Description of problem: GCC does a poor job at emitting location list information for parameters to inlined function instances. This, coupled with gcc's greater propensity to inline functions, is seriously limiting the visibility of those values to debuggers and to systemtap. Version-Release number of selected component (if applicable): 4.1 How reproducible: Common. Any kernel function that's static and has a single caller is now tending to be inlined. This renders its parameters invisible. There are many many cases. See also: http://gcc.gnu.org/PR23551 http://sources.redhat.com/PR1155
This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux maintenance release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Update release for currently deployed products. This request is not yet committed for inclusion in an Update release.
This request was previously evaluated by Red Hat Product Management for inclusion in the current Red Hat Enterprise Linux release, but Red Hat was unable to resolve it in time. This request will be reviewed for a future Red Hat Enterprise Linux release.
ASAP.
This should ahve been nominated for 5.2.z. I could swear I had done that already. This important since GSS/Eng. will rely upon STap for troubleshooting, etc.
I'm afraid any substantial improvement is only possible with Alex code, which isn't even in 4.4 yet, and is definitely not backportable to 4.1 nor 4.3.
Development Management has reviewed and declined this request. You may appeal this decision by reopening this request.
Release note added. If any revisions are required, please set the "requires_release_notes" flag to "?" and edit the "Release Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. New Contents: SystemTap currently uses GCC to probe user-space events. GCC is, however, unable to provide debuggers with precise location list information for parameters. In some cases, GCC also fails to provide visibility on some parameters. As a consequence, SystemTap scripts that probe user-space may return inaccurate readings.