webbsmurfen123
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Joined: Mon Jun 17, 2019 8:41 pm

Persistent RAM in raspberry pi 2B

Mon Jun 17, 2019 8:50 pm

If i change the amount GPU ram inside the raspi-config, will it be persistent, so if i change to another SDHC memory with another OS it still will remember the settings or do i have to add this for every OS?

jamesh
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Re: Persistent RAM in raspberry pi 2B

Mon Jun 17, 2019 10:13 pm

The Pi has no persistent memory*, everything is stored on the SD card.


* It has something called OTP (one time programmable) memory which is persistent, but that is tiny (64 32bit words?) and not accessible to users.
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gkaiseril
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Re: Persistent RAM in raspberry pi 2B

Mon Jun 17, 2019 10:18 pm

You will need to change or add the gpu-mem option value in the config.txt file on the SD card.

Memory options in config.txt

The above link shows how to use the gpu_mem_xxxx options so the memory will be automatically set based on the gpu memory available for the various models of the Pi.
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Re: Persistent RAM in raspberry pi 2B

Tue Jun 18, 2019 12:11 am

webbsmurfen123 wrote:
Mon Jun 17, 2019 8:50 pm
If i change the amount GPU ram inside the raspi-config, will it be persistent, so if i change to another SDHC memory with another OS it still will remember the settings or do i have to add this for every OS?
You have to configure everything for every OS and boot device. Nothing is persistent, as far as the OS goes. There are a few OTP (One Time Programmable) bits that can be set for certain things, like enabling USB boot mode on the older 3B model or changing the boot delay to wait longer for slow boot devices, and those are permanent (persistent) changes. But there is no non-volatile memory, like your typical Windows PC BIOS (all of that is on the SD card).

It is possibly to save some configuration files and use them on another card. For example, I have a copy of wpa_supplicant.conf with my wireless networks information, and I can just copy that to a new card to automatically connect to my WiFi when it boots. But that just simplifies the manual setup and is not the same as persistent, non-volatile memory (although it is possible to add those configuration files to a custom burn-n-boot image to save even more time).
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