Re: Systemtap on ARM arch results summary

[William Cohen <wcohen at redhat dot com>]

On 06/13/2014 02:13 PM, David Long wrote:
> On 06/12/14 11:42, William Cohen wrote:
>> On 06/12/2014 11:18 AM, David Long wrote:
> 
>> Hi David,
>>
>> Fedora on ARM sets the gcc compiler to "-march=armv7-a", so it is not generating thumb/thumb2 instructions.  I guess that makes it easier for Fedora.
>>
> 
> William,
> 
> I assume then that the C runtime library is also built without thumb instructions?  I think a thumb C library is causing a lot of my troubles, especially when tests do a process probe of ("*").

On Fedora nothing is built with thumb/thumb2 code. It seems like systemtap should be checking to see if the executable is thumb/thumb2 code and not try to instrument it if that is the case.
> 
> I assume you're testing with uprobes, now that the feature is available in the ARM kernel?  If so note there's a patch to cache flushing inside uprobes from Victor Kaminsky that went into the v3.16 merge window, and which is important (it fixes that intermittent at_var segv you first reported 8 months ago).

Yes, the kernel on that arm machine is being built with uprobe support.  The tests were with the 3.15 kernel and didn't have the 3.16 patch you mention.  I will be build a new kernel with that patch.
> 
> I'm curious to see the (compressed) systemtap.log from one of your more recent runs.  It would help me determine which failures might be real uprobes issues.

Attached is the systemtap.sum.gz from last thursday.

-Will

Attachment: systemtap.log.gz
Description: Unix tar archive