CTurt writes about console hacking and emulation, including PS4, PS2, Game Boy, and Nintendo 64 exploits.
HN commenters recommend its PS4 hacking writeup for learning ROP, and link its Game Boy emulator and FreeDVDBoot posts.
PS3 did—I believe PS4 is not nearly as heavily modified[1]. It is certainly locked down though, at least after the early PS3s where you could, say, install Linux and build a HPC cluster[2].
1. Mostly from people who've hacked it; https://cturt.github.io/ps4.html seems to suggest it's a relatively stock FreeBSD kernel with some added system calls and a possibly heavily modified NetBSD userland.
2. http://phys.org/news/2010-12-air-playstation-3s-supercomputer.html
If this is true then it's a real bummer. Jailbreaking tends to pave the way for a lot of bad things. Rampant piracy and multiplayer cheating will totally bork the playstation ecosystem.
Edit:
I dug into this a little bit and it doesn't seem beyond the realm of possibility that this is credible. A little more info (though no smoking gun) can be found at the tweeters GitHub page http://cturt.github.io/articles.html
Jails are used on the Playstation 4 and with some 36 Million PS4s sold so far that's a huge use of jails in production. Here's a quote from an article talking about it,
"We can prove the existence of FreeBSD jails being actively used in the PS4's kernel through the auditon system call being impossible to execute within a jailed environment"
This quote is from: https://cturt.github.io/ps4.html
This shogi game for the N64 included network hardware in the cartridge (see photo below) for online play. Unfortunately it also allowed arbitrary remote code execution.
https://twitter.com/sdhizumi/status/1274594780899500032?s=21
Exploit homepage:
https://cturt.github.io/shogihax.html
(Dear mods, the link above and its title might be better for this submission.)
These two articles are probably relevant and come from the same person:
1. http://cturt.github.io/ps4.html
2. http://cturt.github.io/ps4-2.html
They cover pretty much every question about the WebKit exploit and this open-source SDK.
https://cturt.github.io/freedvdboot.html
I think this explains it.
I've been using free mcboot on a memory card with hard disc games for years. I never knew burnt dvds where possible without mod chip