Hello, I'm new also in this forum and found this subject very interesting. First of all, all the software actually run in RAM as they are loaded from the HDD. In fact you can see how the whole RAM memory is being filled in time... This might be a little bit strange to people to get things done only in RAM... maybe we can use a CD drive or even the HDD, but anyway... there are some people who like to try different things, maybe just for fun...
Running the whole system in ram, will actually run as fast as the RAM and processor can handle. And also in might have a very useful applications for mobility projects.
This subject is quite a challenge so far. Because I have tried to achieve run only the distro I like in ram.
My goal is to copy and run from an USB flash memory the whole live CD from the distro I usually use.
But well, the trick relays on the INITRD file. You can grab the INITRD image and mount it in order to modify it. The INITRD file is an image of a small Linux OS that always run in RAM in first place before switching the root directory to the HDD or the corresponding device where the Linux system was installed.
What I want to do is to create a TMPFS mount (RAM) while initrd is running and use dd to copy the image into that directory and then switchroot to the RAM. So far I have achieved to run INITRD and stay there only as a shell (some kind of embedded system). Obviously if I exit the shell, the system crash and gives me backtraces since it did not load the real root.
I do not know if someone have reached this step and I would like to discuss this. The goal is
1. Run a personalized initrd
2. mount a temp filesystem in RAM
3. use DD or other method to copy the image into ram
4. have the image available for switchroot
5. continue the boot process, which in theory it will be all in ram
I'm using a LIVECD image to try this since itīs INITRD image is designed to load the necessary devices in an environment of mobility... this INITRD file is the key. Still trying and proving.
Please, this subject is quite interesting, Keep posting!