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enter image description hereI am using raspberry pi 4b after successfully installation of raspbian os i connected the pi with raspberry display (official raspberry pi 7 inch display) then error msg appears as kernel panic cant allocate swiotlb buffer before and cant allocate dmabouncer buffer now Please help

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  • successfully installation of os which OS? where did you get it from? I wonder if you can take a picture of the whole screen rather than part of it - also what is this raspberry display you've connected to?
    – Jaromanda X
    Dec 29, 2020 at 9:52
  • I have installed raspbian os and display is official raspberry pi 7 inch display. Photo is of whole screen only one line is not visible.
    – vaibhav kadam
    Dec 29, 2020 at 11:27
  • Raspbian is outdated. You should use the up to date Raspberry Pi OS.
    – Ingo
    Dec 29, 2020 at 18:29
  • was hoping to see the last SUCCESSFUL boot operation just above what you've taken a picture of - maybe connect to a TV/Monitor - you may see more above the error to be able to pinpoint where in the boot process it has failed
    – Jaromanda X
    Dec 29, 2020 at 22:59
  • confirming one more thing - other than the 7 inch raspberry pi display, you have nothing else connected to the pi and have made absolutely no changes to the boot partition?
    – Jaromanda X
    Dec 29, 2020 at 23:01

1 Answer 1

Reset to default
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I ran into this same issue with a new install of Pi OS after setting the GPU memory to 896 MB in raspi-config.

To fix it without reinstalling:

  1. Put the SD card in another computer that can read the "boot" filesystem. I believe it is a FAT32 filesystem.

  2. Open "config.txt" and alter the "gpu_mem" setting. Set it to something like 512 or lower.

I don't know what the upper limit is, but 512 worked for me and is recommended as the maximum value for a Pi with 1GB memory or greater.

https://www.raspberrypi.org/documentation/configuration/config-txt/memory.md

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  • The upper limit is 512. Nobody should need that amount of GPU RAM, Start with 192 and work from there.
    – Dougie
    Jan 7, 2021 at 16:46
  • Just hit this... why is the upper limit in the UI widget 896?
    – Gabe
    Jan 10, 2021 at 21:17
  • Had the same issues. After reading a bit, this setting is really just for video decoding and the desktop -- 3d applications override this anyway, so no need to set it so high.
    – Felix Dombek
    Jan 11, 2021 at 23:17
  • You are amazing, thank you. I am another dumb-dumb who maxed my GPU to 896 even when the internet told me 512 was the max lol.
    – Ryan
    Oct 14, 2021 at 23:03

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