dabc0202115848a92f1143fc
>> Author: Steven Rostedt <srostedt at redhat.com>
>> Date:   Tue Apr 20 10:47:33 2010 -0400
>>
>>     tracing: Create class struct for events
>>
>> I don't have the cycles to fix this up right now, so I was hoping
>> someone else would.  ;-) Bonus points for printing useful error messages
>> when the module fails to load for some reason.
>>
>> Cheers,
>> Jeff
> 
> (I've added the author Lai Jiangshan to the cc: list to address this issue.)
> 
> Hello Lai,
> 
> Can I also make a couple suggestions/requests when you fix this issue?
> 
> (1) There should be a protection mechanism in place to prevent the use
>     of a bogus structure member offset in any virtual address calculation.
> (2) I've also run into the frustration of trying to figure out which
>     of the multiple failure reasons that can occur when the command
>     ftrace_init fails to load, so I agree with Jeff that it would be
>     very helpful to put some error messages in place.
> (3) When you make the fix for for the movement of the "system" member
>     from the ftrace_event_call to the ftrace_event_class structure,
>     please make it backwards-compatible so that the module still 
>     works for earlier kernels.
> 
> Thanks,
>   Dave
> 
> 

Hello, Dave

Our customer's and my vendor's requirement is very low: make it work at
the incoming RHEL6(2.6.32). so I don't get so much time to make it always
updated. I had written a patch which make it fit for the kernel newer than
2.6.32, but it still not fit the newest kernel, I will rewrite it,
(fit to the new kernel and compatible to the old kernels) and more checks.

Thank you for your suggestions, I will use them in the new patches.

Thanks,
Lai