[linux-yocto] utrace in recent linux-yocto kernels

Wade Farnsworth wade_farnsworth at mentor.com
Mon Sep 10 14:00:12 PDT 2012

Bruce Ashfield wrote:
> On 12-08-29 09:29 AM, Tom Zanussi wrote:
>> On Fri, 2012-08-03 at 13:37 -0400, Bruce Ashfield wrote:
>>> On 12-08-03 12:24 PM, Wade Farnsworth wrote:
>>>> Hi all,
>>>> While looking through the linux-yocto repositories, I notice that while
>>>> linux-yocto-3.0 has the utrace patchset merged, it appears that 3.2 and
>>>> 3.4 do not. utrace is necessary for proper systemtap userspace probe
>>>> support on these kernel versions, so it would be nice to have it
>>>> available.
>>>> Is there any intention to include this series in 3.2 and later kernels?
>>> There is! utrace is largely upstream in 3.5, and a backport is already
>>> done to 3.4, but pending some work to re-enable systemtap functionality
>>> on top of it.
>> Hi Bruce,
>> Any ETA on this? - I'd like to try it out. Let me know if you need any
>> help on anything here...
> I pushed the majority of it a while back, and systemtap works against it
> (the latest system tap that is).
> We could of course have missed something, but see these series:
> http://git.yoctoproject.org/cgit/cgit.cgi/yocto-kernel-cache/tree/features/uprobe
> and the in-tree version:
> http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-3.4/commit/?h=standard/base&id=544d531a337d560bd89f44ec45b0f6f2658c8e7c
> (and down, that's the top commit)

Hi Bruce,

Sorry for the delay in replying.  It appears that this patch only 
addresses the recently added inode-based uprobe solution, not the old 
utrace patchset that is present in linux-yocto-3.0.

Recent systemtap versions contain a utrace-based uprobes solution (built 
as an external kernel module) for ARM, but it hasn't been ported over to 
the newer inode-based uprobes solution that is implemented in the 
upstream kernel.  It would be nice to carry over the utrace patchset for 
the time being so that ARM users of newer kernels can use at least some 
sort of uprobes solution until the newer solution can be merged 
upstream.  Would it be possible to carry both the utrace and uprobes 
patches in the mean time?

Thanks for looking into this.


Wade Farnsworth

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