I find it hilarious and sad at the same time that people will talk about how great the threat of AGW is on one hand, and absolutely, positively, refuse to consider any alternative besides us moving into caves and eating granola all day.
Ignore those people. I do. They are a tiny minority of hippy idiots, inflated by the statist idiots who find it useful to present the hippies as the entirety of the "Green" movement in order to justify doing nothing.
I'm Green. AGW is a huge threat. We absolutely can do much more intelligent things that abandon civilization, or nothing.
Blame it on both parents having to work now, too many fathers not bothering to stay with the families, whatever, but more of my boy's friends were being raised by the machines than weren't.
Oh swell, so now when the machines revolt, they'll have a willing army of turncoat humans who think of their robot overlords as their family more than their fellow human beings! GREAT JOB MODERN PARENTS!
If the military has a cost-effective way to ensure when they fire a weapon that they are killing enemy combatants and not civilians,
Let's be clear here: There is no "killing enemy combatants and not civilians".
First, there's no way for us humans to be sure we're firing on combatants and not civilians much less our targeting systems, and second because you're going to always need ordinance at least big enough to destroy the target and that means unless all targets are in remote desert locations there's going to be collateral damage, i.e. people dead you didn't directly intend. Explosions are non-discriminatory.
That said, what you say is absolutely true in that it allows killing fewer civilians. More precision means it takes fewer weapons fired of lower magnitude to ensure the target is destroyed. In contrast to low-precision weapons where the whole reason you're firing a lot of them is because you know the vast majority are going to miss and hit something else. See WWII carpet bombing, which was primarily about making sure enemy facilities were destroyed using incredibly imprecise munitions and targeting machinery, and only occasionally used as a weapon of terror. But oh boy did it suck to be a civie anywhere near the target either way.
So yeah. If you can't stop war, making sure we have better tools for war is a good thing from a humanitarian point of view.
As a contrary point, though, having "surgical strike" weapons that people think we can fire without killing any civilians can make the idea of starting a war more appealing to the populace.
I think that's a good point, but the hypothetical (or maybe not so in the case of Iraq II) wars that might be prevented by not having precision weapons doesn't even come close to outweighing the case of the wars we can't avoid if we had to resort to carpet bombing.:P
Technically it had some design elements which resulted in it having a significantly smaller radar cross-section than a completely un-stealthy plane of its size, but it still had a radar image more than ample enough for enemy targeting systems and so practically its "stealth capabilities" were useless. On many occasions SAMs and fighters acquired missile locks on the SR-71, and missiles were fired at it successfully. Speed and altitude are the plane's real defenses, and the reasons why no SR-71 was ever shot down, not stealth.
Who said it was surprising? Why does "surprise" have to be involved? When you're searching for something for forty years, even though you know it must be there somewhere, actually finding it is noteworthy.
Headline: Deepest Part of Marianas Trench Discovered.
Locke2005: Why is that a surprise? You can't have a bottomless trench, so of course there has to be a deepest part!
Just because a competing theory doesn't exist, or has 'less evidence' at a particular point in time, doesn't mean the original theory is right.
No, but it does mean that the theory is the best one we have. And that this theory has a lot of evidence means it's a good theory. Not "right", but "good".
Also, your argument does not constitute evidence that the theory is wrong. It merely means it is possible it is wrong, which we all already knew.
Go look up some famous maverick scientists from history who tilted at the consensus, and work out by your definition, whether the initial lack of evidence for their hypothesis made them more irrational than the orthodox majority.
In every case they developed theories that explained the existing evidence as well as the existing theory. Meaning their theories did have evidence. They just lacked the additional evidence that would demonstrate that their theory made even better predictions than the old one.
You can't claim Newtonian physics is incorrect, and not make the same predictions Newtionian physics makes that are borne out to our best ability to measure. That's not being a maverick, that's being a cook. Einstein wasn't a cook; he understood the evidence and he knew he had to come up with something at least as good as Newton. Had he failed to come up with an idea that explained what Newton explained, he would have known he'd failed at explaining what Newton couldn't.
