It Looks Like Systemd 231 Will Soon Be Released, Adds MemoryDenyWriteExecute

[starshipeleven]

Those Semprons are 32bit Thoroughbreds dumbass. Those ones arent 64bit..

My point is still valid duh.
most AMD stuff in 2004 did not have EVP/NX, just as Intel.
First stuff with NX/EVP appeared during 2004 on both camps.
By 2005 every processor had NX/EVP and most also had 64bit.

[duby229]

My point is still valid duh.
most AMD stuff in 2004 did not have EVP/NX, just as Intel.
First stuff with NX/EVP appeared during 2004 on both camps.
By 2005 every processor had NX/EVP and most also had 64bit.

No you don't have a point. Here's what is screwed up, -all- 64bit AMD processors have the bit, but -not all- 64bit Intel processors do.

https://en.wikipedia.org/wiki/NX_bit

After AMD's decision to include this functionality in its AMD64 instruction set, Intel implemented the similar XD bit feature in x86 processors beginning with the Pentium 4 processors based on later iterations of the Prescott core

EDIT: And that was a tiny subset of what they released. It wasn't until 2007 with the launch of Conroe that Intel finally resolved that compatibility issue along with several others. EM64T was -not- fully compatible with AMD64 and the NX bit was only one piece of that.

[R00KIE]

No, you don't need PAE if you have 4 GB of RAM. PAE is useful only for 4-64 GB. If you have exactly 4 GB and a 64-bit capable CPU, the options are (from best to worst): x32, x86 (no PAE), x86 (PAE), x86-64. Also you could have a 64-bit kernel and a 100% 32-bit user space. There are plenty of options, it's not just black and white.

You are the one who suggested that people with 6GB or less could run 32bit just fine, last time I checked 6GB is still more than 4GB. Not to mention you can't make use of the full 4GB because you need to have enough address space to access all the hardware in your machine, so you probably get a bit over 3GB of usable ram.

[starshipeleven]

No you don't have a point. Here's what is screwed up, -all- 64bit AMD processors have the bit, but -not all- 64bit Intel processors do.

Yeah, it's totally screwed up. Because it's not true at all.
Find me here http://ark.intel.com/products/family...Processor#@All and here http://ark.intel.com/products/family...20celeron#@All
any Intel processor with 64bits and no NX

You can say that not all Intel processors of that time had NX and it would have been true, but all those were 32bits. Intel even had some 32bit processors with NX (the ones with J at the end of the name), while AMD decided to go full 64bit on all processors, so you're hallucinating again.

[duby229]

Yeah, it's totally screwed up. Because it's not true at all.
Find me here http://ark.intel.com/products/family...Processor#@All and here http://ark.intel.com/products/family...20celeron#@All
any Intel processor with 64bits and no NX

You can say that not all Intel processors of that time had NX and it would have been true, but all those were 32bits. Intel even had some 32bit processors with NX (the ones with J at the end of the name), while AMD decided to go full 64bit on all processors, so you're hallucinating again.

Duh... Only some of the Prescotts were 64bits, those that were was a small portion of the total and that wasn't fixed until 2007 with the launch of Conroe. You say it's not true in your first sentence and then say exactly the same thing I did with proofs in the links. Why do you say the same thing I did and then ask me to repeat myself?

EDIT: And that was only part of the problem, EM64T was not fully compatible with AMD64 until Conroe. It was not worth using a 64bit OS on any Intel product Until then. I doubt very highly you're old enough to remember Prescott. A highly expensive, buggy, incompatible, slow as hell, space heater.

[F.Ultra]

64 bit apps use more RAM on Linux. It's a fact. The pointers, alignment all add to memory use. Normal C code that uses types like 'int' for normal variables also doubles in size. OTOH, x84-64 doesn't improve the density of the instruction set that much. So overall you lose RAM. It's easy to verify. Just download a live image of some distro with both 32 and 64 bit userland and compare.



On my 32b desktop with 4 GB of RAM, the command 'free' shows 3,7GB in total. It does use dedicated AGP graphics with its own RAM chips onboard. If I start up LXDE, the free RAM is around 3,5 GB.

