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Apple’s Darwin OS and XNU Kernel Deep Dive

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Re: Apple’s Darwin OS and XNU Kernel Deep Dive

#141

Post by _rpf »

wpm wrote: post #126
lunarlull wrote: post #45

Earlier quoted context omitted.

Why wouldn't Apple have been interested in a Linux option? They bought NeXTSTEP because of Jobs. Linux was already useable as a desktop OS in 2000, and they could have added in the UX stuff and drivers for their particular macs on top of it. There wouldn't have been any downsides for them, and it would have strengthened something that was hurting their biggest rival.

Jobs initially did not want to come back to Apple. Apple bought NeXTSTEP because between it and BeOS, Jean-Louis Gassee overplayed his hand and was asking way too much money for the acquisition. Apple then defaulted to NeXT. Jobs thought Apple was hopeless just like everyone else did at the time and didn't want to take over a doomed company to steer it into the abyss, and it's not like NeXT was doing great at the tim…

> Jean-Louis Gassee overplayed his hand

Well, there’s a parallel universe! Beige boxes running BeOS late-90s-cool maybe, but would we still have had the same upending results for mobile phones, industrial design, world integration, streaming media services…

Re: Apple’s Darwin OS and XNU Kernel Deep Dive

#142

Post by tedunangst »

adrian_b wrote: post #99
inkyoto wrote: post #80

Earlier quoted context omitted.

> As things now stand, FreeBSD represents many of the benefits of Darwin and the open source nature of Linux. No. FreeBSD has committed the original sin of UNIX by deliberately dropping support for all non-Intel architectures, intending to focus on optimising FreeBSD for the Intel ISA and platforms. UNIX portability and support for a diverse range of CPU's and hardware platforms are ingrained in the DNA of UNIX, howe…

Having used continuously both FreeBSD and Linux, wherever they are best suited, since around 1995 until today, I disagree. In my opinion the single factor that has contributed the most to a greater success for Linux than for FreeBSD has been the transition to multithreaded and multicore CPUs even in the cheapest computers, which has started in 2003 with the SMT Intel Pentium 4, followed in 2005 by the dual-core AMD C…

Not quite accurate history of SMP. FreeBSD had SMP well before 5.0, but not "fine grained" which is what the 5.0 release was all about. But the conversion led to many regressions.

Re: Apple’s Darwin OS and XNU Kernel Deep Dive

#143

Post by throw0101d »

inkyoto wrote: post #113
usrnm wrote: post #111

Earlier quoted context omitted.

Docker was created in 2013, long after BSDs had lost all their popularity. And, fwiw, FreeBSD pioneered containers long before Linux: https://en.m.wikipedia.org/wiki/FreeBSD_jail

FreeBSD jails are advanced chroot++. Albeit they do set a precedent for a predessor of true containers, they have: 1. Minimal kernel isolation. 2. Optional network stack isolation via VNET (but not used by default). 3. Rudimentary resource controls with no default enforcement (important!). 4. Simple capability security model. Most importantly, since FreeBSD was a very popular choice for hosting providers at the time,…

> 3. Rudimentary resource controls with no default enforcement (important!).

Seems pretty extensive to me, including R/W bytes/s and R/W ops/s:

* https://docs.freebsd.org/en/books/handbook/jails/#jail-resou...

* https://klarasystems.com/articles/controlling-resource-limit...

* https://man.freebsd.org/cgi/man.cgi?query=rctl

Re: Apple’s Darwin OS and XNU Kernel Deep Dive

#144

Post by kfir »

DeathArrow wrote: post #122
lunarlull wrote: post #45

Earlier quoted context omitted.

Why wouldn't Apple have been interested in a Linux option? They bought NeXTSTEP because of Jobs. Linux was already useable as a desktop OS in 2000, and they could have added in the UX stuff and drivers for their particular macs on top of it. There wouldn't have been any downsides for them, and it would have strengthened something that was hurting their biggest rival.

>it would have strengthened something that was hurting their biggest rival. If by biggest rival you mean Microsoft, it was Microsoft who saved Apple from bancrupcy in 1997.

Microsoft did that not out of charity to Apple but as an attempt to fend off the DOJ trial accusing it of being a monopoly

Re: Apple’s Darwin OS and XNU Kernel Deep Dive

#145

Post by LargoLasskhyfv »

tzs wrote: post #119
adrian_b wrote: post #99

Earlier quoted context omitted.

Having used continuously both FreeBSD and Linux, wherever they are best suited, since around 1995 until today, I disagree. In my opinion the single factor that has contributed the most to a greater success for Linux than for FreeBSD has been the transition to multithreaded and multicore CPUs even in the cheapest computers, which has started in 2003 with the SMT Intel Pentium 4, followed in 2005 by the dual-core AMD C…

I don't know if this had much affect on anything, but another thing that hindered using FreeBSD for some users was that Linux worked better as a dual boot system with DOS/Windows on a typical home PC. There were two problems. The first was that FreeBSD really wanted to own the whole disk. If you wanted to dual boot with DOS/Windows you were supposed to put FreeBSD on a separate disk. Linux was OK with just having a p…

Related fun fact up to maybe a decade ago: If you had a disk labeled/partitioned in FBSDs 'dangerously dedicated' style, and tried to image that, or reading the image of that with some forensic tool called Encase (running under Windows of course, how else could it be?), this tool would crash that Windows with an irrecoverable blew screen :)

I loved that!

