I am, of course, assuming that Thunderbolt controllers contain an IOMMU, but given that it has to function as a nontransparent PCI bridge when attached between two computers, that should be a safe assumption.

The whole point of requiring every driver to call the prepare method on an IOMemoryDescriptor object before telling a device to do DMA and calling the matching complete method when the I/O is done is so that the OS can create and tear down mappings in various IOMMU hardware to protect the system as a whole from buggy devices (and particularly those that don't understand 64-bit address spaces). If that isn't happening, I'd argue that it is a kernel bug, and given the security implications, a pretty serious one.

Thunderbolt is rather different, because the devices are basically PCI-E cards with a Thunderbolt transceiver bolted on. As such they can do anything that a PCI-E card can do, including accessing all RAM. PC Card devices have the same issue, and so does Firewire. It's a serious issue and tools that exploit it have been available for a while, both open source and commercial.

Here's what I don't get. Back when the G5 came out, Apple used a custom piece of hardware called DART to create a boundary between the I/O address space used by PCI devices and the physical address space used by RAM. It required device drivers to explicitly configure mappings before a PCI device could scribble on RAM, and limited those devices to scribbling over the ranges specified by the OS. That hardware went away with the Intel transition, of course, but most of the newer 64-bit Intel hardware has a feature called VT-d that does essentially the same thing. AFAIK, the 64-bit OS X kernel uses that functionality by default if the hardware supports it, so all of those tools should be completely non-functional on recent Macs running Mountain Lion and later. And I think I remember reading somewhere that Thunderbolt controllers contain an address translation table as well.

With that in mind, how is this Thunderbolt device somehow gaining the ability to tickle hardware that probably doesn't live on the PCI bus, on the opposite side of the Thunderbolt controller, at a location that wasn't explicitly configured for DMA by a device driver? Does it involve rebooting the machine and exploiting a driver bug in EFI?

Err. Rocket is from the guys that brought you CoreOS. CoreOS uses systemd. Not the same thing.

Heh. I'll show you. I haven't updated my preferred roaming list since 2003. My ancient flip phone will never even see your tower!

On the other hand there is only so much wireless spectrum available that is set aside for 802.11x. Ever been to big even in a hotel where eveybody and their brother has the hot spot function enabled on their phones, is caring around those mobile hot spot things, folks are running classes in conference with their own wireless AP setup for their students, etc.

IIRC, cell phone hotspots deliberately limit their maximum gain to minimize interference. They typically have an indoor range of about 66 feet—essentially, your hotel room and one or two rooms on either side. Based on that, I suspect that those personal hotspots are more likely to be a symptom of the problem than its actual cause.

If you're seeing poor performance on a hotel's infrastructure Wi-Fi network, odds are good that either:

• The hotel doesn't have enough APs.
• The hotel's external bandwidth is insufficient for the traffic.
• The hotel's DHCP server ran out of IP addresses for the number of clients.
• The hotel's DHCP server is buggy and sends out offers based on what the client asked for, without properly checking that the request is sensible (e.g. that it is in the right subnet, that no other client is using that address, etc.).
• The hotel's systems are, in fact, down.

The first one is usually the main problem. Most hotels' networks were designed under the assumption that folks will have at most one Wi-Fi-capable device per room, and that most folks won't be using them at any given point in time. When you have a bunch of geeks with three or four devices, all talking at once, the spectrum can get clogged pretty badly.

There are two possible fixes for that problem. The first fix is to deploy 802.11ac more broadly. For clients that support it, this reduces congestion considerably, both by providing more channels and by reducing interference through beamforming. The second fix is to greatly increase the number of 802.11b/g APs (and, to a lesser degree, 802.11n APs) so that you can reduce their maximum receive and transmit gain settings, effectively creating a large number of very small clusters of nodes instead of a few big ones. Note that these solutions are not mutually exclusive.

Because they don't allow you to bring your own drinks and snacks...and you don't want to be "forced to purchase theirs at a dramatically inflated price". I'm just curious how strong your principles are.

That's not really a fair comparison, for several reasons:

• Movie theaters are considered public locations. Hotel rooms are considered private locations. Just as a hotel cannot authorize the police to search your hotel room without a warrant, it also has limited authority to govern what you do in your room, so long as your actions do not cause damage to the room.
• You stay in a movie theater for the duration of a single movie. Unless your metabolism is insane, you can trivially eat before you go inside and wait to eat again until after you leave. By contrast, you stay at a hotel for several days. Going without Internet service for a week is usually a much bigger burden than going without snacks for 90 minutes.
• Health code regulations often prohibit businesses that sell food from allowing outside food to be consumed on the premises, so even if theaters wanted to allow you to bring food in, they may not be able to do so.
• Movie theaters charge high prices on food to make up for their miniscule profit on movie tickets. Hotels that charge hundreds of dollars per night are making a lot more than a buck per person, so they really don't have any good excuse for ripping people off by charging $15 per day for Internet service.

So although they might be similar in principle, the differences in practice are so large so as to render one a meaningless annoyance that we can live with, while rendering the other a serious act of interference that cannot be tolerated.