Pointers are doubled yes, and aligment of 64-bit entities waste RAM if the programmer have not taken this into account but int's are still 32-bit due to Linux using the LP64 model, it's only long that are promoted from 32-bit to 64-bit between a 32-bit and 64-bit program. The amount of "waste" is quite small if the programmer accounts for the changes while the calculations can be quite faster due to the twice amount of registers that's available.

[caligula]

I never noticed any substantial difference in normal use.

Yeah, I've done that back then with my 2GB netbook and it was not noticeable. That's why I'm talking to you.

For what it's worth, I tried the latest Ubuntu Desktop 16.04.1 LTS both in a 64bit QEMU virtual machine and a 32bit QEMU machine. I started both with
qemu-system-x86_64 -m 4096 -cdrom path-to-isofile.iso -enable-kvm

Guess what, after starting the default desktop + firefox + libreoffice writer, the results are:
32-bit:
total 4042M
used 618M
available 2998M

64-bit
total 3951M
used 812M
available 2816M

My math tells me the userspace in the 64-bit distro uses 31% more RAM when doing these things. How is that not relevant when you only have tiny amounts of RAM? Starting the desktop and these two apps already consumed almost one third of the RAM.

[caligula]

Pointers are doubled yes, and aligment of 64-bit entities waste RAM if the programmer have not taken this into account but int's are still 32-bit due to Linux using the LP64 model, it's only long that are promoted from 32-bit to 64-bit between a 32-bit and 64-bit program. The amount of "waste" is quite small if the programmer accounts for the changes while the calculations can be quite faster due to the twice amount of registers that's available.

Guess what, that's purely theoretical. In practice, the apps use more RAM. I recommend downloading some live distro like Ubuntu and trying it out. The numbers might surprise you. I did some calculation in the previous post above ^

Also, I'm not really arguing about the perf benefits. It's clear that x86-64 provides more registers, wider registers, more instructions (especially SIMD), different memory model etc. They're not relevant if you are constrained by RAM like you usually are on a low end machine -- these days, even when just doing simple web browsing.

[DanL]

Only some of the Prescotts were 64bits, those that were was a small portion of the total and that wasn't fixed until 2007 with the launch of Conroe... And that was only part of the problem, EM64T was not fully compatible with AMD64 until Conroe..

Okay, but even if we accept that, why assume that Intel specifically chose to not support the NX bit in its initial 64-bit CPU's as a way to force people to upgrade? The systems out there with P4 hardware are probably still running XP/Vista or maybe upgraded to Win7. I really doubt a lot of people out there thought, "Darn! Now I have to go get a new system to run Win 8/10 because of the NX bit. Everything else is running great! This P4 and Geforce FX 5300 run wonderfully! Cursed Intel and their greed!"

You have to realize that Intel and AMD didn't sit down in a room together and develop x86-64, and that the technology was going to take some time to standardize, especially without a lot of mainstream users (XP-64 was a niche at best and Intel was focued on Itanium64/IA64 in server space).

[duby229]

Okay, but even if we accept that, why assume that Intel specifically chose to not support the NX bit in its initial 64-bit CPU's as a way to force people to upgrade? The systems out there with P4 hardware are probably still running XP/Vista or maybe upgraded to Win7. I really doubt a lot of people out there thought, "Damn! Now I have to go get a new system to run Win 8/10 because of the NX bit. Everything else is running great! This P4 and Geforce FX 5300 run wonderfully! Cursed Intel and their greed!"

You have to realize that Intel and AMD didn't sit down in a room together and develop x86-64, and that the technology was going to take some time to standardize, especially without a lot of mainstream users (XP-64 was a niche at best and Intel was focued on Itanium64/IA64 in server space).

Well, why wouldn't people blame them when those products didn't meet specs to a degree sufficient enough to function appropriately? It's the same reason people blame MS for their EEE tactics, they've used those tactics so many times before that we would all be stupid to pretend it won't happen again.