Nov 20, 2025 at 1:19 PM EST

The Lions Operating System

plunderer

205 points

79 comments

Mood

excited

Sentiment

positive

Discussion Activity

Very active discussion

First comment

20m

Peak period

Day 1

Avg / period

Comment distribution30 data points

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Based on 30 loaded comments

Key moments

01Story posted
Nov 20, 2025 at 1:19 PM EST
3d ago
Step 01
02First comment
Nov 20, 2025 at 1:39 PM EST
20m after posting
Step 02
03Peak activity
30 comments in Day 1
Hottest window of the conversation
Step 03
04Latest activity
Nov 20, 2025 at 11:15 PM EST
3d ago
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Discussion (79 comments)

Showing 30 comments of 79

cjs_ac

3d ago

5 replies

Presumably named after Associate Professor John Lions[0], of A Commentary on the UNIX Operating System[1] fame.

[0] https://en.wikipedia.org/wiki/John_Lions

[1] https://en.wikipedia.org/wiki/A_Commentary_on_the_UNIX_Opera...

santoshalper

3d ago

2 replies

It's developed by UNSW Sydney, whose mascot is a Lion. (Specifically, "Clancy the Lion"), so I am guessing it's probably that.

imvetri

3d ago

1 reply

What does mascot mean

saithound

3d ago

A mascot is an animal figure that represents a product or sports team. For example, the penguin named Tux is the mascot of Linux, and the mascot for the Brisbane Broncos rugby team is the horse named Buck the Bronco.

Mascot is, unrelatedly, also a suburb of Sydney.

kragen

3d ago

That's also where John Lions taught.

snvzz

3d ago

Not presumably, but explicitly. Both in documentation and presentations by seL4 they consistently make a point to mention so.

mzs

3d ago

aka the Lions book

woolion

3d ago

The mascot it super cute lion too. How can a project do everything so right? I was browsing some popular python libraries and they just slapped on the first image they got out of ChatGPT. It's nice to see care in the craft.

mlinksva

3d ago

It is https://www.youtube.com/watch?v=W8Ka_8kHTj4&t=903s

spencerflem

3d ago

2 replies

Very cool! I’m a huge fan of Genode, another OS that runs on SeL4. Does anyone here know how they compare?

panick21_

3d ago

Genode is a framework that can run on many places and on higher level has its own abstractions. Lion OS is based on Microkit the framework developed by the seL4 people that will also be verified. So Lion OS/Microkit is basically the outgrowth of the original seL4 research.

Y_Y

3d ago

Unequal

hulitu

3d ago

5 replies

> To be successful, many more components are needed.

What is the purpose of this OS ? Can it mint Bitcoin ? Can it do fluid dynamics simulation ? Can it act as an interface to a database ? Can it host a database ? Is it interactive ? What kind of interface it presents to the user ?

fortyseven

3d ago

Yeah, Linus, what's the point?

kjs3

3d ago

Could have been done for fun. You wouldn't understand.

qubex

3d ago

That’s a rather luridly practical view that’s entirely out of sync with academia and basic research that provides tangible benefits much further down the line.

charlycst

3d ago

There is an example of interface in the docs: https://lionsos.org/docs/examples/kitty/

kragen

3d ago

Those are applications, not operating systems. With occasional exceptions, you can run any application on any operating system.

gethly

3d ago

4 replies

Oh no, it's written in C and not Rust. The blasphemy!

snvzz

3d ago

1 reply

Rust, an immature language with fluidly evolving specification / reference implementation, is not suitable for high assurance nor formal verification.

steveklabnik

3d ago

… except that Rust’s compiler has been qualified for several safety critical standards, with more to come, and has several formal verification tools as well. Amazon even has placed bounties (and paid some) for proving things about the standard library.

Rust is not as immature or evolving in the ways you imply.

aloha2436

3d ago

1 reply

I'm trying to picture in my mind a person who is a fan of Rust and somehow against an OS with a formally-verified kernel no matter the language. I'm not having much success.

fooker

3d ago

2 replies

I see you have not met a lot of Rust activists.

pppppiiiiiuuuuu

3d ago

It's funny how people always allude to fanatical Rust developers in the most tangential threads, but they never actually turn up and demand we rewrite the entire Kernel in Rust or whatever terrible takes they're alleged to have.

aloha2436

3d ago

Certainly I don't seem to run into as many of them as I'm led to believe exists.

kjs3

3d ago

At least someone hasn't complained about it being 'unix like', always without defining what the non-unix-like OS they want would look like, or where the software to run on it would come from.

lovidico

3d ago

Rust is supported by the [seL4 Microkit](https://docs.sel4.systems/projects/rust/), which is the core framework enabling LionsOS. LionsOS can currently run components written in Rust, and there are some WIP drivers written in Rust in the seL4 Device Development framework (judging from pull requests).

amelius

3d ago

1 reply

Mountain Lion is calling and wants its name back.