But he did film it, kinda. He just didn't put it into the story. It shows up a little bit in the Mirror of Galadriel sequence.

One could argue that that was the correct way to play it, too. I know people who claim to have "walked out of the theater after the first ending and skipped all of the other ones," as it is.

Yeah, on my set there are two settings that combine to create the effect and I have each set to "most of the way off" because that's the way I like it.

There are legit reasons they would want to block all those random wifi hotspots. All those random hotspots are (or could) degrade the performance of the service they are offering. The air does not have unlimited bandwidth. If they knock out all the "rogue" hotspots, they *could* manage the airways within their building better.

Except the reality is that all of those random hotspots are almost by definition physically closer to the user than the ones provided by the hotel, which means the two Wi-Fi radios are likely to be using less power, and thus producing less interference than an extra guest on the hotel's network would produce, not more.

No, there's no legitimate reason for doing this. The only reason they do it is so they can charge as much for one day of service as most people pay for half a month. And yes, I often choose lesser hotels that offer free Wi-Fi over nicer hotels that charge for it. I consider Wi-Fi service to be a basic necessity, and hotels that don't build that into the cost of doing business are not effectively serving my needs.

If a hotel blocked my Wi-Fi hot spot, I would very likely leave their jamming range, go on Hotels.com, leave a negative review, book a different hotel, then go to the front desk and demand a complete refund of the cost of my room. If they refused, I would stand right in front of them while I called my credit card company and issued a charge-back, so that there could be absolutely no doubt in their minds why I did so. I don't care how nice your rooms are. If you're deliberately interfering with my ability to get things done solely so you can make a quick buck, you are not a hotel that is worth staying in.

It seems people don't get this, so let's spell it out:

Inflation requires both demand and supply of money. You can't cause inflation simply by increasing the money supply, unless you go totally crazy with it - however, if that supply is there when the economy heats up and demand appears, look out.

Hpwever, 5-10% inflation during a good economy isn't per se a problem: high inflation is a symptom of a bubble economy but may be there without the bubble. And it's the malinvestment associated with a bubble that hurts everyone - "medium" inflation only really hurts people who made the wrong bet on the future value of the dollar.

As long as you don't actually crater the currency, inflation is merely a warning sign of the real problem, and the real problem is people working on things no one wants: from bubbles to government make-work, the stuff we have is just the stuff we make, and if we're not working to make stuff we want or need, we'll all suffer for it.

So the guest is paying to offer Wi-Fi to people, and the hotel might require that the guest instead pay for the hotel Wi-Fi service.

That simply isn't a reasonable thing for a hotel to do. You would never accept a hotel requiring you to wear only hotel-provided clothing in a conference room. How is requiring you to use their Internet connection instead of a connection that you have already paid for any less absurd?

That search for the lowest place without rats in the toilet is why they do bs like this... they have to compete on "price" and then once you're in make up their money on crap like charging you for internets. Works the same way with airlines, and that's why airlines suck now.

See, that's the opposite of my experience. I've never seen a $50-per-night hotel that didn't offer free Wi-Fi. It's the $300-and-up-per-night hotels that charge $15 a day for Wi-Fi. These same hotels also charge five bucks for a tiny little can of Pringles, four bucks for a soda, etc. Basically, they assume that anybody with enough money to stay in those hotels also can't be bothered to walk downstairs and across the street to the gas station to buy a soda.

And the more expensive the hotel, the more likely they are to use a complex Wi-Fi system that requires you to sign in through a captive portal, breaks in fascinating ways, and is horribly unreliable. The cheaper the hotel, the more likely they are to just toss up a halfway decent trunk line connected to a handful of off-the-shelf Wi-Fi base stations, and be done with it. Guess which one actually works reliably? (Hint: It isn't the complex, expensive systems used at the high-priced hotels.)

As for when hotels should be allowed to block Wi-Fi, the correct answer is "never". It is never acceptable to deliberately cause interference with properly licensed hardware operating in a normal manner. It is illegal, unethical, and any hotel doing so should get buried in fines so high that nobody else ever even thinks of committing such an act in the future. Now if those Wi-Fi hotspots are operating incorrectly and causing interference, it is within their right to use passive mechanisms to track them down and ask the customers to stop using them. However, the burden of proof falls on the hotel chain to prove that those hotspots are, in fact, not operating correctly, and that the problem is not caused by the hotel's Wi-Fi network being set up incorrectly (which it almost certainly always is in any of the sorts of hotels that would attempt such jamming).

I wish I knew a good one! Most places are as crazy as ZeroHedge, in one direction or another. I read MarketWatch, but more to keep abreast of market fashion than reality (never read a stock market site for economic news).

The most useful stuff I've ever read on economics was the old-school stuff: on the business cycle, not just boom-bust but which sectors recover in which order - what leads recovery, and what's big when the end of the boom is near, and what survives best during the bust. The history of different kinds of currencies and the problems the had. The various big name economists from the first half of the 20th century, now that we can see the actual economic growth in various countries that seem to follow on or another of them. Everything old is new again.