Re: Apple’s Darwin OS and XNU Kernel Deep Dive

#146

Post by conradev »

llincerd wrote: post #130

Darwin is interesting because of the pace of radical changes to its core components. From dropping syscall backwards compatibility to mandatory code signing to dyld_shared_cache eliminating individual system library files to speed up dynamic executable loading. It's a very results-oriented design approach with no nostalgia and no sacred cows. I think only a big hardware vendor like Apple could pull it off.

Totally. The march continues with userspace drivers and exclaves[1]. I think it's fair to say that security is a big driver for their kernel evolution.

[1] https://www.theregister.com/2025/03/08/kernel_sanders_apple_...

Re: Apple’s Darwin OS and XNU Kernel Deep Dive

#147

Post by mycall »

swatson741 wrote: post #8

Whenever I see the Darwin kernel brought into the discussion I can't help but wonder how different things could have been if Apple had just forked Linux and ran their OS services on top of that. Especially when I think about how committed they are to Darwin it really paints a poor image in my mind. The loss that open source suffers from that, and the time and money Apple has to dedicate to this with a disproportionat…

One must consider the loss of control moving to Linux would bring. Even Google is reconsidering with fuchsia inline to replace Linux on Android.

Re: Apple’s Darwin OS and XNU Kernel Deep Dive

#148

Post by vermaden »

inkyoto wrote: post #113
usrnm wrote: post #111

Earlier quoted context omitted.

Docker was created in 2013, long after BSDs had lost all their popularity. And, fwiw, FreeBSD pioneered containers long before Linux: https://en.m.wikipedia.org/wiki/FreeBSD_jail

FreeBSD jails are advanced chroot++. Albeit they do set a precedent for a predessor of true containers, they have: 1. Minimal kernel isolation. 2. Optional network stack isolation via VNET (but not used by default). 3. Rudimentary resource controls with no default enforcement (important!). 4. Simple capability security model. Most importantly, since FreeBSD was a very popular choice for hosting providers at the time,…

I believe you have wrong view of how secure FreeBSD Jails are - definitely a lot more secure the rootless Podman for a start.

Isolation: With rootless Podman it seems to be on the same level as Jails - but only if You run Podman with SELinux or AppArmor enabled. Without SELinux/AppArmor the Jails offer better isolation. When you run Podman with SELinux/AppArmor and then you add MAC Framework (like mac_sebsd/mac_jail/mac_bsdextended/mac_portacl) the Jails are more isolated again.

Kernel Syscalls Surface: Even rootless Podman has 'full' syscall access unless blocked by seccomp (SELinux). Jails have restricted use of syscalls without any additional tools - and that can be also narrowed with MAC Framework on FreeBSD.

Firewall: You can not run firewall inside rootless Podman container. You can run entire network stack and any firewall like PF or IPFW independently from the host inside VNET Jail - which means more security.

TL;DR: FreeBSD Jails are generally more secure out-of-the-box compared to Podman containers and even more secure if you take the time to add additional layers of security.

> How battle-tested are FreeBSD Jails?

Jails are in production since 1999/2000 when they were introduced - so 25 years strong - very well battle tested.

Docker is with us since 2014 so that means about 10 years less - but we must compare to Podman ...

Rootless support for Podman first appeared late 2019 (1.6) so only less then 6 years to test.

That means Jails are the most battle tested of all of them.

Hope that helps.

Regards,

vermaden

Re: Apple’s Darwin OS and XNU Kernel Deep Dive

#149

Post by icedchai »

lunarlull wrote: post #45
andrewf wrote: post #40

Earlier quoted context omitted.

This presumes that Apple brought in Jobs as a decision maker, and NeXTSTEP was attached baggage. At the time, the reverse was true - Apple purchased NeXTSTEP as their future OS, and Jobs came along for the ride. Given the disaster that was Apple's OS initiatives in the 90s, I doubt the Apple board would have bought into a Linux adventure.

Why wouldn't Apple have been interested in a Linux option? They bought NeXTSTEP because of Jobs. Linux was already useable as a desktop OS in 2000, and they could have added in the UX stuff and drivers for their particular macs on top of it. There wouldn't have been any downsides for them, and it would have strengthened something that was hurting their biggest rival.

In the early 2000's, Linux was practically unusable as a desktop OS because the only "fully functional" web browser was Internet Explorer. Netscape 4.x "worked" but was incredibly unstable and crashed roughly every half hour. Mozilla / Phoenix / Firefox wasn't done yet. Chrome didn't exist.

It was a very different world. We won't even talk about audio and video playback. I was an early Linux user, having done my first install in 1993, and sadly ran Windows on my desktop then because the Linux desktop experience was awful.

Re: Apple’s Darwin OS and XNU Kernel Deep Dive

#150

Post by icedchai »

SG- wrote: post #110
opengears wrote: post #75

Does this give us any indication on when Apple will be ditching x86 support?

any day now, usually after 6-7 years after hardware releases.

We probably have a few more years to go then. Consider that they were still selling Mac Pro 2019 Intel systems as late as June, 2023.
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