mesa-progs

Learn how to use mesa-progs on Gentoo Linux to verify OpenGL rendering, confirm Intel Iris GPU acceleration, detect llvmpipe CPU fallback, and validate Mesa driver configuration

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Basic Usage

Install mesa and mesa-progs

echo ">=x11-libs/libdrm-2.4.131 video_cards_intel" >> /etc/portage/package.use/libdrm
emerge -1av x11-libs/libdrm media-libs/mesa x11-apps/mesa-progs x11-base/xorg-server

Print values in VIDEO_CARDS from /etc/portage/make.conf

portageq envvar VIDEO_CARDS

Check permissions

$ getfacl /dev/dri/card0 
getfacl: Removing leading '/' from absolute path names
# file: dev/dri/card0
# owner: root
# group: video
user::rw-
user:wuseman:rw-
group::rw-
mask::rw-
other::---

A broader solution is to add the user(s) needing access the video card to the video group

gpasswd -a $(whoami) video

Print default info

glxinfo 

Force an indirect rendering context

glxinfo -i

Brief output, print only the basics

glxinfo  -B

Print visuals info in verbose form

glxinfo -v

Print verbose visual information table

glxinfo  -t

Find the best visual and print its number

glxinfo -b

Print interesting OpenGL limits

glxinfo -l

Print a single extension per line

glxinfo -s

Advanced Usage

Show active OpenGL vendor and renderer (intel is what we want for HP EliteDesk 800 G3 DM 65W)

$ glxinfo -B | grep -E "OpenGL renderer|OpenGL vendor"
OpenGL vendor string: Intel
OpenGL renderer string: Mesa Intel(R) HD Graphics 530 (SKL GT2)

Verify which OpenGL driver is actually in use

glxinfo -B | grep -E 'OpenGL vendor|OpenGL renderer|OpenGL version'

Here is an example correct loading Intel driver

glxinfo -B 
name of display: :0
display: :0  screen: 0
direct rendering: Yes
Extended renderer info (GLX_MESA_query_renderer):
    Vendor: Intel (0x8086)
    Device: Mesa Intel(R) HD Graphics 530 (SKL GT2) (0x1912)
    Version: 25.3.3
    Accelerated: yes
    Video memory: 23443MB
    Unified memory: yes
    Preferred profile: core (0x1)
    Max core profile version: 4.6
    Max compat profile version: 4.6
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.2
OpenGL vendor string: Intel
OpenGL renderer string: Mesa Intel(R) HD Graphics 530 (SKL GT2)
OpenGL core profile version string: 4.6 (Core Profile) Mesa 25.3.3
OpenGL core profile shading language version string: 4.60
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile

OpenGL version string: 4.6 (Compatibility Profile) Mesa 25.3.3
OpenGL shading language version string: 4.60
OpenGL context flags: (none)
OpenGL profile mask: compatibility profile

OpenGL ES profile version string: OpenGL ES 3.2 Mesa 25.3.3
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20

When open vendor is set to Mesa we are failing, in this example we are failing to load intel and iris drivers

glxinfo -B 
name of display: :0
display: :0  screen: 0
direct rendering: Yes
Extended renderer info (GLX_MESA_query_renderer):
    Vendor: Mesa (0xffffffff)
    Device: llvmpipe (LLVM 21.1.8, 256 bits) (0xffffffff)
    Version: 25.3.3
    Accelerated: no
    Video memory: 23443MB
    Unified memory: yes
    Preferred profile: core (0x1)
    Max core profile version: 4.5
    Max compat profile version: 4.5
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.2
Memory info (GL_ATI_meminfo):
    VBO free memory - total: 31 MB, largest block: 31 MB
    VBO free aux. memory - total: 11743 MB, largest block: 11743 MB
    Texture free memory - total: 31 MB, largest block: 31 MB
    Texture free aux. memory - total: 11743 MB, largest block: 11743 MB
    Renderbuffer free memory - total: 31 MB, largest block: 31 MB
    Renderbuffer free aux. memory - total: 11743 MB, largest block: 11743 MB
Memory info (GL_NVX_gpu_memory_info):
    Dedicated video memory: 4293913726 MB
    Total available memory: 4293937170 MB
    Currently available dedicated video memory: 31 MB
OpenGL vendor string: Mesa
OpenGL renderer string: llvmpipe (LLVM 21.1.8, 256 bits)
OpenGL core profile version string: 4.5 (Core Profile) Mesa 25.3.3
OpenGL core profile shading language version string: 4.50
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile

