I said with the advent of the x86 Macs that I would switch with my next computer. I saw no reason to stick with PCs besides price, and paying $200 or whatever for the ability to run OS X alongside Windows without dealing with cracks was reasonable to me.
However, Apple and Intel have let me down. I'm in the market for a new laptop. Apple claims that their laptops can run Windows, but that's not true. Apple has still not made a 2 button mouse, and good luck running Windows without right clicking. They have a 1.5 button mouse for desktops, but their laptops only have 1 mouse button. You can't replace the built-in mouse, either, unless you always use your laptop where you have a place for an external mouse.
Intel has let me down as well. I want 64 bit support in my next machine. The Core series does not support 64 bits, and it sucks. I have no idea how long I'd have to wait to get a Merom or whatever it's called.
Whenever Apple and Intel resolve these problems, I won't need to get PCs anymore.
On an embedded system, there is no particular reason that an object could not legitimately be at address 0. It is mostly by convention that nothing is placed at that address.
In DOS, the data at address 0 is either a pointer to the function called when there is an integer division by 0 or a pointer to machine instructions that mean "exit program".
Task switching between the monitor and the virtualized task is much more expensive than a user-kernel-user switch.
Melissa
Paranoia about IRCing as root
on
Explorer Destroyer
·
· Score: 2, Insightful
There's all this paranoia about IRCing as root, even servers that K-line root@*, but it's all pointless. Most people IRC as root, including me, because they run mIRC in Windows.
I don't see it any different than web browsing as root, and guess what, there has been far more exploits against M$IE than there have against mIRC. Or xchat.
Probably the easiest errata to come by is the instruction "CALL ESP" (or "CALL RSP"). On AMD CPUs, "CALL ESP" will jump to the address in ESP, *then* push the return address. However, on Intel CPUs, it will push the return address first, then jump to the value it just pushed. This is, of course, disasterous if you try to use it.
According to Intel errata documents, this is a bug in the Pentium Pro that has been kept for several generations. The Pentium and below, except the 8086 and 8088, worked correctly with this instruction.
If you want to differentiate Intel and AMD in your program and don't want to use CPUID, you can set up a test with CALL ESP.
I hope that you don't exclude people with grades lower than 3.0 outright. I got mediocre grades in college, yet I feel that I'm a better programmer than the people I work with at a game company. I've been programming since I was 9 years old or so, and am now very knowledgeable about low-level programming, especially x86 and Win32/Win64.
I feel that all I learned in college was formal names and definitions for the things I already knew. Necessary things, but stuff I wish I didn't have to waste 6 years to get when I probably would've picked it up in 1.
Firefox 1.5.0.2 fixed 3 bugs that allowed JavaScript code to cause buffer overflows and execute arbitrary machine code. It's not just Internet Exploder that has this problem.
Guitar Hero is a very close ripoff of Guitar Freaks from Konami, which came out back in the days of PlayStation 1. What is so special about this ripoff compared to the original?
How are you able to any of those sequence of operations if you are not *already* executing as root or as ring 0? If you already have control of ring 0 and/or root, you can do what you want to the computer already. SMM doesn't get you anything special, except perhaps the ability to mess with internal processor states you can't normally (make writable code segments in protected mode, for example).
By the way, whenever the CPU does a memory read or write while in SMM, it asserts the SMM# pin. This means that the hardware is fully able to consider SMM RAM to be totally separate from the main memory space - but most implementations don't. In fact, SMM has an instruction called "umov" that allows SMM hypervisors to read/write the main memory space. (umov is equivalent to mov when not in SMM.)
If it's *really* a problem, change the motherboard, not the CPU. The motherboard can physically lock out the SMM memory space from even kernel programs if it so desires.
Actually, the last byte can be any value from C8 to CF. The mnemonic for the F0 0F C7 C8 instruction would be "lock cmpxchg8b eax". Specifying any register as a parameter to cmpxchg8b is illegal, and it's the "lock" combined with the delayed illegal opcode exception that confuses the Pentium 1 into freezing. C8...CF specify that the parameter is one of the 8 main registers.
Windows NT has a similar "device", called \Device\PhysicalMemory. If you're an administrator you can access it through a bunch of API trickery (the documented Win32 API doesn't have the necessary functionality).
On a side note, \Device\PhysicalMemory isn't a "file" object as on Linux, it's a "section" object. Win32 programmers know this as the type of object returned from CreateFileMapping and OpenFileMapping. You can't read or write this "device" using the file API, but you can do MapViewOfFile(Ex) on it to map arbitrary physical pages into your process space.
When you allocate memory in Windows NT (2000/XP/2003/Vista) with NtAllocateVirtualMemory, it starts out all zero. To optimize this, the "System Idle Process" actually zeros out memory pages all the time, in the hopes that there will be enough pages available when an application wants them. It works out pretty well. If there aren't enough pages, NtAllocateVirtualMemory will block while it does a rep stosd / rep stosq.
In case you're wondering, when the kernel detects it's on battery power, the System Idle Process becomes an "hlt" loop to shut off the processor instead of a memory zeroing process. (Similarly, if there are no more pages to zero when on AC power, it also goes into an "hlt" loop.)
