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lmm

47,766 karma · joined October 14, 2011

I'm known as m50d some places, including github; my blog (such as it is) is at https://m50d.github.io/
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lmm··on How Japan's railways stayed one while splitting apart
> There are around 100 train companies in Japan. JR is 7 of those 100. The other 93 are NOT JR. Drawing any conclusions about Japanese trains from inspecting 7% of them is just wrong.

JR is a whole lot more than 7% of trains (downthread you claim 38% of passengers, but even that understates things; over 60% of passenger-km are with JR).

> Eiden

Not what it's called lol.

> Those others, except maybe 1, are all private, and have always bene private.

Yes and no. Other operators are structured as private companies but often have significant public ownership, and even those that are notionally 100% privately owned often have strong ties with the political system via the keiretsu system, and always collaborate very closely with local and national governments in practice. E.g. fares are regulated, not simply set at "what the market will bear" levels; conversely the government provides a lot of legal support and subsidy for building new lines.

lmm··on McMansions 101: What Makes a McMansion Bad Architecture? (2016)
Criticising poor usability is fine, worthwhile even. Criticising unfashionable taste is just classism.
lmm··on Tesco moving 40k server workloads off VMware amid Broadcom's abusive conduct
Honestly the writing was on the wall for the traditional VM business already. May as well squeeze out what you can where you can.
lmm··on Tesco moving 40k server workloads off VMware amid Broadcom's abusive conduct
Walmart had already ruined ASDA to be fair, it's not like private equity is doing worse.
lmm··on How memory safety CVEs differ between Rust and C/C++
> it must hold that that a->m->t == b->t.

So define a wrapper type that represents that invariant (it's not going to take up space at runtime), where the only constructor enforces it?

> Integer x is representable using 12 bits only, Integer y should be a multiple of N and I have a integer s is used as a bit-shift that should be less than 8.

Those are all standard things that already exist?

> Or: I need to guarantee that no locks have to be taken and no allocations have to be made on this complicated looking codepath. While holding a lock, we must not do any syscalls (syscall a, b, c are ok though), and surely not make any logging calls.

Sounds like a pretty standard free monad case? Define a command algebra in which the "ok" syscalls are a subtype, and then require that the thing you want to only use the ok calls to have a type that reflects that?

lmm··on Is Meta destroying its engineering organization?
> Handlebars/mustache was what early angular/react used for templating.

Yeah and they migrated away from it for good reason.

lmm··on Stop Using JWTs
What do you do about availability? AFAIK the choice is to pick one of 3 or 4 hacky difficult-to-administer clustering solutions, or have that single PostgreSQL database be a SPOF for your whole system.
lmm··on How memory safety CVEs differ between Rust and C/C++
No, people focus on a handful of things like null, buffer overrun, and use-after-free because they still make up the majority of security vulnerabilities that we see exploited in the wild. You may imagine that subtle logic errors are more common, but the data doesn't bear that out; also FWIW I've never seen one of these detailed invariants be impossible to express in a type system if you spend 5 minutes actually trying.
lmm··on How memory safety CVEs differ between Rust and C/C++
> You cannot save the world from scratch in every little function. You still have a job to get done, and you have to move on.

Or you can take all of 10 minutes to put sanity-check assertions at the start of all your public-facing API functions, eliminating a source of security bugs, get on with your life, and worry about the performance implications as and when it becomes a problem (hint: it's never going to become a problem).

lmm··on How memory safety CVEs differ between Rust and C/C++
I don't understand your comment - dereferencing a null pointer is unsafe, in the sense that it does not reliably crash but may do other things, as we saw in the kernel case we're talking about. Yes that particular case was only exploitable if you mapped the zero page, but given how all-bets-are-off a situation it created (where extremely experienced programmers thought they knew what the code did, thought it was safe, and were wrong), I would not want to count on all cases not being exploitable without mapping the zero page.
lmm··on How memory safety CVEs differ between Rust and C/C++
> In general on a system where you trap when accessing the zero page, this optimization should be safe and a null pointer dereferences should (safely) trap.

If you mean that C compiler writers "should" prioritise sanity over high scores on microbenchmarks, then I agree. However in practice they do not and this optimization is not remotely safe.

lmm··on How memory safety CVEs differ between Rust and C/C++
> it's >> 99.9% true that this will just crash even though it's acshually UB, nasal demons and so forth.

Is it though? Linux saw enough bugs from that kind of issue that they now build with -fno-delete-null-pointer-checks and accept the (supposed) performance penalty.

lmm··on US-Canada border library gets new Quebec-only entrance
> Seems like you just validated my point - a place without open borders is where a major outbreak of xenophobic violence is occurring, as opposed to mainland Europe.

We know exactly what caused this outbreak of xenophobic violence, it's in direct response to a dramatically brutal attempted murder by an immigrant caught on video (one who had been granted a refugee visa, on legitimate grounds or otherwise). That's hardly an argument for open borders - if anything it's an argument for stricter screening of asylum seekers.

> I'd be curious to know what this looked like at the time.

A shift in sentiment, certain kinds of comments being heard more and more, ultimately Brexit.

> even if we accept it as an example, that doesn't set the rule or show a general causation between open borders and xenophobia

At a certain point you experience enough correlations that you have to trust the evidence of your own eyes.

lmm··on Vinyl succumbs to Loudness War: more than just collateral damage (2025)
> I am not insane so I did not spend $1300 on a used vinyl record, I found mine for $2 at Goodwill.