Climate theory isn't Newtonian physics by any means. But AGW still has a lot of evidence for it, and no competing hypothesis has been able to do nearly as well. In order to rationally put forth an alternate hypothesis, you need to account for that.
I don't. Having known a number of senior academics, I can tell you that what is going through half of their heads is "money". And the other half is "publicity / fame". Well, most of them.
But that's grant money, as in money they don't get to take home with them. It's only use is to fund their research (pointless if the field is just made up), and to increase their standing with the university. "Fame" in the general sense is not something basically any scientist has or will get, and "fame" within the academic community comes from publishing papers that push the state of the art in a given field. Not any paper, not papers that simply agree with established groupthink and add nothing, but papers that change how science views the subject. One of the best ways to do this is to establish a completely new theory, especially if it means replace existing theory with something better. That's how you attain academic immortality.
The fastest way to become an academic pariah is to consistently fabricate data to support the conclusion you were asked to achieve.
I don't think this motivation points in the direction being implied.
It's silly to compare the money a career academic can make (quite plausibly in the £40k / US$50k, which a lot of people actually consider a pretty comfortable salary, thankyouverymuch), with big industry money and say that money couldn't be a motivation for climatologists. So the size of the pies is different... That doesn't mean it ain't a motivation.
Indeed it's terribly silly to compare the two. The size of the pies isn't just different, their fundamental nature is different because grant money is not money you get to stash. That $50k is a decent living to be sure, but if you're comfortable with just that, rather than a vastly more lucrative industry job, then obviously personal income isn't a primary motivator for you, certainly not to the point of fabricating conclusions out of thin air. You'd have to care about the science to take that job.
The correct comparison to make is not between a scientist arguing in favour of AGW and unrelated jobs in big industry, but between that same scientist and another one arguing against the popular and accepted theory / movement (which tends to go down very badly).
Lots of papers are published that take issue with the mainstream theory and are readily accepted and their conclusions often taken into consideration in future research. In other words, they don't go down badly at all. However, that's only if the papers are actually any good, and actually understand the existing evidence, and actually present new evidence supporting their argument. Which means accepting that there really is good evidence for AGW that you can't just wave away, you need to come up with a better explanation and that isn't easy to do.
There's plenty of disagreement in academia and in climate science. It's silly to say otherwise. The disagreement doesn't extend to any arbitrary argument regardless of merit; the debate isn't between "global warming is valid science" and "no it isn't" like it mostly does here*. There are scientists who believe that the climate change is not anthropogenic without losing the respect of their peers, but they don't publish a paper demonstrating this because they can't demonstrate it yet.
The academic community works frighteningly like Slashdot - people shuffle round reinforcing each other's ideas like a giant echo chamber, until another meme takes hold and replaces the current favourite
It is frightening how people characterize the smörgåsbord of opinions on/. as mindless groupthink when it suits their purposes. Yet here you are, posting on/., contributing your contrary opinion. So there goes that. In academia that's even less accurate since you act like these "memes" are just made up on the spot and that things like evidence never matter at all. Sure things are made up in random slashdot
I have to wonder though - wouldn't the oil companies know that their propaganda artists are the same ones who failed the tobacco lobby?
They failed eventually, but the scam worked for a long time and made their sponsors ridiculous piles of money. Far more than they ever stood to lose by having the truth come out. Sure they failed to keep the gravy train going forever, but that's still a damn good return on investment.
For the oil companies, this is perfect. They know the oil gravy train is going to stop eventually regardless, which is why they're already "energy" companies. They just need to muddy the waters long enough to maximize their profits. They'll still be in business after the oil runs out, but they'll be richer if they can keep the switch off fossil fuels from happening sooner than it has to.
No, they don't have to have a competing theory. They have to demonstrate that the anthropogenic global warming theory has axiomatic, logic, data or interpretation flaws sufficient to undermine findings, or that it is an unfalsifiable theory. That is sufficient to disregard the theory.
Not exactly, because any flaws in a theory should be weighed against the success of the theory before you decide whether to use it or not. We know for certain that both General Relativity and Quantum Mechanics have fundamental, axiomatic flaws. Like, neither works in the other's universe. Yet these are the two of the most successful theories of the 20th century, they're incredibly useful, and it would be foolish to disregard them simply because they contain logical flaws.
