Booting to RAM

[rabcor]

I was wondering about ways to make gentoo boot from RAM.

There is one cross-distro method here which simply loads the root partition to RAM as it is.

But I think this method is a lot more elegant as it zips up (with GZIP, I would prefer LZMA) the root partition and then booots off of the zip as if it were an initramfs or so I think. I really like this method because I think if I use this, I can update my system while it is loaded to RAM by simply upadting it as I normally would, and then zipping it up again from there before I reboot. However this method is not cross distro, would it work with Gentoo? If not is there a Gentoo alternative or can I somehow just make it work with Gentoo?

PS: I would also like to load certain files to other hard drive partitions, like for example /usr/portage can get pretty huge so I can save a lot of space by storing it on a HDD/SSD partition, can I do this somehow with fstab or should I just use symlinks to do something like this?
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This picture was my biggest reason for ever trying Gentoo <3

[chithanh]

One option is to stay in initramfs even after boot. You never need to leave your initramfs, and it can be compressed to reduce on-disk size. A downside is that the decompressed initramfs needs to fit into LOWMEM (which is 896 MB by default on 32-bit systems).

Another option is to create a ramdisk which has the size of your root filesystem during early boot, then copy everything there and continue to boot from the ramdisk. You can use zram on memory-constrained systems to preserve memory.

There are some older threads here and here which might give you some pointers to get started.