How to create your correct linux live cd?

Question

linux

All the best! Please do not scold too much :)
I decided to make the download of computers by pxe. I configured mikrotik as a server.
I found a small pxelinux.cfg default config on the Internet , several files were attached to it:

filesystem.squashfs
initrd
vmlinuz

I haven’t quite figured out what each of them is responsible for yet (bad with English :( )
everything seems to work, but I don’t know the login / password there, and I want to add something of my own to this collection.
Here’s how to write my own ala correctly custom live cd (so it can boot over network pxe boot)

Answer 1

filesystem.squashfs - compressed root filesystem (squashfs).
initrd - boot file system, in what form it is presented, it is not clear, you need to look at the boot logs.
vmlinuz - Linux kernel
Loading is as follows,
1) PXE loads vmlinuz and initrd over the network and transfers control to vmlinuz
2) vmlinuz - deploys initrd in memory and starts the init process
3) scripts in initrd load drivers, load filesystem.squashfs over the network into ramdisk and remount root to it
In other words, you need to deploy filesystem.squashfs, add everything you need, re-create filesystem.squashfs .
tldp.org/HOWTO/SquashFS-HOWTO/creatingandusing.html - that's about the same scenario.