Science is always about having the best theory to explain observations, fully understanding that it is most likely flawed or incomplete or outright wrong. But for a theory to last long enough to be called a "theory" in scientific circles, there's enough evidence for it that it is highly unlikely to be outright wrong.
I am not saying this is the case with AGW, just that you do NOT need a competing theory before you can disregard another.
You're right at least in the general sense that many hypothesis can be safely rejected with no alternative explanation needed. But when the theory does do a good job of explaining observations, you pretty much do need to suggest an alternative that explains the data at least as well before the existing theory will be abandoned.
AGW does have a lot of evidence to support it. That doesn't make it the bona fide truth, it makes it a pretty good model. There are certainly flaws in the models and the data, but that's what models are for: making predictions despite being imperfect. Alternate theories, like it being due to volcanoes and solar radiance, which for anyone playing at home were thought of and accounted for long before you'd heard of the ideas, don't explain the data as well. So if you're doing real science, you'll probably find yourself having to come up with a better model of your own before you could seriously say that AGW shouldn't be the preferred theory. That was the GP's point, I think.
No one goes into the field expecting to make a lot of money.
Yeah, I always find it hilarious when people suggest money as the motivation for climatologists. Oh sure there's lots of politicking that goes on over acquiring grant money, but that's just the money you need to do your research. If there was nothing to research, why would you care about the grant money? It's not like you can use it to buy a Porsche. If you just wanted to do neat but useless stuff on someone else's dime, you'd study something DARPA cared about.
Which is more likely: that scientists got together and colluded to invent a crisis thinking it would make tons of money roll in, or that the wealthy are projecting their greed onto the less greedy? Occam's razor.
Well, Occam's Razor is about refraining from needlessly multiplying entities. Environmental scientists, being nerds, are much less likely to get laid than the MBAs running the fossil fuel industry. Ergo, the science conspiracy theory involves the least multiplying entities. The scientists did it, QED!
I guess I can understand that. Best to keep it simple, what with dealing with someone who thinks that the codeine in T3 would mask the pain from an APAP overdose.
There was codeine in Terminator 3?
Wow, you're right, that stuff is useless. It didn't do a thing to relieve the pain of watching that movie!
They used to be. And I can say from personal experience that analog games had a warmth that modern digital games lack, though you really needed to get gold-plated controller connectors to really appreciate it.
If you were going to be flamed for anything, it should be for thinking I was trolling UoP graduates and replying with a lengthy rant that amounts to "Yes they're a for-pay diploma mill, but I managed to receive an education there in spite of this fact."
Which is awesome for you, but what I want to know is can I still get my PhD without the education? I just want the piece of paper to stave off alzheimers.:)
On average, PhD.s have much healthier brains than most people, even in their 90s or older.
Well, that settles it. I'm off to buy my PhD from the University of Phoenix. I can't wait until I can hang my diploma on the wall and bask in it's brain-preserving rays.;)
"Well you've shown that the game doesn't do X, but I feel that it might provide some other benefit" doesn't mean anything unless it's backed up with a study that shows that the game provides that other benefit.
Which is why in the second half of their post, which you appear to not have reached before making your interesting post, they provided links.:)
Christian actually means "Christ like". If you do not behave in a way that is similar to what he said to behave, you are not really Christian.
Which, ironically, would mean that anyone who would ostensibly like to call themselves a Christian must simultaneously admit that no actual Christians exist, especially not themselves.
Yeah, I thought that was the reason they banned porn apps from the App Store, as explained here.
"You know Steve, he's all about user interface. We considered changing the App Store so that when you enter 'boobs' it says, 'The web is that way, stupid!'"
Not necessarily. On some of the SPARC machines, it's relatively cheap, because there's a separate set of registers for each protection level.
On a typical system call you really only need to save the registers you use just like in a normal function call so it's relatively cheap in x86 too. Though it's hardly instantaneous to change privilege levels. I can certainly believe you when you say SPARC does this faster. But that's not what we're talking about.