OpenGL version string: 4.5 (Compatibility Profile) Mesa 25.3.3
OpenGL shading language version string: 4.50
OpenGL context flags: (none)
OpenGL profile mask: compatibility profile

OpenGL ES profile version string: OpenGL ES 3.2 Mesa 25.3.3
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20

Test Intel Iris Mesa driver explicitly

MESA_LOADER_DRIVER_OVERRIDE=iris glxinfo -B | grep -i "OpenGL renderer"

Configure Gentoo Linux to use Intel Iris only (Skylake cpu or newer is required)

VIDEO_CARDS="iris"

Verify that our cpu really is a skylake cpu

find /sys -name pmu_name -exec cat {} + 2>/dev/null

Check so hardware acceralator is available

if glxinfo -B 2>/dev/null | grep -qi llvmpipe; then
    echo "CPU rendering (bad)"
else
    echo "HW acceleration OK"
fi

Force Intel Iris driver for full OpenGL output

MESA_LOADER_DRIVER_OVERRIDE=iris glxinfo -B

Testing i965 video drier

MESA_LOADER_DRIVER_OVERRIDE=i965 glxinfo -B | grep -i "OpenGL renderer"

Verifying installed Mesa DRI drivers

ls -1 /usr/lib64/dri | grep -E '^(iris|crocus|i965)_dri\.so$'

Checking merge time and eta

Best POSIX, clean, robust solution (recommended)

genlop -c 2>&1 | tr '\r' '\n' | grep -e 'current merge time' -e 'ETA'

POSIX + extensible (best if you may format later)

genlop -c 2>&1 | tr '\r' '\n' | awk '/current merge time/ || /ETA/'

Minimal and sufficient (when output already has newlines)

genlop -c | grep -e 'current merge time' -e '^ *ETA'

Equivalent methods to extract merge time and ETA from genlop output

genlop -c 2>&1 | grep -e 'current merge time' -e 'ETA'
       current merge time: 1 minute and 39 seconds.
       ETA: 16 minutes and 5 seconds.
genlop -c 2>&1 | tr '\r' '\n' | grep -e 'current merge time' -e 'ETA'
       current merge time: 1 minute and 44 seconds.
       ETA: 16 minutes.
genlop -c 2>&1 | tr '\r' '\n' | awk '/current merge time/ || /ETA/'
       current merge time: 1 minute and 50 seconds.
       ETA: 15 minutes and 54 seconds.
genlop -c | tr '\r' '\n' | grep -E 'current merge time|ETA'
       current merge time: 2 minutes.
       ETA: 15 minutes and 44 seconds.
genlop -c | grep -e 'current merge time' -e '^ *ETA'
       current merge time: 2 minutes and 5 seconds.
       ETA: 15 minutes and 39 seconds.
genlop -c | grep -E --line-buffered 'current merge time|ETA'
       current merge time: 2 minutes and 10 seconds.
       ETA: 15 minutes and 34 seconds.
genlop -c | sed 's/\r/\n/g' | grep -E 'current merge time|ETA'
       current merge time: 2 minutes and 16 seconds.
       ETA: 15 minutes and 28 seconds.
genlop -c | tr '\r' '\n' | grep -E 'current merge time|ETA'
       current merge time: 2 minutes and 21 seconds.
       ETA: 15 minutes and 23 seconds.
genlop -c | grep -e 'current merge time' -e '^ *ETA'
       current merge time: 2 minutes and 32 seconds.
       ETA: 15 minutes and 12 seconds.

Tips and Tricks

Add genlop-status as an alias and we can simple check compile status

alias genlop-status='genlop -c 2>&1 | tr "\r" "\n" | grep -e "current merge time" -e "ETA"'

Resource(s)

• https://wiki.gentoo.org/wiki/Xorg
• https://wiki.gentoo.org/wiki/Xorg/Guide
• https://wiki.gentoo.org/wiki/Xorg/Hardware_3D_acceleration_guide
• https://app.readthedocs.org/projects/mesa/downloads/pdf/latest/