How to enable a ftrace function on L3.14.28 BSP for i.MX6DL

[yuuki]

Dear all,

We want to implement ftrace function in L3.14.28 Linux BSP.
(bb file is based on the fsl-image-gui.bb)
However I cannot enable the ftrace function.

Would you tell me how to enable the ftrace function?

We refer to the following URL.

 - https://wiki.yoctoproject.org/wiki/Tracing_and_Profiling#General_Setup
 - https://yoctoproject.org/docs/1.7/profile-manual/profile-manual.html

We added the following line to conf/local.conf.
  $ EXTRA_IMAGE_FEATURES = "debug-tweaks tools-profile"
  $ PACKAGE_DEBUG_SPLIT_STYLE = 'debug-file-directory'

And then bitbak is executed.
However, tracing folder is not made under /sys/kernel/debug/.

We suspect that a procedure is not enough.
If there is the package which should be added to IMAGE_INSTALL_append more, would you tell us it?

On the other hand, we exclude the following item from IMAGE_INSTALL_append
 - packagegroup-fsl-tools-testapps
 - packagegroup-fsl-tools-benchmark

May we have any advice?

Best Regards,
Yuuki

[eric_mascio]

I was able to get it to work by using menuconfig to enable ftrace. Just modifying the local.conf file did not work as specified in the yocto directions and I am not sure that step is necessary.

what I did to fix the problem

•  $> bitbake -c menuconfig linux-imx
  • modify .config to enable ftrace, 
  • From the menu choose  Kernel Hacking --> Tracers
  • Go into the Tracers sub-directory and enable [ ] Function Tracers ( this also enables Function Graph Tracers.

• Do not clean. That will remove .config
• Verify  if ftrace is enabled,
  • RESULT - CONFIG_FTRACE = y
  • $> less  tmp/work/imx8qxpzebra-poky-linux/linux-imx/4.14.78-r0/build/.config
  • Sample from .config
• CONFIG_HAVE_FUNCTION_TRACER=y
• CONFIG_HAVE_FUNCTION_GRAPH_TRACER=y
• CONFIG_FTRACE=y

• recompile the kernel, $> bitbake -c compile -f  linux-imx
• Rebuild images $> bitbake fsl-image-validation-imx
• When I reloaded the image,  fsl-image-validation-imx-imx8qxpmek.sdcard , on the target the tracing folder was there,  /sys/kernel/debug/tracing.

[eric_mascio]

I have the same problem. I made the changes as described in the wiki

 - https://wiki.yoctoproject.org/wiki/Tracing_and_Profiling#General_Setup 

I did  a clean and rebuild of the image.

$> bitbake -c clean fsl-image-validation-imx

$> bitbake  fsl-image-validation-imx

Then loaded the .sdcard image onto the target. There is no tracing directory as described in the wiki page at /sys/kernel/debug/.

On the target the debugfs, where the tracing sub-directories should be, is mounted,

> debugfs on /sys/kernel/debug type debugfs (rw,relatime).

is there a different image that should be built or a different way to build it?

[art]

First, try to build the image without doing any modifications in the IMAGE_INSTALL_append file.