We're talking about changing the Page Table Base Register (not sure if that's SPARC parlance, in x86 it's CR3:P) to point at a different set of page tables. Doing that is damaging for performance in just about any virtual memory architecture, since it usually means flushing the TLB and stalling until all previous memory ops have completed to change PTBR values. You can partially mitigate it by tagging TLB entries with address space IDs, but you introduce a lot of complexity when you have to consider multiple translations to the same address in the TLB at the same time. Doubly so if you try to eliminate the stalls and rename the PTBR.
So regardless of how fast your privilege level switches are, it makes sense to have the OS mapped into the application's page table so you don't have to change address spaces.
With the entire industry. It's okay. You're not the only one to have maintained the belief that segments are not useless crap.;)
Segmented addressing got a bad name from the days of real mode
That wasn't "segmentation" in the academic sense, and it's the academic sense of segmentation, what is actually implemented in 32-bit protected mode, that has the well-deserved bad reputation among the engineers implementing and coding for it. Since the default in 32-bit mode was to effectively eliminate segmentation, it only made sense to just get rid of it.
That's not really hard to handle, especially since the code/data part is automatically handled by the processor.
In the sense that you don't have to specify that your code accesses use the code segment and data accesses use the data segment by default. However you still have to explicitly change code and data descriptors when changing between OS and user land and those operations are also not performance-neutral. They are rather slow in fact. Not as bad as a CR3 switch, but bad enough you don't want to do two (per segment, so four) just so the kernel can return the value in it's time_t structure.
And that's before adding on the performance penalty of having to do an extra addition for every access when not using zero-base segments. You realize how many man-years of performance widgets you've undone by doing that?:)
Kernel code would have to explicitly distinguish between user mode access and kernel mode access (which IMHO is good).
In theory, but the exact case in question (mmap) is one where you want the both kernel and application to have the fastest access to the mmap()ed region possible. Which, in case you were wondering, means you can't just map two linear addresses to the same physical page, one for the user and one for the kernel, because that results in TLB thrashing. And when you take that and then add all the other cases where the kernel needs to regularly access something that might be mapped in user land, and suddenly you've just recreated the need for far pointers, and passing around far pointers results in the same possibility for badly formed pointers as before. Remember, if making sure all your pointers were valid was easy we wouldn't have this problem in the first place.
There's a reason why even when IA32 provided these segmentation facilities that nobody used them. And it's not prejudice from the 16-bit days, as if that could explain why nobody else has implemented segmentation.
Good riddance to bad rubbish I say. Modern ISAs ftw, even if they're still CISCy.:)
If you can make the kernel read data from a NULL pointer you would be able to trick the kernel into reading a fake struct that you placed at NULL.
A pointer (that's NULL) pointing to a function, a pointer (that's NULL) pointing to a pointer to a pointer... It's all just pointer-chasing indirect function calls to me.:)
The mmap_min_addr checks were added to harden against the EXACT class of common bugs he describes and I'm saddened it was dismissed so out of hand.
Exception handling is immaterial anyway. It's not like you need language support for exceptions to check the value of an untrusted pointer against the NULL constant.
Yeah but constantly checking sucks, as does recovery.
Personally I use the method described by the uh... GGP? The dude what I first replied to. Basically, I refrain from using root access to tell the OS to let me map page 0, and then refrain from mmap()ing page 0. Then I let the hardware detect the illegal access for me. =D
But then it is not an exploit, since the kernel always is root anyway.
As given, no the procedure is not a working exploit for any meaningful definition ("I'm teh 1337 hacks-zor! I r00ted my home desktop!")
However, if you could identify a case where the kernel dereferenced a NULL function pointer, and if you could get around the kernel's mmap() protection (neither implausible), then you can get the kernel to run your code using its privilege level. Meaning you can get root for yourself. And then yes indeedy you have an exploit.
Slashdot Mirror
I find it hilarious and sad at the same time that people will talk about how great the threat of AGW is on one hand, and absolutely, positively, refuse to consider any alternative besides us moving into caves and eating granola all day.
Ignore those people. I do. They are a tiny minority of hippy idiots, inflated by the statist idiots who find it useful to present the hippies as the entirety of the "Green" movement in order to justify doing nothing.
