I have looked everywhere (both on and off StackExchange) for this but cannot get an answer:

I have a Raspberry Pi Zero W, which has 512MB of RAM total. I am running it headless, so I want to maximize available RAM. I have set gpu_mem=16 in the \boot\config.txt file and have rebooted the device.

When I run free -h I get the following output:

total used free shared buff/cache available Mem: 370M 20M 299M 2.6M 50M 300M

When I run vcgencmd get_mem arm && vcgencmd get_mem gpu I get:

arm=384M gpu=128M

This seems to be telling me that the GPU memory is still set to 128MB.

How can I properly free up this memory for general use by my applications?

Thanks ahead of time for any help you can give here.

  • 1
    Have you installed the official Raspbian image or the NOOBS image on your miniSD card? Are there any hdmi_ configuration options in your /boot/config.txt ? I believe the default gpu_mem is 64M not 128M. – RubberStamp Nov 22 '17 at 4:50
  • That's strange, considering it works perfectly as expected on my Pi Zero W, even if I go all out with the hdmi_* options. To ensure that it isn't an issue of formatting or a CRLF in your /boot/config.txt, does the problem persist if you enact the change via sudo raspi-config? – jdonald Nov 22 '17 at 4:55
  • RubberStamp - I am on Raspbian 'Stretch' as of the time of this writing with all of the firmware up-to-date. All hdmi_ entries in /boot/config.txt are commented out (this is a completely headless install). The gpu_mem setting is 16 (the minimum). – MrChips Nov 22 '17 at 6:53
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    jdonald - I tried updating the GPU split via raspi-config just to be sure, and everything is still coming up the same, so it's not a formatting issue. – MrChips Nov 22 '17 at 6:58
  • is the value the same in raspi-config and in config.txt file ? – Guy . D Nov 22 '17 at 9:14

Thanks to the forums over on raspberrypi.org I was able to find out the answer to this, so I am sharing it here for future reference...

ANSWER: The 128M of GPU RAM is still being reserved because I have the Raspberry Pi Camera enabled. The camera requires a minimum of 128M of GPU RAM to be held aside in order to function properly. This overrides the gpu_mem=16 setting in the \boot\config.txt file.

Going Deeper:

If you see this happening on your Pi, you can validate if it's the camera by going into the \boot\config.txt file and looking for the setting start_x=1. If that setting exists, your camera is enabled (even if you don't have one connected!). To turn it off, either set it to start_x=0 or comment it out, then reboot. You should see your GPU RAM allocation go back to whatever value you placed in the gpu_mem setting. Of course, then you won't have camera access, but hey, that's the deal, right?

Good luck, and thank you all for your help!

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