Talk:1938: Meltdown and Spectre

The "trolley problem" is the ethical dilemma thought experiment where an out-of-control trolley is heading to a junction (which you have control over) - to one side it'll kill one group of people - to the other, some others. Your moral dilemma is deciding which is the "best" outcome (eg, hitting a dozen five year old children or three Nobel laureats). This is like a software "if" statement. Speculative execution in most CPU chips is where the computer always takes both sides of a decision like this - explores what will happen down each path - and only causes the effects of the decision to happen when the decision as to which way to proceed is decided. This allows it to keep on doing useful work while some slower decision is made. The "quantum" aspect of this is that in some versions of quantum theory, quantum-level particles take every possible path at once and the result is the sum of all of them.

In a sense, the computer is exploring the consequences of the trolley problem in a quantum-like manner.

There's so much wrong with this sentence. You totally did it intentionally. 108.162.216.118 05:56, 7 January 2018 (UTC)

This would all be OK if it were not for the fact that devious black-hat hackers can come up with devious ways to see the information that should have been discarded in the "path-not-taken". So even though the computer will eventually decide that some piece of information should not be accessible - you can find out the value it would hypothetically read - even though it will soon decide that it should not access the information.

The "rowhammer" problem is something entirely different. Computer memories are organized as a two-dimensional grid of rows and columns - and are physically constructed from tiny capacitors. If you apply just the RIGHT pattern of rapid changes to one row of the grid, you can cause one of the capacitors on the next row to incorrectly change state. This is a design flaw in the memory chip - and it allows (in some circumstances) programs to change data in memory locations that they have no right to change.

SteveBaker (talk) 19:33, 5 January 2018 (UTC)

uhhh did you just copy and paste your entire edit into talk? DPS2004'); DROP TABLE users;-- (talk) 20:19, 5 January 2018 (UTC)

Pretty much. When I got here, there was no information about the comic at all. Since I'm unfamiliar with all of the other stuff that goes into an explain, I left it as a comment so someone else could use it...but after a while, nobody did, so I copy-pasted it into the explanation...with some tweaks! Sorry if that was a faux-pas of some variety! SteveBaker (talk) 21:53, 5 January 2018 (UTC)

What? Servers are vulnerable to actual hammers? Huh, do you suppose they're be vulnerable to an actual trolley as well? I have a spare server, does anyone have a spare trolley? ~~ SiliconWolf

My server is actually mounted inside a trolley - precisely to avoid this kind of issue. SteveBaker (talk) 23:02, 5 January 2018 (UTC)

I wouldn't recommend that. A collision would anger the honeybees. ~AgentMuffin

Do you think we can put a quantum computer in a trolley and ask the ghost in the shell to chase down the one causing the above vulnerabilites? 141.101.69.87 11:05, 8 January 2018 (UTC)

The most helpful technical explanation I’ve found is here: https://www.raspberrypi.org/blog/why-raspberry-pi-isnt-vulnerable-to-spectre-or-meltdown/ ;the comments also provide useful clarification. PotatoGod (talk) 02:54, 6 January 2018 (UTC)

Could an explanation be added as to what a trolley is? Being in the UK, my first thought was that of a shopping trolley (US: Shopping cart). Over here, we call trollies "trams" 162.158.34.4 11:39, 6 January 2018 (UTC)

The analogy is the same, just the speed and engine that changes. 162.158.74.9

...As does the lethality... I expect the worst case scenario to be a bruised hip. In fact I'd send a shopping cart at the 5 people, they'd have a greater chance of stopping it without harm. :) NiceGuy1 (talk) 04:09, 7 January 2018 (UTC)

Actually, I find "trolley" to be a very UK word. Outside of this Trolley Problem I never hear it here in North America. Without looking it up, I would expect the mere name means it probably was thought up in the UK in the fist place, or by someone using UK English to name it. Only other term I can think of right now is "streetcar", but I never hear that either. Blanking on what they usually are called (perhaps "tram" as well), but they don't have any anymore in my city. This commonality of terms might be different in cities equipped with them. :) NiceGuy1 (talk) 04:09, 7 January 2018 (UTC)

I totally expected "Schrodinger's Cat's Cat" to be a popular meme, but apparently it is not. Google search I hereby claim it.These Are Not The Comments You Are Looking For (talk) 08:18, 7 January 2018 (UTC)

The explanation assumes Cueball is taking Ponytail's comment litteraly while she agrees with him because of the humor. To me it rather looked like Cueball was making a joke that Ponytail agreed to. The fact that he said "The Cloud" would confirm this view IMHO, as he deliberatly chose another metaphor to push the silly image even further. 141.101.69.87 11:05, 8 January 2018 (UTC)

Thoughts by someone who just arrived

I just read the available explanation, and it seems fairly complete to me, someone who knew next to nothing about spectre and meltdown besides their names before reading. In my opinion, the 'something seems to be missing' tag can be removed. However, as I am no expert on the matter, I will leave someone else to decide and perform (or not perform) the action of removing it. 172.68.65.186 02:30, 8 January 2018 (UTC)

I agree it is almost complete. Have added a missing piece to the incomplete reason. or once here was a subject I did not really know much about (except the trolley prolem ;-) and it was a neat explanation people have made. Thanks. --Kynde (talk) 13:25, 8 January 2018 (UTC)