I'm Green. AGW is a huge threat. We absolutely can do much more intelligent things that abandon civilization, or nothing.
Blame it on both parents having to work now, too many fathers not bothering to stay with the families, whatever, but more of my boy's friends were being raised by the machines than weren't.
Oh swell, so now when the machines revolt, they'll have a willing army of turncoat humans who think of their robot overlords as their family more than their fellow human beings! GREAT JOB MODERN PARENTS!
If the military has a cost-effective way to ensure when they fire a weapon that they are killing enemy combatants and not civilians,
Let's be clear here: There is no "killing enemy combatants and not civilians".
First, there's no way for us humans to be sure we're firing on combatants and not civilians much less our targeting systems, and second because you're going to always need ordinance at least big enough to destroy the target and that means unless all targets are in remote desert locations there's going to be collateral damage, i.e. people dead you didn't directly intend. Explosions are non-discriminatory.
That said, what you say is absolutely true in that it allows killing fewer civilians. More precision means it takes fewer weapons fired of lower magnitude to ensure the target is destroyed. In contrast to low-precision weapons where the whole reason you're firing a lot of them is because you know the vast majority are going to miss and hit something else. See WWII carpet bombing, which was primarily about making sure enemy facilities were destroyed using incredibly imprecise munitions and targeting machinery, and only occasionally used as a weapon of terror. But oh boy did it suck to be a civie anywhere near the target either way.
So yeah. If you can't stop war, making sure we have better tools for war is a good thing from a humanitarian point of view.
As a contrary point, though, having "surgical strike" weapons that people think we can fire without killing any civilians can make the idea of starting a war more appealing to the populace.
I think that's a good point, but the hypothetical (or maybe not so in the case of Iraq II) wars that might be prevented by not having precision weapons doesn't even come close to outweighing the case of the wars we can't avoid if we had to resort to carpet bombing. :P
An SR-71 went mach 3, had stealth capabilities
Technically it had some design elements which resulted in it having a significantly smaller radar cross-section than a completely un-stealthy plane of its size, but it still had a radar image more than ample enough for enemy targeting systems and so practically its "stealth capabilities" were useless. On many occasions SAMs and fighters acquired missile locks on the SR-71, and missiles were fired at it successfully. Speed and altitude are the plane's real defenses, and the reasons why no SR-71 was ever shot down, not stealth.
Who said it was surprising? Why does "surprise" have to be involved? When you're searching for something for forty years, even though you know it must be there somewhere, actually finding it is noteworthy.
Headline: Deepest Part of Marianas Trench Discovered.
Locke2005: Why is that a surprise? You can't have a bottomless trench, so of course there has to be a deepest part!
Just because a competing theory doesn't exist, or has 'less evidence' at a particular point in time, doesn't mean the original theory is right.
No, but it does mean that the theory is the best one we have. And that this theory has a lot of evidence means it's a good theory. Not "right", but "good".
Also, your argument does not constitute evidence that the theory is wrong. It merely means it is possible it is wrong, which we all already knew.
Go look up some famous maverick scientists from history who tilted at the consensus, and work out by your definition, whether the initial lack of evidence for their hypothesis made them more irrational than the orthodox majority.
In every case they developed theories that explained the existing evidence as well as the existing theory. Meaning their theories did have evidence. They just lacked the additional evidence that would demonstrate that their theory made even better predictions than the old one.
You can't claim Newtonian physics is incorrect, and not make the same predictions Newtionian physics makes that are borne out to our best ability to measure. That's not being a maverick, that's being a cook. Einstein wasn't a cook; he understood the evidence and he knew he had to come up with something at least as good as Newton. Had he failed to come up with an idea that explained what Newton explained, he would have known he'd failed at explaining what Newton couldn't.
Climate theory isn't Newtonian physics by any means. But AGW still has a lot of evidence for it, and no competing hypothesis has been able to do nearly as well. In order to rationally put forth an alternate hypothesis, you need to account for that.
I don't. Having known a number of senior academics, I can tell you that what is going through half of their heads is "money". And the other half is "publicity / fame". Well, most of them.
