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[8]: enough bits?
by Neolander on Thu 6th Jan 2011 22:13 UTC in reply to "RE[7]: enough bits?"
Neolander
Member since:
2010-03-08

I can't understand how that swapping you describe could possibly work.

As we both know, ordinary swapping occurs when you run out of physical memory, but you still have some spare linear addresses around. In that case, all the kernel has to do is to allocate a new range of linear addresses and return a pointer to the beginning of it as usual, but mark the corresponding pages as absent.

Later on, when the process tries to access one of these newly allocated linear addresses, a page fault occurs. The kernel is summoned, and it swaps some things in and out so that the requested data ends up being in RAM. Then it makes the non-present linear addresses point there, marks them as present, and the process starts running again as if nothing happened.

But what we're talking about is totally different. It's when we are running out of linear addresses, but still have some spare physical addresses. The virtual address space of the application is now full, even though the RAM is not.

In that case, malloc() and such simply can't work anymore. Because there is no new pointer they could possibly use and return. All possible pointers of 32-bit addressing are already in use somewhere in the process. There is no such thing as a spare linear address range which we could mark as non-present as we do in swapping.

Edited 2011-01-06 22:25 UTC

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