Hi François,
On 7/16/24 3:01 PM, François Belias wrote:
Hello Kienan,
I've continued investigating my issue and discovered something new that
might shed some light. Here's the rundown:
1. To ensure my add-ons weren't causing problems, deleted all old
modules and I followed the documentation on the LTTng website
(https://lttng.org/docs/v2.13/#doc-building-from-source
<https://lttng.org/docs/v2.13/#doc-building-from-source>) and downloaded
`lttng-modules-2.13.13`.
2. Inside the downloaded folder, I successfully executed `make
KERNELDIR=/usr/src/linux-source-6.5.0` without any issues.
3. Subsequently, I ran `make KERNELDIR=/usr/src/linux-source-6.5.0
modules_install`, which also completed successfully.
4. After that, I updated the module dependencies using `sudo depmod -a`,
which went fine.
However, when I tried to load a module, such as `sudo modprobe
lttng-probe-kvm`, it reported that the module couldn't be found at
`/lib/modules/6.5.0-41-generic/`. Upon checking the logs, I confirmed
that step 3 had installed the modules in `/lib/modules/6.5.0/`.
To address this, I modified step 3 to simply `make modules_install`,
which then installed the modules correctly at
`/lib/modules/6.5.0-41-generic/` and ran again step 4. But now, when
attempting to load a module, I'm encountering the error `modprobe:
ERROR: could not insert 'lttng_probe_kvm': Exec format error`.
Do you have any insights or ideas on what might be causing this issue?
It sounds like /usr/src/linux-source-6.5.0 is not correct source for the
kernel that you are currently running.
When running `make modules_install` in your modified step 3 (without
KERNELDIR set), the modules were installed for your current kernel
directory as auto-detected by the build script.
What happens if you do the following
```
unset KERNELDIR
# Warning: this removes all untracked content from the lttng-modules
directory
cd /path/to/lttng-modules-source
git clean -dxf
make
sudo make modules_install
sudo depmod -a
```
KERNELDIR is set based on the current running kernel: `uname -r`. C.f.
https://github.com/lttng/lttng-modules/blob/434e86eea846b33cad57f1d8105089905f541853/Makefile#L16C1-L16C50
A couple of questions for you:
- Where did /usr/src/linux-source-6.5.0 come from?
- Which linux distribution + version are you using?
- Assuming your distribution has kernel packages, which do you have
installed, and do you have the corresponding kernel headers package
installed?
thanks,
kienan
Thanks again for your assistance.
Le mar. 16 juill. 2024, à 09 h 05, Kienan Stewart <kstew...@efficios.com
<mailto:kstew...@efficios.com>> a écrit :
Hi François,
On 7/15/24 6:10 PM, François Belias via lttng-dev wrote:
> Hello,
>
> I'm currently running Linux kernel version 6.5.0-41-generic and
> attempting to install LTTng from source. Here are the steps I
followed:
>
> - I cloned the LTTng git repository to my computer from
>
[https://github.com/lttng/lttng-modules.git](https://github.com/lttng/lttng-modules.git)
<https://github.com/lttng/lttng-modules.git%5D(https://github.com/lttng/lttng-modules.git)>
<https://github.com/lttng/lttng-modules.git](https://github.com/lttng/lttng-modules.git)
<https://github.com/lttng/lttng-modules.git%5D(https://github.com/lttng/lttng-modules.git)>>.
> - Downloaded the kernel source tree corresponding to my kernel
version
> to enable compilation.
> - Executed `make KERNELDIR=/path/to/my/linux/source`, which was
> completed successfully.
> - Ran `make KERNELDIR=/path/to/my/linux/source modules_install`,
also
> without any issues.
> - Finally, I executed `sudo depmod -a`, which was completed
successfully.
>
> However, when I attempt to load a module with commands like `sudo
> modprobe lttng-ketprobes` or "sudo modprobe lttng-tracer", I
encounter
> the following errors:
>
> - For `lttng-ketprobes`: `modprobe: FATAL: Module lttng-ketprobes
not
> found in directory /lib/modules/6.5.0-41-generic`.
> - For `lttng-tracer`: `modprobe: ERROR: could not insert
'lttng_tracer':
> Exec format error`.
If you rebuilt modules on the master branch as of yesterday you may
need
to clean the LTTng modules install directory, rebuild, and reinstall.
This is due to kprobes, kretprobes, and uprobes modules being included
in the tracer core module. C.f.
https://github.com/lttng/lttng-modules/commit/0c2c6606eb66cb5222ab7a2a4f8329fd5dfdef70
<https://github.com/lttng/lttng-modules/commit/0c2c6606eb66cb5222ab7a2a4f8329fd5dfdef70>
You may want to stick with running lttng-modules 2.13.x which will not
have breaking changes merged in.
The exec format error also could be due to modules that are installed
but built against a different version of the Linux kernel.
A few things to check
- If your kernel has been upgraded recently, ensure the new kernel is
the one actually running
- If the modules haven't been rebuilt since the upgrade, they should be
rebuilt and reinstalled
- As I recall, you are playing around with some addon modules - do any
of those modules define dependencies on the kprobes, kretprobes, or
uprobes modules which now are no longer produced by builds of the
master
branch
Is there further information in dmesg or journalctl regarding the
module
loading?
hope this helps.
thanks,
kienan
>
> I've confirmed that the modules exist but can't load them. I'm
unsure
> how to resolve these issues. Could someone please assist me?
>
> Thank you.
>
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