[lttng-dev] How to compile lttng-modules using full kernel source tree.

[Rui Han]

Thank you Mathieu.

Regards,
Rui

On Mon, Mar 23, 2015 at 10:09 AM, Mathieu Desnoyers <
mathieu.desnoyers at efficios.com> wrote:

> Please refer to:
>
> http://lttng.org/docs/#doc-building-from-source
> which points to:
> https://github.com/lttng/lttng-modules/blob/master/README.md
>
> Thanks,
>
> Mathieu
>
> ----- Original Message -----
>
> > Hi Mathieu,
> > Thank you very much for your reply.
> > Where in make file can I specify the full kernel source path? I found the
> > following makefile snippet but I cannot locate where the $(srctree)
> variable
> > is initialized. Could you please give me some insight or point to the
> > related material? Thank you very much.
> > ifneq ($(CONFIG_EXT4_FS),) ext4_dep = $(srctree) /fs/ext4/*.h ext4 =
> > lttng-probe-ext4.o
> > ifeq ($(wildcard $(ext4_dep)),) $(warning Files $(ext4_dep) not found.
> Probe
> > "ext4" is disabled. Use full kernel source tree to enable it.) ext4 =
> > endif
> > obj-m += $(ext4)
> > endif
>
> > Regards,
> > Rui
> > On Mon, Mar 23, 2015 at 9:42 AM, Mathieu Desnoyers <
> > mathieu.desnoyers at efficios.com > wrote:
>
> > > > Hey,
> > >
> >
> > > > See comments below.
> > >
> >
>
> > > > On 2015-03-20 09:34 AM, Rui Han wrote:
> > >
> >
>
> > > > > Hi,
> > > >
> > >
> >
> > > > > I have encountered following output when I try to run make from the
> > > > > lttng-modules source cloned from git repo. I have tried in a clean
> > > > > install
> > > > > of both 12.04 and 14.04.
> > > >
> > >
> >
> > > > > make -C /lib/modules/3.13.0-45-generic/build
> > > > > M=/home/troguard32/lttng/lttng-modules modules
> > > >
> > >
> >
> > > > > make[1]: Entering directory
> `/usr/src/linux-headers-3.13.0-45-generic'
> > > >
> > >
> >
> > > > > /home/troguard32/lttng/lttng-modules/probes/Makefile:30: File
> > > > > /usr/src/linux-headers-3.13.0-45-generic/virt/kvm/iodev.h not
> found.
> > > > > Probe
> > > > > "kvm" x86-specific is disabled. Use full kernel source tree to
> enable
> > > > > it.
> > > >
> > >
> >
> > > > > /home/troguard32/lttng/lttng-modules/probes/Makefile:142: Files
> > > > > /usr/src/linux-headers-3.13.0-45-generic/fs/btrfs/*.h not found.
> Probe
> > > > > "btrfs" is disabled. Use full kernel source tree to enable it.
> > > >
> > >
> >
> > > > > /home/troguard32/lttng/lttng-modules/probes/Makefile:158: Files
> > > > > /usr/src/linux-headers-3.13.0-45-generic/fs/ext4/*.h not found.
> Probe
> > > > > "ext4"
> > > > > is disabled. Use full kernel source tree to enable it.
> > > >
> > >
> >
> > > > > Building modules, stage 2.
> > > >
> > >
> >
> > > > > MODPOST 43 modules
> > > >
> > >
> >
> > > > > make[1]: Leaving directory
> `/usr/src/linux-headers-3.13.0-45-generic'
> > > >
> > >
> >
>
> > > > > when run make modules_install, it seem the installation is
> successful,
> > > > > but
> > > > > the output is abnormal, giving repeated “Can’t read private key”
> > > > > messages.
> > > >
> > >
> >
> > > > > If I ignore this message and install all other lttng components, it
> > > > > seems
> > > > > lttng kernel tracer is working fine.
> > > >
> > >
> >
> > > > > My question is,
> > > >
> > >
> >
>
> > > > > 1. How to completely remove this abnormal message? where to
> specify the
> > > > > full
> > > > > kernel source path in make file? (I am a makefile beginner)
> > > >
> > >
> >
>
> > > > Abnormal message being the key related one? We are looking into but
> this
> > > > does
> > > > not in any way change behavior.
> > >
> >
> > > It's because you are building against your distribution kernel, for
> which
> >
> > > only your distribution has the signing key. Therefore, the build
> complains
> >
> > > that the modules are not signed. But since your distro kernel allows
> >
> > > loading unsigned modules, it works fine, but outputs a warning.
> >
>
> > > > As for the warning for kvm/btrfs/ext4. Nothing to worry about you
> simply
> > > > don't have these components installed on your system.
> > >
> >
> > > A small correction: you may have kvm/btrfs/ext4 on your system.
> However,
> > > lttng-modules
> >
> > > is letting you know that it cannot build the probes to attach to those
> > > subsystem, because
> >
> > > you build against the installed kernel headers, rather than against the
> > > full
> > > kernel source tree.
> >
> > > This is because those subsystem place their instrumentation headers
> into
> > > subdirectories of
> >
> > > the Linux kernel tree that are not installed on the system.
> >
>
> > > Thanks,
> >
>
> > > Mathieu
> >
>
> > > > > 1. How to check whether the lttng-modules installed is fully
> functional
> > > > > or
> > > > > not?
> > > >
> > >
> >
>
> > > > A quick check is the one you probably did: lttng list -k. You can
> also
> > > > run
> > > > the root_regression tests from lttng-tools. Under ./tests you can run
> > > > ./run.sh root_regression while being root.
> > >
> >
>
> > > > > 1. Does the above message is just telling me that I will be able
> to use
> > > > > the
> > > > > full function of lttng-modules except those file system probe
> mentioned
> > > > > in
> > > > > the make output?
> > > >
> > >
> >
>
> > > > Exactly.
> > >
> >
>
> > > > > Thank you very much.
> > > >
> > >
> >
> > > > > Best regards,
> > > >
> > >
> >
> > > > > Rui
> > > >
> > >
> >
> > > > > ​
> > > >
> > >
> >
>
> > > > > _______________________________________________
> > > >
> > >
> >
> > > > > lttng-dev mailing list lttng-dev at lists.lttng.org
> > > > > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> > > >
> > >
> >
>
> > > > --
> > >
> >
> > > > Jonathan R. Julien
> > >
> >
> > > > Efficios
> > >
> >
>
> > > > _______________________________________________
> > >
> >
> > > > lttng-dev mailing list
> > >
> >
> > > > lttng-dev at lists.lttng.org
> > >
> >
> > > > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> > >
> >
>
> > > --
> >
> > > Mathieu Desnoyers
> >
> > > EfficiOS Inc.
> >
> > > http://www.efficios.com
> >
>
> > ​
>
> --
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
>
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