Three major areas - Device Drivers, Virtualization, and Network Filtering It's not so much fat as it is feature support and what's enabled by default. Most peo

Three major areas - Device Drivers, Virtualization, and Network Filtering It's not so much fat as it is feature support and what's enabled by default. Most people want the "default" configuration to work out of the box on whatever computer they have. E.g. If you take a look at "x86_64_defconfig", nearly every Ethernet card that Linux supports is enabled. Odds are you only have one of those in your (desktop) system. However, unless you shopped around for specific NICs, odds are you don't own two systems that use the same ethernet driver. For those of us who want to only compile the support for exactly what we use, it is still possible to compile the kernel small enough to boot off of a 1.44 MiB floppy with a minimal initial ramdisk, assuming the system you want to use it on is old. Modern systems require so much more code to use the hardware in them, and as Linux has become the single most used operating system kernel on the planet, the amount of code for device drivers has grown astronomically. The kernel contains a minimal configuration called "tinyconfig" which turns off literally anything that be while retaining a functioning kernel. A tinyconfig kernel + TTY support compiles to about 500 KiB. Enabling all of the drivers to support hardware via the BIOS (AT style disk control, floppy, display out, etc.), and ELF support will yield a kernel of ~790 KiB, a little more than half of your 1.44 MiB floppy. Assuming you can fit useful userspace tools in the remaining space, you could still load from a floppy.