2 GB limit
The 2 GB limit refers to a physical memory barrier for a process running on a 32-bit operating system, which can only use a maximum of 2 GB of memory. The problem mainly affects 32-bit versions of operating systems like Microsoft Windows and Linux, although some variants of the latter can overcome this barrier. It is also found in servers like FTP servers or embedded systems like Xbox. The use of Physical Address Extension (PAE) can help overcome this barrier.[clarification needed]
While Linux, FreeBSD, and most Unix-Likes support PAE so long as the hardware does, Windows needs this boot option enabled manually. This is known as 4-gigabyte tuning (4GT), or the /3GB switch. Once enabled, executables can have the "large address aware" flag set to increase their memory limit to 3GB. 32-bit processes on 64-bit Windows are also limited to 2GB. However, they can use the "large address aware" flag as well, except that it doesn't require the /3GB switch and increases the limit to 4GB.
- Richardson, Mike (24 July 2014). "Overcoming the Windows 2GB Caching Limit". O'Reilly Media. Retrieved 2015-08-18.
- "2.3.23-pre4 x86 64 GB RAM changes [HIGHMEM patch] explained a bit". 10 October 1999. Retrieved 2017-09-17.
- "Chapter 4. Hardware Compatibility". Retrieved 2017-09-17.
- "Memory Limits for Windows and Windows Server Releases". Microsoft. Retrieved 2017-09-17.
- "Maximum partition size using the FAT16 file system in Windows XP". Microsoft. Retrieved 2015-08-18.
- Large file support (LFS)
- File size
- File system
- Comparison of file systems: Limits
- 640 KB barrier
- 3 GB barrier
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