Rebuild and Install Module i915 for GPU Analysis on CentOS*

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Intel® VTune™ Profiler User Guide

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ID 766319

Date 12/16/2022

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Rebuild and Install Module i915 for GPU Analysis on CentOS*

NOTE:

Profiling support for CentOS* 7 is deprecated and will be removed in a future release.

To collect i915 ftrace events required to analyze the GPU utilization, your Linux kernel should be properly configured. If the Intel® VTune™ Profiler cannot start an analysis and provides an error message: Collection of GPU usage events cannot be enabled. i915 ftrace events are not available. You need to rebuild and install the re-configured i915 module. For example, for kernel 4.14 and higher, these settings should be enabled: CONFIG_EXPERT=y and CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS=y.

If you update the kernel often, make sure to build the special kernel for GPU analysis.

NOTE:

Installing the kernel requires root permissions.

On CentOS* systems, if you update the kernel rarely, you can configure and rebuild only module i915 as follows:

Install build dependencies:

sudo yum install flex bison elfutils-libelf-devel

Create a folder for kernel source:
```
mkdir -p /tmp/kernel
cd !$
```
Get your kernel version:
```
uname -r
```
This is an example of the command output:
```
4.18.0-80.11.2.el8_0.x86_64
```

Get source code for the kernel:

wget http://vault.centos.org/8.0.1905/BaseOS/Source/SPackages/kernel-4.18.0-80.11.2.el8_0.src.rpm

rpm --define "_topdir /tmp/kernel/rpmbuild" -i kernel-4.18.0-80.11.2.el8_0.src.rpm

tar -xf ./rpmbuild/SOURCES/linux-4.18.0-80.11.2.el8_0.tar.xz

Change the current directory:
```
cd linux-*
```

Configure the kernel modules:

cp /usr/src/kernels/$(uname -r)/.config ./

cp /usr/src/kernels/$(uname -r)/Module.symvers ./

Update the version in Makefile in the current directory.

The version value must be the same as in the uname -r command output. For example, if uname -r prints 4.18.0-80.11.2.el8_0.x86_64, the values in the Makefile should be:

VERSION = 4

PATCHLEVEL = 18

SUBLEVEL = 0

EXTRAVERSION = -80.11.2.el8_0.x86_64

Update the file, if required, and save it.
Make sure the kernel version is set correctly in the Makefile:
```
make kernelversion
```
The command output for the example above is the following:
```
4.18.0-80.11.2.el8_0.x86_64
```
In the new .config file, make sure the following settings are enabled:

CONFIG_EXPERT=y

CONFIG_FTRACE=y

CONFIG_DEBUG_FS=y

CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS=y

Update the file, if required, and save it.
Create a full config file for the kernel:
```
make olddefconfig
```

Build module i915:

make -j$(getconf _NPROCESSORS_ONLN) modules_prepare

make -j$(getconf _NPROCESSORS_ONLN) M=./drivers/gpu/drm/i915 modules

If you get the following error:

LD [M] drivers/gpu/drm/i915/i915.o
ld: no input files

you need to replace the following lines in scripts/Makefile.build:

link_multi_deps = \
$(filter $(addprefix $(obj)/, \
$($(subst $(obj)/,,$(@:.o=-objs)) \
$($(subst $(obj)/,,$(@:.o=-y))) \
$($(subst $(obj)/,,$(@:.o=-m)))),$^)

with the line:

link_multi_deps = $(filter %.o,$^)

NOTE:

See the patch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=69ea912fda74a673d330d23595385e5b73e3a2b9 for more information.

Install the new module:

sudo make M=./drivers/gpu/drm/i915 modules_install

Make sure the folder with the new driver is present in /etc/depmod.d/* files, or just add it:
```
echo "search extradrivers" | sudo tee /etc/depmod.d/00-extra.conf
```
Update initramfs:
```
sudo depmod 
sudo dracut --force
```
Reboot the machine:
```
sudo reboot
```

Make sure the new driver is loaded:

modinfo i915 | grep filename

The command output should be the following:

filename: /lib/modules/4.18.0-80.11.2.el8_0.x86_64/extradrivers/gpu/drm/i915/i915.ko

To roll back the changes and load the original module i915:

Remove the folder with the new driver from /etc/depmod.d/* files:
```
sudo rm /etc/depmod.d/00-extra.conf
```
Update initramfs:
```
sudo depmod
sudo update-initramfs -u
```
Reboot the machine:
```
sudo reboot
```

Parent topic: Set Up System for GPU Analysis

Related information

GPU Application Analysis on Intel® HD Graphics and Intel® Iris® Graphics

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Rebuild and Install Module i915 for GPU Analysis on CentOS*