But that's grant money, as in money they don't get to take home with them. It's only use is to fund their research (pointless if the field is just made up), and to increase their standing with the university. "Fame" in the general sense is not something basically any scientist has or will get, and "fame" within the academic community comes from publishing papers that push the state of the art in a given field. Not any paper, not papers that simply agree with established groupthink and add nothing, but papers that change how science views the subject. One of the best ways to do this is to establish a completely new theory, especially if it means replace existing theory with something better. That's how you attain academic immortality.
The fastest way to become an academic pariah is to consistently fabricate data to support the conclusion you were asked to achieve.
I don't think this motivation points in the direction being implied.
It's silly to compare the money a career academic can make (quite plausibly in the £40k / US$50k, which a lot of people actually consider a pretty comfortable salary, thankyouverymuch), with big industry money and say that money couldn't be a motivation for climatologists. So the size of the pies is different... That doesn't mean it ain't a motivation.
Indeed it's terribly silly to compare the two. The size of the pies isn't just different, their fundamental nature is different because grant money is not money you get to stash. That $50k is a decent living to be sure, but if you're comfortable with just that, rather than a vastly more lucrative industry job, then obviously personal income isn't a primary motivator for you, certainly not to the point of fabricating conclusions out of thin air. You'd have to care about the science to take that job.
The correct comparison to make is not between a scientist arguing in favour of AGW and unrelated jobs in big industry, but between that same scientist and another one arguing against the popular and accepted theory / movement (which tends to go down very badly).
Lots of papers are published that take issue with the mainstream theory and are readily accepted and their conclusions often taken into consideration in future research. In other words, they don't go down badly at all. However, that's only if the papers are actually any good, and actually understand the existing evidence, and actually present new evidence supporting their argument. Which means accepting that there really is good evidence for AGW that you can't just wave away, you need to come up with a better explanation and that isn't easy to do.
There's plenty of disagreement in academia and in climate science. It's silly to say otherwise. The disagreement doesn't extend to any arbitrary argument regardless of merit; the debate isn't between "global warming is valid science" and "no it isn't" like it mostly does here*. There are scientists who believe that the climate change is not anthropogenic without losing the respect of their peers, but they don't publish a paper demonstrating this because they can't demonstrate it yet.
The academic community works frighteningly like Slashdot - people shuffle round reinforcing each other's ideas like a giant echo chamber, until another meme takes hold and replaces the current favourite
It is frightening how people characterize the smörgåsbord of opinions on /. as mindless groupthink when it suits their purposes. Yet here you are, posting on /., contributing your contrary opinion. So there goes that. In academia that's even less accurate since you act like these "memes" are just made up on the spot and that things like evidence never matter at all. Sure things are made up in random slashdot
I have to wonder though - wouldn't the oil companies know that their propaganda artists are the same ones who failed the tobacco lobby?
They failed eventually, but the scam worked for a long time and made their sponsors ridiculous piles of money. Far more than they ever stood to lose by having the truth come out. Sure they failed to keep the gravy train going forever, but that's still a damn good return on investment.
For the oil companies, this is perfect. They know the oil gravy train is going to stop eventually regardless, which is why they're already "energy" companies. They just need to muddy the waters long enough to maximize their profits. They'll still be in business after the oil runs out, but they'll be richer if they can keep the switch off fossil fuels from happening sooner than it has to.
No, they don't have to have a competing theory. They have to demonstrate that the anthropogenic global warming theory has axiomatic, logic, data or interpretation flaws sufficient to undermine findings, or that it is an unfalsifiable theory. That is sufficient to disregard the theory.
Not exactly, because any flaws in a theory should be weighed against the success of the theory before you decide whether to use it or not. We know for certain that both General Relativity and Quantum Mechanics have fundamental, axiomatic flaws. Like, neither works in the other's universe. Yet these are the two of the most successful theories of the 20th century, they're incredibly useful, and it would be foolish to disregard them simply because they contain logical flaws.
Science is always about having the best theory to explain observations, fully understanding that it is most likely flawed or incomplete or outright wrong. But for a theory to last long enough to be called a "theory" in scientific circles, there's enough evidence for it that it is highly unlikely to be outright wrong.