15 years ago, when I was 10, everyone hated Nintendo and how their stuff was overpriced, and how Sega was better. (Remember $75 for Mario 3?) Now it has turned around and everyone on Slashdot (then, BBS's) is praising Nintendo and badmouthing Sony.
All you have to do is make a back door that requires a 8192-bit RSA private key to use. Even if you knew it was there, you wouldn't be able to exploit it.
Even simpler, store a SHA-256 hash of some random very long (~30 chars) password. The back door would only work if someone gave the program that exact password, and brute forcing it would be essentially impossible.
Does anyone *really* think that there would be anything important in those documents? It's not like the location of Osams bin Laden or of Saddam's chemical weapons in Syria will be in these documents.
This particular arm of the government is not dumb enough to publicly release anything that has a remote chance of being important. After all, such documents likely show some of our wrongdoings too.
PSO had a good way of handling regions. There were servers that were located in each region (and they were clearly labeled). However, you could travel to them whenever you wanted.
This lets you stay with people that speak your language, while at the same time being able to go to other regions whenever you want to.
This is out of the question with World of Warcraft, because Blizzard has a huge interest in keeping them separate. The Chinese version is *much* cheaper than the American version, and American players would flock to the Chinese payment system the instant they could do that and still play with other Americans.
(There is also the problem of gold farming, but because so many people have a racist viewpoint on it I'm not going to bother discussing that.)
It can't be, at least not efficiently. Like flash devices, it's impossible to write less than a sector at a time.
If this were transparently implemented by the hardware, the OS would frequently try to write a single 512 byte sector. In order for this to work, the hard drive controller would have to read the existing sector then write it back with the 512 bytes changed. This is a big waste, as a read then a write costs at least a full platter rotation (1/7200 second). Do this hundreds or thousands of times per second, and you have a nice slow hard drive.
Slashdot Mirror
I said with the advent of the x86 Macs that I would switch with my next computer. I saw no reason to stick with PCs besides price, and paying $200 or whatever for the ability to run OS X alongside Windows without dealing with cracks was reasonable to me.
However, Apple and Intel have let me down. I'm in the market for a new laptop. Apple claims that their laptops can run Windows, but that's not true. Apple has still not made a 2 button mouse, and good luck running Windows without right clicking. They have a 1.5 button mouse for desktops, but their laptops only have 1 mouse button. You can't replace the built-in mouse, either, unless you always use your laptop where you have a place for an external mouse.
Intel has let me down as well. I want 64 bit support in my next machine. The Core series does not support 64 bits, and it sucks. I have no idea how long I'd have to wait to get a Merom or whatever it's called.
Whenever Apple and Intel resolve these problems, I won't need to get PCs anymore.
Melissa
Who would want to even pirate Madden 2036? Sure, warez collectors have everything, but most pirates tend to copy good games =)
Melissa
On an embedded system, there is no particular reason that an object could not legitimately be at address 0. It is mostly by convention that nothing is placed at that address.
In DOS, the data at address 0 is either a pointer to the function called when there is an integer division by 0 or a pointer to machine instructions that mean "exit program".
Melissa
In OS X, you access the resource fork by opening filename/rsrc with open() or whatever. In 10.4.x, you can have other files inside that file.
:. You can in fact copy Mac files as filename.txt:rsrc if you wanted.
In Windows NT on NTFS, it's similar, except rather than / it's
Melissa
Task switching between the monitor and the virtualized task is much more expensive than a user-kernel-user switch.
Melissa
There's all this paranoia about IRCing as root, even servers that K-line root@*, but it's all pointless. Most people IRC as root, including me, because they run mIRC in Windows.
I don't see it any different than web browsing as root, and guess what, there has been far more exploits against M$IE than there have against mIRC. Or xchat.
Melissa
Probably the easiest errata to come by is the instruction "CALL ESP" (or "CALL RSP"). On AMD CPUs, "CALL ESP" will jump to the address in ESP, *then* push the return address. However, on Intel CPUs, it will push the return address first, then jump to the value it just pushed. This is, of course, disasterous if you try to use it.
According to Intel errata documents, this is a bug in the Pentium Pro that has been kept for several generations. The Pentium and below, except the 8086 and 8088, worked correctly with this instruction.
If you want to differentiate Intel and AMD in your program and don't want to use CPUID, you can set up a test with CALL ESP.
Melissa
I hope that you don't exclude people with grades lower than 3.0 outright. I got mediocre grades in college, yet I feel that I'm a better programmer than the people I work with at a game company. I've been programming since I was 9 years old or so, and am now very knowledgeable about low-level programming, especially x86 and Win32/Win64.
I feel that all I learned in college was formal names and definitions for the things I already knew. Necessary things, but stuff I wish I didn't have to waste 6 years to get when I probably would've picked it up in 1.
Melissa
Firefox 1.5.0.2 fixed 3 bugs that allowed JavaScript code to cause buffer overflows and execute arbitrary machine code. It's not just Internet Exploder that has this problem.