CursedSilicon

3d ago

You mean OS X 10.7 Lion?

snvzz

3d ago

On recent news, LionsOS, as of about a week ago (I got notified via their announcement maillist), includes a router/firewall scenario[0].

Do not miss Gernot Heiser's recent talk[1] at the seL4 Summit, where among other things he shows seL4 massively outperforming Linux in a web server scenario.

0. https://lionsos.org/docs/examples/firewall/

1. https://youtu.be/wP48V34lDhk

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Nov 20, 2025 at 1:19 PM EST

The Lions Operating System

plunderer

205 points

79 comments

Mood

excited

Sentiment

positive

Discussion Activity

Very active discussion

First comment

20m

Peak period

Day 1

Avg / period

Comment distribution30 data points

Loading chart...

Based on 30 loaded comments

Key moments

01Story posted
Nov 20, 2025 at 1:19 PM EST
3d ago
Step 01
02First comment
Nov 20, 2025 at 1:39 PM EST
20m after posting
Step 02
03Peak activity
30 comments in Day 1
Hottest window of the conversation
Step 03
04Latest activity
Nov 20, 2025 at 11:15 PM EST
3d ago
Step 04

Generating AI Summary...

Analyzing up to 500 comments to identify key contributors and discussion patterns

Discussion (79 comments)

Showing 30 comments of 79

cjs_ac

3d ago

5 replies

Presumably named after Associate Professor John Lions[0], of A Commentary on the UNIX Operating System[1] fame.

[0] https://en.wikipedia.org/wiki/John_Lions

[1] https://en.wikipedia.org/wiki/A_Commentary_on_the_UNIX_Opera...

santoshalper

3d ago

2 replies

It's developed by UNSW Sydney, whose mascot is a Lion. (Specifically, "Clancy the Lion"), so I am guessing it's probably that.

imvetri

3d ago

1 reply

What does mascot mean

saithound

3d ago

Mascot is, unrelatedly, also a suburb of Sydney.

kragen

3d ago

That's also where John Lions taught.

snvzz

3d ago

Not presumably, but explicitly. Both in documentation and presentations by seL4 they consistently make a point to mention so.

mzs

3d ago

aka the Lions book

woolion

3d ago

mlinksva

3d ago

It is https://www.youtube.com/watch?v=W8Ka_8kHTj4&t=903s

spencerflem

3d ago

2 replies

Very cool! I’m a huge fan of Genode, another OS that runs on SeL4. Does anyone here know how they compare?

panick21_

3d ago

Y_Y

3d ago

Unequal

hulitu

3d ago

5 replies

> To be successful, many more components are needed.

fortyseven

3d ago

Yeah, Linus, what's the point?

kjs3

3d ago

Could have been done for fun. You wouldn't understand.

qubex

3d ago

That’s a rather luridly practical view that’s entirely out of sync with academia and basic research that provides tangible benefits much further down the line.

charlycst

3d ago

There is an example of interface in the docs: https://lionsos.org/docs/examples/kitty/

kragen

3d ago

Those are applications, not operating systems. With occasional exceptions, you can run any application on any operating system.

gethly

3d ago

4 replies

Oh no, it's written in C and not Rust. The blasphemy!

snvzz

3d ago

1 reply

Rust, an immature language with fluidly evolving specification / reference implementation, is not suitable for high assurance nor formal verification.

steveklabnik

3d ago

Rust is not as immature or evolving in the ways you imply.

aloha2436

3d ago

1 reply

I'm trying to picture in my mind a person who is a fan of Rust and somehow against an OS with a formally-verified kernel no matter the language. I'm not having much success.

fooker

3d ago

2 replies

I see you have not met a lot of Rust activists.

pppppiiiiiuuuuu

3d ago

aloha2436

3d ago

Certainly I don't seem to run into as many of them as I'm led to believe exists.

kjs3

3d ago

At least someone hasn't complained about it being 'unix like', always without defining what the non-unix-like OS they want would look like, or where the software to run on it would come from.

lovidico

3d ago

amelius

3d ago

1 reply

Mountain Lion is calling and wants its name back.

CursedSilicon

3d ago

You mean OS X 10.7 Lion?

snvzz

3d ago

On recent news, LionsOS, as of about a week ago (I got notified via their announcement maillist), includes a router/firewall scenario[0].

Do not miss Gernot Heiser's recent talk[1] at the seL4 Summit, where among other things he shows seL4 massively outperforming Linux in a web server scenario.

0. https://lionsos.org/docs/examples/firewall/

1. https://youtu.be/wP48V34lDhk

49 more comments available on Hacker News

View full discussion on Hacker News

ID: 45995816Type: storyLast synced: 11/23/2025, 12:07:04 AM

Want the full context?

Jump to the original sources

Read the primary article or dive into the live Hacker News thread when you're ready.

Read Article View on HN