How is holding onto it instead of selling it for $1300 any less insane than buying it for $1300 in the first place?

lmm··on Software is made between commits
Why do you want those commits though? In my experience people only look at history a) to see who wrote the code / when it was last changed, which works equally well with any approach, b) to see which feature it was part of, for which you will click through to the PR anyway, or c) to bisect for when a bug was introduced, in which case unedited/unrebased "noise" commits are more useful because you have more guarantee that each commit compiles and the original train of thought is more useful than the fictional history when you're looking for something unintentional.
lmm··on xAI is looking more like a datacentre REIT than a frontier lab
That's a completely different claim from the one you were making in your previous comment.

> avoid changing any of the circumstances that cause the behavior

The normalisation of unsafe driving is the circumstance that causes the behaviour. Just look at how the cultural shift in how drink-driving is perceived over the last few decades has changed the rate of it happening.

lmm··on Sequoyah’s syllabary created a written language for the Cherokee
Some have. But certainly many continue to use letters beyond those 26, despite the difficulty of using those letters in various technologies.
lmm··on US-Canada border library gets new Quebec-only entrance
> I live here, I think I'd notice if events like the current Belfast riots happened on a more regular basis.

The island of Ireland has had pretty low immigration (not to mention not even having open borders in the sense usually meant by "Europe has open borders", other than between a pair of neighbouring countries with very strong cultural ties), if that's where you mean by "here" you may have been insulated from it. Where I was, while it didn't spill out into rioting (mostly) there was a palpable uptick in xenophobia when Romania and Bulgaria were admitted into the EU, and another with the 2015 migrant crisis (which ultimately lead to many of those open borders being closed, temporarily or "temporarily").

> I'm from there, so I'd be interested to know what time period that would be?

Pre-1902; one could haggle over the exact date depending on what one considers an open border.

lmm··on US-Canada border library gets new Quebec-only entrance
> hasn't facilitated any increase in xenophobia that I'm aware of

Then you haven't been paying attention.

> South Africa by contrast does not have open borders, and is currently going through another bout of violent xenophobia.

Arguably a legacy of the time when it did.

lmm··on I'm Eric Ries, author of "The Lean Startup" and new book "Incorruptible" – AMA
> the claim that something by itself is enough has to explain why most companies are able to be destroyed, even though they have really good leadership

I think most of us are happy to believe that most companies simply have bad leadership, that leadership quality really is the axis on which Costco differs from others. If you want us to believe that other (destroyed) companies' leadership is just as good as Costco's, you need to make that case.

> Costco is protected by a very distinctive thing I call a "governance fortress." This fortress (and not merely their leadership) is the reason why they have been able to endure for forty years.

Can you sketch out your actual argument here (I think doing so would help rather than hinder your book sales, though of course that's a biased judgement)? What is this "governance fortress", and why should we believe that that, rather than the personal qualities of this one guy, is the reason they kept the hot dog?

lmm··on Sequoyah’s syllabary created a written language for the Cherokee
And yet other languages have managed to resist those simplifications. So it's clearly not 100% forced.
lmm··on A Farmer Donated Land to Turn into a Park. The City Is Building a Data Center
It all makes sense once you realise the purpose is to maximise the amount of car storage. You're allowed to build car storage in every zone. Many zones even have a minimum amount of car storage required to accompany anything else you want to build.
lmm··on All 9,300 Japanese train station, animated by the year it opened (1872–2026)
Friedrichstraße was famously like that during the Cold War (West Berliners riding the lines were not permitted to exit into East Berlin), although of course the stairs physically existed. I think it's unusual for an underground station to be built without digging from the surface, so there's normally at least a fire escape.
lmm··on Why SpaceX 2040 Revenue FCST $4.3T in highly unlikely
I'm upset that we allow people like you to avoid paying their fair share of taxes, possibly indefinitely, so anything that makes that harder even "accidentally" is ok by me.
lmm··on WWDC 2026: Apple is Folding
If the alternative is carrying a tablet then a folding phone is smaller.
lmm··on Surprise, pay $1000
Holy shit, all that and then they paid? Worse, decided to use this product on an ongoing basis? I'm not sure who I hate more, Blacksmith for doing this or OP for being such a doormat about it.
lmm··on Let's Encrypt bans certificate usage in any US sanctioned territory [pdf]
Meh. You can fall back on might makes right and a Hobbesian war of all against all, or you can recognise that the Westphalian system has brought immense value to humanity and is worth trying to preserve and build on. There will always be disputes about how to extend our principles into new domains, but that doesn't mean those disputes are insoluble or that a few disagreements mean we should tear down the whole project.
lmm··on Let's Encrypt bans certificate usage in any US sanctioned territory [pdf]
> GDPR

Only applies to EU citizens' personal data, so while technically extraterritorial it doesn't feel like overreach in the same way.

> Universal jurisdiction laws

Rightly controversial when applied beyond things that are internationally agreed to be crimes against humanity, like torture or genocide.

> China's National Security Law

A perfect example of the kind of thing that the US used to define itself in opposition to.

Nations are sovereign and those with the might to push their requirements on others can do so. But I liked it better when we had a sense of the value of an open international order, where things like internet protocols were shared standards that everyone would collaborate on other than a handful of pariah states.

lmm··on Let's Encrypt bans certificate usage in any US sanctioned territory [pdf]
US sanctions law saying that you must not transfer X from the US to Iran, directly or indirectly, is reasonable. US sanctions law saying that you must not transfer X from Brazil to Iran is gross overreach. Yes, of course the US can apply its absurdly extraterritorial laws to any parent company in the US, just as Iran could penalise any Iranian company whose US subsidiary distributed a depiction of the prophet or whatever, but that doesn't make it good law or good practice.
lmm··on Let's Encrypt bans certificate usage in any US sanctioned territory [pdf]
There are many autoantonyms in traditional English, e.g. cleave.
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