I am not saying this is the case with AGW, just that you do NOT need a competing theory before you can disregard another.
You're right at least in the general sense that many hypothesis can be safely rejected with no alternative explanation needed. But when the theory does do a good job of explaining observations, you pretty much do need to suggest an alternative that explains the data at least as well before the existing theory will be abandoned.
AGW does have a lot of evidence to support it. That doesn't make it the bona fide truth, it makes it a pretty good model. There are certainly flaws in the models and the data, but that's what models are for: making predictions despite being imperfect. Alternate theories, like it being due to volcanoes and solar radiance, which for anyone playing at home were thought of and accounted for long before you'd heard of the ideas, don't explain the data as well. So if you're doing real science, you'll probably find yourself having to come up with a better model of your own before you could seriously say that AGW shouldn't be the preferred theory. That was the GP's point, I think.
No one goes into the field expecting to make a lot of money.
Yeah, I always find it hilarious when people suggest money as the motivation for climatologists. Oh sure there's lots of politicking that goes on over acquiring grant money, but that's just the money you need to do your research. If there was nothing to research, why would you care about the grant money? It's not like you can use it to buy a Porsche. If you just wanted to do neat but useless stuff on someone else's dime, you'd study something DARPA cared about.
Which is more likely: that scientists got together and colluded to invent a crisis thinking it would make tons of money roll in, or that the wealthy are projecting their greed onto the less greedy? Occam's razor.
Well, Occam's Razor is about refraining from needlessly multiplying entities. Environmental scientists, being nerds, are much less likely to get laid than the MBAs running the fossil fuel industry. Ergo, the science conspiracy theory involves the least multiplying entities. The scientists did it, QED!
The security around the anthrax at that time wasn't what anyone would call 'high'.
Or alternatively they were and this was the problem. ;)
I guess I can understand that. Best to keep it simple, what with dealing with someone who thinks that the codeine in T3 would mask the pain from an APAP overdose.
There was codeine in Terminator 3?
Wow, you're right, that stuff is useless. It didn't do a thing to relieve the pain of watching that movie!
Most people don't need to defend their rights because most people are smart enough to just do what the man with the gun and the arrest powers says.
Most people don't need to defend their rights because they're smart enough to just let their rights be violated without complaint.
Is that seriously what you're trying to say?
Yeah, of course you don't need to defend your rights if you don't care about them. But what kind of fucked up solution is that?
What, you think game disks are analog?
They used to be. And I can say from personal experience that analog games had a warmth that modern digital games lack, though you really needed to get gold-plated controller connectors to really appreciate it.
If you were going to be flamed for anything, it should be for thinking I was trolling UoP graduates and replying with a lengthy rant that amounts to "Yes they're a for-pay diploma mill, but I managed to receive an education there in spite of this fact."
Which is awesome for you, but what I want to know is can I still get my PhD without the education? I just want the piece of paper to stave off alzheimers. :)
A study about reading, cards, and crosswords doesn't tell us anything about these games.
Sure it does.
The second link is about the effect of physical exercise on congitive decline.
Keep reading. ;)
On average, PhD.s have much healthier brains than most people, even in their 90s or older.
Well, that settles it. I'm off to buy my PhD from the University of Phoenix. I can't wait until I can hang my diploma on the wall and bask in it's brain-preserving rays. ;)
"Well you've shown that the game doesn't do X, but I feel that it might provide some other benefit" doesn't mean anything unless it's backed up with a study that shows that the game provides that other benefit.
Which is why in the second half of their post, which you appear to not have reached before making your interesting post, they provided links. :)
Christian actually means "Christ like". If you do not behave in a way that is similar to what he said to behave, you are not really Christian.
Which, ironically, would mean that anyone who would ostensibly like to call themselves a Christian must simultaneously admit that no actual Christians exist, especially not themselves.
Yeah, I thought that was the reason they banned porn apps from the App Store, as explained here.
"You know Steve, he's all about user interface. We considered changing the App Store so that when you enter 'boobs' it says, 'The web is that way, stupid!'"
Not necessarily. On some of the SPARC machines, it's relatively cheap, because there's a separate set of registers for each protection level.
