[bicolao]

> But you're right: ulimately the kernel is just a program.

Play a bit with user mode linux [1] the kernel becomes literally a linux program, that I believe you can even debug with gdb (hazy memory as I tried uml last time maybe a decade ago)

In theory you can also attach gdb to qemu running linux, but that's more complicated.

[1] https://en.wikipedia.org/wiki/User-mode_Linux

[ktpsns]

And User Mode Linux was the basic technology for dirt cheap (not so) virtual machines at some VPS providers 15yrs ago. This had some disadvantages, for instance you could not load custom kernel modules in the VM (such as for VPN), actually you could not modify the kernel at all.

[antonkochubey]

Another major disadvantage, at least back then, was that it did not support SMP at all