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roca

5,692 karma · joined October 28, 2014

Robert O'Callahan. Christian. PhD from CMU (2001) in static program analysis. Former Mozilla Distinguished Engineer. Primarily worked on Gecko layout and rendering. Started https://rr-project.org and currently maintaining it. Cofounder of https://pernos.co, an omniscient debugger that people actually use. Google.
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roca··on Starship Flight 5: Launch and booster catch [video]
Both. A single person can be great in some areas and a malicious loon in others. In fact, great success in one field can provide the self-confidence and capital to be a catastrophe in others.

But also keep in mind that Musk isn't personally designing and building everything SpaceX does. The staff at SpaceX deserve more credit than they get, especially Gwynne Shotwell.

roca··on "Begin disabling installed extensions still using Manifest V2 in Chrome stable"
> they should be moved to the front of the tab bar and be protected from closing.

Firefox pinned tabs are moved to the LHS of the tab bar, they have no close button and ctrl-W doesn't close them. How much more do you want them to be protected from closing?

This is actually one thing where Firefox is clearly better than Chrome ... Chrome pinned tabs close with ctrl-W which is really easy to do accidentally.

roca··on "Begin disabling installed extensions still using Manifest V2 in Chrome stable"
Google spent astronomical amounts of money advertising Chrome, including pushing Chrome from literally priceless Web real estate like the Google start page, bundling deals with e.g. Flash, and preinstalls on various desktops and laptops. It really is hard to say what would have happened without that advantage.
roca··on Bridge to Nowhere
I'm a Christian, I lived in the USA for ten years, and AFAIK I never met a single Christian who would deny that mental illness is real or who would say that locking up or torturing mentally ill people is a good thing. And I expect most of them believe that demonic possession can also happen. These are not mutually exclusive beliefs.
roca··on Comparing our Rust-based indexing and querying pipeline to Langchain
Oh, you mean vendoring. Yes, you can do that, but there is no easy support for keeping those vendored dependencies in sync with upstream. And if you want really nice things like notifications when those dependencies have security updates that you need to apply --- forget it.
roca··on Comparing our Rust-based indexing and querying pipeline to Langchain
Build.rs is great on most cases. The important thing is that it's easy for users to download and build everything.
roca··on Comparing our Rust-based indexing and querying pipeline to Langchain
That doesn't solve the problem of making it easy for people to download and build the dependencies.
roca··on Comparing our Rust-based indexing and querying pipeline to Langchain
Lots of reasons, but a big one is that dependency and build management in C++ is absolutely hellish unless you use stuff like Conan which nobody knows. In Rust, you use Cargo and everyone is happy.
roca··on Is the world really running out of sand?
I have a theory that a lot of journalists really wanted to be novelists. When they get a chance to write a long-form article they can't resist the urge to flex their stylistic muscles; "look at me, I'm a Serious Writer".
roca··on Fraud, so much fraud
The problem is that detecting fraud is fundamentally harder than generating plausible fraud. This is because ultimately a very good fraud producer can simply produce output that is identically distributed to non-fraud.

For the same reason, tools that try to detect AI-generated text are ultimately going to lose the arm's race.

roca··on Ask HN: What runs L4-related microkernels/hypervisors these days?
Hmm, but

> The multicore kernel uses a big-lock approach, which makes sense for tightly-coupled cores that share an L2 cache. It is not meant to scale to many cores,

roca··on Eliminating Memory Safety Vulnerabilities at the Source
What does "enforce the use of smart pointers" actually mean? Idiomatic C++ uses "this" and references ubiquitously, both of which are vulnerable to use-after-free bugs just like raw pointers.
roca··on We're not going to run out of new anatomy anytime soon
This is a very interesting observation. I wonder if there's a way to identify the contribution of that initial cellular environment to the phenotype. I guess you could do experiments where you tamper with the initial cellular environment or the DNA and see what happens.
roca··on Ask HN: What runs L4-related microkernels/hypervisors these days?
Is there a verified SeL4 that supports multi-core yet?
roca··on We're not going to run out of new anatomy anytime soon
The incredible complexity of anatomy is even more amazing considering

