64-bit OS version?

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xSkyFoXx2011-05-28 12:23:44

Operating Systems

xSkyFoXx, 2011-05-28 12:23:44

64-bit OS version?

Why do I have either under Linux (Ubuntu), or under Windows (7) if I install the 32-bit version of the OS, only 3 or 3.5 Gb of RAM are visible and active? Although a 32-bit OS seems to just provide support for exactly up to 4 gigs.

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5 answer(s)

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vinxru, 2011-05-28
@vinxru

Yashin correctly said that the address space is used not only by memory, but by all other devices.
It is often impossible in hardware to arrange the address spaces of all devices one after the other without unused gaps.
More than 4 GB on a 32-bit computer can be used. To do this, the motherboard, processor, operating system and all drivers must support PAE mode. This PAE mode allows you to use 64 GB of address space.
en.wikipedia.org/wiki/Pae

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Jock Tanner, 2011-05-28
@Tanner

32-bit OS versions (both Linux and Windows 7) support up to 64 GB address space, up to 3 GB per task.
Rebuild the Linux kernel with PAE support.
In 32-bit Windows, PAE is always enabled to allow the use of the entire address space, use the patch:
rutracker.org/forum/viewtopic.php?t=3301661
To understand the issue of memory addressing in x86, you can read this:
www.geoffchappell. com/viewer.htm?doc=notes/windows/license/memory.htm
Most importantly, do not believe those who talk about the 4 GB processor limit. PAE first appeared in the Intel Pentium Pro processor and is used by all modern operating systems.

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Roman, 2011-05-28
@WNeZRoS

If you have a laptop, then perhaps a part is taken by the video card for its needs. Ubuntu and Windows 7 (both x86) see 3.8 GB (out of 4 GB) for me, while the missing RAM is added to the video card memory.

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xSkyFoXx, 2011-05-28
@xSkyFoXx

No, the video card is still external. There are several computers, with different operating systems, and they are not all laptops.