Bug 1256513 - Support libipt for Broadwell+ Intel(R) Processor Trace
Support libipt for Broadwell+ Intel(R) Processor Trace
Product: Red Hat Developer Toolset
Classification: Red Hat
Component: gdb (Show other bugs)
DTS 4.0 RHEL 7
x86_64 Linux
unspecified Severity unspecified
: alpha
: 6.0
Assigned To: Jan Kratochvil
Sergey Kolosov
Depends On: 1270539
  Show dependency treegraph
Reported: 2015-08-24 15:46 EDT by Jan Kratochvil
Modified: 2016-11-15 05:11 EST (History)
8 users (show)

See Also:
Fixed In Version: devtoolset-6-gdb-7.11.1-83.el7
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2016-11-15 05:11:46 EST
Type: Bug
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Jan Kratochvil 2015-08-24 15:46:28 EDT
Description of problem:
DTS/Fedora/RHEL GDB does not yet support new functionality of branch tracing available in Broadwell + Skylake CPUs:

 - record btrace pt

To get the feature one could either package new rpm libipt or bundle libipt with GDB (either dynamically or statically). libipt will be a new Fedora package in Fedora Rawhide but that does not seem to be quick enough for DTS-4.0.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
gdb -ex start -ex 'record btrace pt'

Actual results:
Target does not support branch tracing.

Expected results:
<nothing> ("info record" then should display PT is active)

Additional info:
Comment 2 Jan Kratochvil 2015-08-31 12:31:38 EDT
Fedora Rawhide libipt new package (.spec file) for review: Bug 1258572

So technically I can include it into DTS-4.0.
Comment 5 Jan Kratochvil 2015-09-04 14:14:08 EDT
gdb.rawhide+libipt.rawhide are built:
  https://koji.fedoraproject.org/koji/taskinfo?taskID=10944184 gdb.rawhide
  https://koji.fedoraproject.org/koji/buildinfo?buildID=682567 libipt.rawhide
Comment 7 Jan Kratochvil 2016-08-10 11:29:52 EDT
"intel_pt_interrupt" is still not found in:

But it is now present thanks to RHEL-7.3 kernel Bug 1270539 in:

It requires Intel Broadwell or higher where does exist:
and also there is in CPU flags:
  grep -w intel_pt /proc/cpuinfo

Successfully tested it in Beaker with kernel-hw loaned machine:
Comment 15 errata-xmlrpc 2016-11-15 05:11:46 EST
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.


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