Linked by Thom Holwerda on Wed 5th Jan 2011 22:09 UTC
Windows And this is part two of the story: Microsoft has just confirmed the next version of Windows NT (referring to it as NT for clarity's sake) will be available for ARM - or more specifically, SoCs from NVIDIA, Qualcomm, and Texas Instruments. Also announced today at CES is Microsoft Office for ARM. Both Windows NT and Microsoft Office were shown running on ARM during a press conference for the fact at CES in Las Vegas.
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RE[4]: enough bits?
by oiaohm on Fri 7th Jan 2011 12:10 UTC in reply to "RE[3]: enough bits?"
oiaohm
Member since:
2009-05-30

"Also important note the 4GB limit on 32 bit OS on a lot of x86 chips is garbage as well. PAE mode. 64gb to 128gb. 32 bit mode.

So 32 bit being limited to 4GB is mostly a market bending nothing more by Microsoft.


PAE allows the *kernel* to access more than 4 GB of RAM. However, *processes* can only see 4 GB of RAM, period. Each process can be given it's own 4 GB chunk of memory, though. But they are still limited to 4 GB.

And the kernel has to do a lot of thunking and bounce buffers and hoop jumping and whatnot to manage PAE accesses. And all your drivers need to be coded to support PAE. And all your low-level apps need to be coded to support PAE. And on and on.
"
Really name a Linux program that has to be changed between PAE mode and non PAE mode. Answer zero.

PAE does not have to have anything todo with userspace.

PAE thunking is way lighter than swapspace.

What stunts do 32 bit programs that need to use more than 4gb of space use. Memory mapping to file. PAE Provides more access to storage space so can reduce number of disk operations on a memory mapped file.

So don't quote trash. 64 bit system is not the only way to exceed the 4 GB limit.

Yes a program running on a Non PAE 32 bit machine can be using methods already to have more space than the 4 gb limit at the cost of performance. PAE enables you to reduce the cost of those stunts.

Shock horror is just using PAE for swap, disk cache and assisting mapped files to reduce disk accesses don't require you to be running all PAE compatible drivers. Since most drivers should not be messing with this stuff.

Here is the best bit of all PAE used this way is not even new. Its basically using same style as Expanded memory. Yes breaking the 4 gb limit goes back to 1984.

The limit is 4 gb of memory at 1 time on x86 32 bit. Yes memory mapping and other methods means a program could be many times large than that in reality with or without PAE active.

Difference is PAE can remove the speed hits from the methods used by programs to exceed the 4gb limit.

That is the big mistake here. You are presuming that programs will not be using more than 4gb of memory. That presume is based on the idea that the OS did not provide programmers with a way around that problem. What is incorrect.

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