No Execute and stack cookies FTW.
Melissa
The DOJ has a vested interest in saying that child pornography is on the rise. Don't trust them.
Melissa
Guitar Hero is a very close ripoff of Guitar Freaks from Konami, which came out back in the days of PlayStation 1. What is so special about this ripoff compared to the original?
Melissa
If someone proves that P != NP, it won't affect most of the world. There would not be much use for such a proof.
A proof that P == NP would change the computing world forever.
My bet's on P != NP, but I also believe that public-key cryptography is impossible (IE, that RSA and such will eventually be broken).
Melissa
How are you able to any of those sequence of operations if you are not *already* executing as root or as ring 0? If you already have control of ring 0 and/or root, you can do what you want to the computer already. SMM doesn't get you anything special, except perhaps the ability to mess with internal processor states you can't normally (make writable code segments in protected mode, for example).
By the way, whenever the CPU does a memory read or write while in SMM, it asserts the SMM# pin. This means that the hardware is fully able to consider SMM RAM to be totally separate from the main memory space - but most implementations don't. In fact, SMM has an instruction called "umov" that allows SMM hypervisors to read/write the main memory space. (umov is equivalent to mov when not in SMM.)
If it's *really* a problem, change the motherboard, not the CPU. The motherboard can physically lock out the SMM memory space from even kernel programs if it so desires.
Melissa
Maybe the quantization of the universe and its accompanying randomness are caused by floating point roundoff error in the god machine?
Melissa
Actually, the last byte can be any value from C8 to CF. The mnemonic for the F0 0F C7 C8 instruction would be "lock cmpxchg8b eax". Specifying any register as a parameter to cmpxchg8b is illegal, and it's the "lock" combined with the delayed illegal opcode exception that confuses the Pentium 1 into freezing. C8...CF specify that the parameter is one of the 8 main registers.
Melissa
Windows NT has a similar "device", called \Device\PhysicalMemory. If you're an administrator you can access it through a bunch of API trickery (the documented Win32 API doesn't have the necessary functionality).
On a side note, \Device\PhysicalMemory isn't a "file" object as on Linux, it's a "section" object. Win32 programmers know this as the type of object returned from CreateFileMapping and OpenFileMapping. You can't read or write this "device" using the file API, but you can do MapViewOfFile(Ex) on it to map arbitrary physical pages into your process space.
Melissa
When you allocate memory in Windows NT (2000/XP/2003/Vista) with NtAllocateVirtualMemory, it starts out all zero. To optimize this, the "System Idle Process" actually zeros out memory pages all the time, in the hopes that there will be enough pages available when an application wants them. It works out pretty well. If there aren't enough pages, NtAllocateVirtualMemory will block while it does a rep stosd / rep stosq.
In case you're wondering, when the kernel detects it's on battery power, the System Idle Process becomes an "hlt" loop to shut off the processor instead of a memory zeroing process. (Similarly, if there are no more pages to zero when on AC power, it also goes into an "hlt" loop.)
Melissa
15 years ago, when I was 10, everyone hated Nintendo and how their stuff was overpriced, and how Sega was better. (Remember $75 for Mario 3?) Now it has turned around and everyone on Slashdot (then, BBS's) is praising Nintendo and badmouthing Sony.
Melissa
Our President definitely can vote while in office. A president can even vote for themselves for reelection while in office.
They even show on TV when the President votes in a major election.
Melissa
All you have to do is make a back door that requires a 8192-bit RSA private key to use. Even if you knew it was there, you wouldn't be able to exploit it.
Even simpler, store a SHA-256 hash of some random very long (~30 chars) password. The back door would only work if someone gave the program that exact password, and brute forcing it would be essentially impossible.
Melissa
Does anyone *really* think that there would be anything important in those documents? It's not like the location of Osams bin Laden or of Saddam's chemical weapons in Syria will be in these documents.
This particular arm of the government is not dumb enough to publicly release anything that has a remote chance of being important. After all, such documents likely show some of our wrongdoings too.
Melissa
Can Amanda handle POSIX access control lists?
Melissa
PSO had a good way of handling regions. There were servers that were located in each region (and they were clearly labeled). However, you could travel to them whenever you wanted.
This lets you stay with people that speak your language, while at the same time being able to go to other regions whenever you want to.
This is out of the question with World of Warcraft, because Blizzard has a huge interest in keeping them separate. The Chinese version is *much* cheaper than the American version, and American players would flock to the Chinese payment system the instant they could do that and still play with other Americans.
(There is also the problem of gold farming, but because so many people have a racist viewpoint on it I'm not going to bother discussing that.)
Melissa
It can't be, at least not efficiently. Like flash devices, it's impossible to write less than a sector at a time.
If this were transparently implemented by the hardware, the OS would frequently try to write a single 512 byte sector. In order for this to work, the hard drive controller would have to read the existing sector then write it back with the 512 bytes changed. This is a big waste, as a read then a write costs at least a full platter rotation (1/7200 second). Do this hundreds or thousands of times per second, and you have a nice slow hard drive.
Melissa
Why not call it D flat?
Melissa