10.4.7. Is Your RAM Not Being Recognized?

⁠10.4.7. Is Your RAM Not Being Recognized?

Only showing 3.5GB?

If you have 4GB or more memory installed, but Fedora only shows around 3.5GB or 3.7GB, you have probably installed a 32bit version of Fedora on a 64bit kernel. For modern systems, the 64bit version of Fedora is recommended. Refer to Section 2.1.2, “Which Architecture Is My Computer?” for more details.

Sometimes, the kernel does not recognize all of your memory (RAM). The following procedure will allow you to confirm this and then adjust the kernel if necessary.

Run the cat /proc/meminfo command and verify that the displayed quantity is the same as the known amount of RAM in your system. If they are not equal, you can first make a temporary change to confirm whether editing the kernel will be effective.
Reboot, and once you have loaded the GRUB boot screen, type e for edit.
You are presented with a list of items in the configuration file for the boot label you have selected. Move to the line that starts with linux or linuxefi.
At the end of the kernel line, add
```
mem=xxM
```
where xx equals the amount of RAM in your system in megabytes, then press F10 to boot the system.
Run cat /proc/meminfo again. If the known amount of RAM in your system is now displayed, add the following to the GRUB_CMDLINE_LINUX line in /etc/default/grub, inside the quotes, to make the change permanent:
```
mem=xxM
```
Replace xx with the amount of RAM you have in megabytes.

To update the grub.cfg file so that the change will take effect, run the following command with root privileges.

    # for BIOS systems
    grub2-mkconfig --output=/boot/grub2/grub.cfg

    # for UEFI systems
    grub2-mkconfig --output=/boot/efi/EFI/fedora/grub.cfg

The resulting grub menu entry might look like this:

     menuentry 'Fedora (3.16.0-0.rc2.git2.1.fc21.x86_64) 21 (Rawhide)' {
      load_video
      set gfxpayload=keep
      insmod gzio
      insmod part_gpt
      insmod ext2
      set root='hd1,gpt2'
      if [ x$feature_platform_search_hint = xy ]; then
        search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2  b34a57d9-03d7-415f-94f6-91689404d951
      else
        search --no-floppy --fs-uuid --set=root b34a57d9-03d7-415f-94f6-91689404d951
      fi
      linuxefi /vmlinuz-3.16.0-0.rc2.git2.1.fc21.x86_64 root=UUID=ece86abc-6419-4f29-84b6-1b810128f98d ro rootflags=subvol=root vconsole.font=latarcyrheb-sun16  vconsole.keymap=us LANG=en_US.UTF-8 mem=8192M
      initrdefi /initramfs-3.16.0-0.rc2.git2.1.fc21.x86_64.img
    }