* all the structures grow from a single cell

* somehow it's all encoded in DNA (only 6 billion bits in humans, which has to also build cells and their ultracomplex machinery)

* this all had to evolve using only a very noisy objective function

roca··on Profiling with Ctrl-C
If you do try doing that, use rr's "chaos mode".
roca··on My fake job in Y2K preparedness
There is a very powerful myth taking hold that the Y2K problem wasn't real, but some kind of false alarm or scam. It's very strange and scary. It's not just isolated people getting it wrong, I see it popping up all over the place. We really need to push back on it.
roca··on Deterministic Replay of QEMU Emulation
It was removed in 2011.
roca··on Make Firefox Private Again
It's actually: you say you want to live in a world where there are no ads, and therefore no ad-supported content. Well, with a little self-restraint you can live in that world right now. What, you don't like that world after all?
roca··on Make Firefox Private Again
Then I think it's only fair for you to completely stop using ad-supported sites and services, right away.

(Which will also mean that Firefox's treatment of ads will not affect you.)

roca··on Make Firefox Private Again
> I don't think there can be a technical solution to this problem unless advertisers are forced by government regulations to behave, with very heavy fines for non-compliance.

Indeed, but such regulation is much more likely to happen if there already exist privacy-preserving solutions like PPA.

"There's a good way to do it and a bad way, and we're making it illegal to do it the bad way" vs "There only way to do it is bad, and we're making that illegal, so sucks to be you"

roca··on Debugging operating systems with time-traveling virtual machines (2005) [pdf]
The Linux kernel supports pretty powerful APIs for inspecting and managing processes, like ptrace and seccomp and /proc, from another userspace process. There is no comparable set of APIs for hypervisors, unless Xen has something maybe?

And we don't handle unrestricted multithreading in rr. If we wanted to it would complicate things a lot and I don't know if existing kernel APIs would be adequate. We're skating along the edge of feasibility as it is.

roca··on Debugging operating systems with time-traveling virtual machines (2005) [pdf]
The assumption here is that you're modifying the hypervisor itself. No-one expects to be able to bolt a record-replay tool onto a third-party hypervisor.
roca··on Debugging operating systems with time-traveling virtual machines (2005) [pdf]
The interface between userspace processes and the kernel and CPU is pretty complicated. It's hard for me to tell whether it's more or less complicated than the interface between guests and the hypervisor (given most record and replay scenarios don't require virtualizing exotic hardware).

It probably is easier to debug rr replay bugs than VM-level replay bugs, partly because rr is lighter-weight. rr replay bugs are still insane, but it's all relative :-).

roca··on Debugging operating systems with time-traveling virtual machines (2005) [pdf]
My instinct is the same as yours, but I'm also well aware of the "grass is greener on the other side of the fence" cognitive bias :-). So without actually having written a record-and-replay hypervisor, I hesitate to judge.
roca··on The brain simulates actions and their consequences during REM sleep
Makes sense to me. I organise a lot of hiking trips and I frequently have dreams where one of my trips has gone wrong and I'm trying to cope. It's a cheap way to simulate a problematic situation.
roca··on Debugging operating systems with time-traveling virtual machines (2005) [pdf]
I wonder if this inspired the VMWare VM record-and-replay functionality that came out in 2008. They discontinued it in 2011, but it's important to me because we used it at Mozilla to great effect and that made it easier for me to get Mozilla to support the development of rr, which started in 2011.
roca··on Kim Dotcom's extradition to the U.S. given green light by New Zealand
Dotcom did absolutely nothing to "upset people with power". He was always just an obnoxious hustler trying to make money by obviously illegal means.
roca··on Google Pixel 9 Pro
Charging a fee for using it is a bad idea because then people will delay using it until it's too late.

That's why in New Zealand, at least, there is no fee for a rescue callouts in general.

roca··on Translating All C to Rust (TRACTOR)
Bounded model checking is not a silver bullet. If you want to prove it is, verify a Web browser and blog about it.
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