Ubuntu 32bit 4GB memory problems and solutions

The new upgrade system memory, from the original 2G to 4G, but when using the command view only see 3291M, as follows:

$ free-m Total used free shared buffers cached mem:3291 801 2489 0 342-/+ buffers/cache:363 2927 swap:1906 0 1906

Check it out to know that the default 32bit Linux system can only recognize 3291 (3G) memory, so if you want to use more than 3G of memory on 32-bit systems, you need to install Physical address Extension (PAE), The specific steps on Ubuntu are as follows:

$ sudo apt-get update $ sudo sudo apt-get install linux-headers-server linux-image-server linux-server $ sudo reboot

After restarting the system, view the memory condition

$ free-m Total used free shared buffers cached mem:3862 3732 129 0 127 1149-/+ buffers/cache:2455 1406 swap:5720 170 5550