I am a fan of live media. When I am not feeling adventurous I leverage an XFCE spin of Fedora. The release as of writing is Fedora 34 x86_64.
I depend on a Windows program in my mostly Linux-only lifestyle, and wine makes this possible. When dabbling with this dependency in conjunction with live media, I discovered I ran out of RAM-backed file system space.
I am not versed in how Fedora yields a RAM-backed file system overlay. From a cat /proc/filesystems, it does not appear to use overlayfs. overlayfs is not in the list. Does it manifest in the pivot through /run/initramfs? I am unsure, and will not explore or find the answer in this post.
What I need is a way to dnf -y install wine.
After two other rounds of trial and error, I got this foundation script. It does not check or handle errors, but in essence, automates the steps necessary to get wine installed so I can use my Windows program.
My laptop has 32GB of RAM, and in my experience, the modern live images demand a minimum of 4GB of RAM to do the very minimum and with web browsing out of the question.
The cheatiest angle - (a new word for me => cheatiest) - is to make more space on /usr since that is where most libraries and binaries will end up. I did not evaluate if any directory below /usr (e.g. /usr/share or /usr/lib) is a better candidate because, as said, cheatiest.
Now that you know I target /usr, the overall size of /usr hovers slightly above 4 GB uncompressed. It should be an appreciable amount less than 4 GB when subjected to the fast compression used by the zram module. The overall size of /usr (df -h) with wine installed, registers slightly above 6.3 GB. This means my cheatiest approach is expecting at least 8 GB of installed RAM. There is ample room for improvement, yet this solves my need for a live system where I can use my Windows program without concern of a computer's primary purpose.
EDIT: updated on 11/4/2021.
Here's the code.
sudo swapoff /dev/zram0
sudo rmmod zram
sudo modprobe zram num_devices=8
sudo find /sys/devices -name disksize -exec chmod 777 {} \;
find /sys/devices -name disksize | while read F; do echo $((16384*1048576)) > ${F}; done
sudo mkfs.ext4 /dev/zram0
sudo mkdir /tmp/0
sudo mount /dev/zram0 /tmp/0
cd /usr
sudo cp -av ./* /tmp/0
sudo setenforce permissive
host dns.google && ping -c 1 dns.google && echo "Looks good."
host dns.google || ping -c 1 dns.google || echo "No good. Restart this script." || exit 1
sudo dnf -y install wine
echo "That should have worked without running out of file system space."
echo "But for reasons (unknown to me) doing the same kind of effort by "
echo "first dd'ing the live image (using its dev loop to a zram dev)"
echo "and cp -av'ing the file system over to a larger ext4 formatted"
echo "ext4 fs, did not work when mounting to root. It shows the mount"
echo "as being updated, but df -h does not; rather it shows the previous"
echo "space from the live mount. Again, I do not understand how the live"
echo "mount provides the compressed fs image, and subsequently, gives a "
echo "RAM overlay."
cd ~
mkdir .wine
sudo mount tmpfs -t tmpfs $(pwd)/.wine -o exec,uid=1000
wine cmd