On a typical system call you really only need to save the registers you use just like in a normal function call so it's relatively cheap in x86 too. Though it's hardly instantaneous to change privilege levels. I can certainly believe you when you say SPARC does this faster. But that's not what we're talking about.
We're talking about changing the Page Table Base Register (not sure if that's SPARC parlance, in x86 it's CR3 :P) to point at a different set of page tables. Doing that is damaging for performance in just about any virtual memory architecture, since it usually means flushing the TLB and stalling until all previous memory ops have completed to change PTBR values. You can partially mitigate it by tagging TLB entries with address space IDs, but you introduce a lot of complexity when you have to consider multiple translations to the same address in the TLB at the same time. Doubly so if you try to eliminate the stalls and rename the PTBR.
So regardless of how fast your privilege level switches are, it makes sense to have the OS mapped into the application's page table so you don't have to change address spaces.
I strongly disagree.
With the entire industry. It's okay. You're not the only one to have maintained the belief that segments are not useless crap. ;)
Segmented addressing got a bad name from the days of real mode
That wasn't "segmentation" in the academic sense, and it's the academic sense of segmentation, what is actually implemented in 32-bit protected mode, that has the well-deserved bad reputation among the engineers implementing and coding for it. Since the default in 32-bit mode was to effectively eliminate segmentation, it only made sense to just get rid of it.
That's not really hard to handle, especially since the code/data part is automatically handled by the processor.
In the sense that you don't have to specify that your code accesses use the code segment and data accesses use the data segment by default. However you still have to explicitly change code and data descriptors when changing between OS and user land and those operations are also not performance-neutral. They are rather slow in fact. Not as bad as a CR3 switch, but bad enough you don't want to do two (per segment, so four) just so the kernel can return the value in it's time_t structure.
And that's before adding on the performance penalty of having to do an extra addition for every access when not using zero-base segments. You realize how many man-years of performance widgets you've undone by doing that? :)
Kernel code would have to explicitly distinguish between user mode access and kernel mode access (which IMHO is good).
In theory, but the exact case in question (mmap) is one where you want the both kernel and application to have the fastest access to the mmap()ed region possible. Which, in case you were wondering, means you can't just map two linear addresses to the same physical page, one for the user and one for the kernel, because that results in TLB thrashing. And when you take that and then add all the other cases where the kernel needs to regularly access something that might be mapped in user land, and suddenly you've just recreated the need for far pointers, and passing around far pointers results in the same possibility for badly formed pointers as before. Remember, if making sure all your pointers were valid was easy we wouldn't have this problem in the first place.
There's a reason why even when IA32 provided these segmentation facilities that nobody used them. And it's not prejudice from the 16-bit days, as if that could explain why nobody else has implemented segmentation.
Good riddance to bad rubbish I say. Modern ISAs ftw, even if they're still CISCy. :)
If you can make the kernel read data from a NULL pointer you would be able to trick the kernel into reading a fake struct that you placed at NULL.
A pointer (that's NULL) pointing to a function, a pointer (that's NULL) pointing to a pointer to a pointer... It's all just pointer-chasing indirect function calls to me. :)
The mmap_min_addr checks were added to harden against the EXACT class of common bugs he describes and I'm saddened it was dismissed so out of hand.
Who dismissed it? The distros? The kernel devs?
Exception handling is immaterial anyway. It's not like you need language support for exceptions to check the value of an untrusted pointer against the NULL constant.
Yeah but constantly checking sucks, as does recovery.
Personally I use the method described by the uh... GGP? The dude what I first replied to. Basically, I refrain from using root access to tell the OS to let me map page 0, and then refrain from mmap()ing page 0. Then I let the hardware detect the illegal access for me. =D
But then it is not an exploit, since the kernel always is root anyway.
As given, no the procedure is not a working exploit for any meaningful definition ("I'm teh 1337 hacks-zor! I r00ted my home desktop!")
However, if you could identify a case where the kernel dereferenced a NULL function pointer, and if you could get around the kernel's mmap() protection (neither implausible), then you can get the kernel to run your code using its privilege level. Meaning you can get root for yourself. And then yes indeedy you have an exploit.