Effective RAM size not recognized

[Stephan1864]

Try adding this to your boot iommu=memaper=3

[manolomanolo]

Try adding this to your boot iommu=memaper=3

This is my /boot/grub/grub.cfg

Where do you think I should add those lines?
Thanks.

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
  set have_grubenv=true
  load_env
fi
set default="0"
if [ "${prev_saved_entry}" ]; then
  set saved_entry="${prev_saved_entry}"
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z "${boot_once}" ]; then
    saved_entry="${chosen}"
    save_env saved_entry
  fi
}

function recordfail {
  set recordfail=1
  if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}

function load_video {
  insmod vbe
  insmod vga
  insmod video_bochs
  insmod video_cirrus
}

insmod part_msdos
insmod ext2
set root='(hd0,msdos2)'
search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
if loadfont /usr/share/grub/unicode.pf2 ; then
  set gfxmode=auto
  load_video
  insmod gfxterm
  insmod part_msdos
  insmod ext2
  set root='(hd0,msdos2)'
  search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
  set locale_dir=($root)/boot/grub/locale
  set lang=it_IT
  insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ]; then
  set timeout=-1
else
  set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
insmod part_msdos
insmod ext2
set root='(hd0,msdos2)'
search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
insmod png
if background_image /usr/share/images/desktop-base/spacefun-grub.png; then
  set color_normal=light-gray/black
  set color_highlight=white/black
else
  set menu_color_normal=white/black
  set menu_color_highlight=black/light-gray
  if background_color 0,71,115; then
    clear
  fi
fi
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
if [ ${recordfail} != 1 ]; then
  if [ -e ${prefix}/gfxblacklist.txt ]; then
    if hwmatch ${prefix}/gfxblacklist.txt 3; then
      if [ ${match} = 0 ]; then
        set linux_gfx_mode=keep
      else
        set linux_gfx_mode=text
      fi
    else
      set linux_gfx_mode=text
    fi
  else
    set linux_gfx_mode=keep
  fi
else
  set linux_gfx_mode=text
fi
export linux_gfx_mode
if [ "$linux_gfx_mode" != "text" ]; then load_video; fi
menuentry 'Ubuntu, con Linux 3.0.0-14-generic-pae' --class ubuntu --class gnu-linux --class gnu --class os {
	recordfail
	set gfxpayload=$linux_gfx_mode
	insmod gzio
	insmod part_msdos
	insmod ext2
	set root='(hd0,msdos2)'
	search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
	linux	/boot/vmlinuz-3.0.0-14-generic-pae root=UUID=243dc9f9-1d3b-4042-8d5e-bee7480a9e11 ro splash acpi_osi=Linux  quiet splash vt.handoff=7
	initrd	/boot/initrd.img-3.0.0-14-generic-pae
}
menuentry 'Ubuntu, con Linux 3.0.0-14-generic-pae (modalità ripristino)' --class ubuntu --class gnu-linux --class gnu --class os {
	recordfail
	insmod gzio
	insmod part_msdos
	insmod ext2
	set root='(hd0,msdos2)'
	search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
	echo	'Caricamento Linux 3.0.0-14-generic-pae...'
	linux	/boot/vmlinuz-3.0.0-14-generic-pae root=UUID=243dc9f9-1d3b-4042-8d5e-bee7480a9e11 ro recovery nomodeset splash acpi_osi=Linux
	echo	'Caricamento ramdisk iniziale...'
	initrd	/boot/initrd.img-3.0.0-14-generic-pae
}
submenu "Previous Linux versions" {
menuentry 'Ubuntu, con Linux 3.0.0-14-generic' --class ubuntu --class gnu-linux --class gnu --class os {
	recordfail
	set gfxpayload=$linux_gfx_mode
	insmod gzio
	insmod part_msdos
	insmod ext2
	set root='(hd0,msdos2)'
	search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
	linux	/boot/vmlinuz-3.0.0-14-generic root=UUID=243dc9f9-1d3b-4042-8d5e-bee7480a9e11 ro splash acpi_osi=Linux  quiet splash vt.handoff=7
	initrd	/boot/initrd.img-3.0.0-14-generic
}
menuentry 'Ubuntu, con Linux 3.0.0-14-generic (modalità ripristino)' --class ubuntu --class gnu-linux --class gnu --class os {
	recordfail
	insmod gzio
	insmod part_msdos
	insmod ext2
	set root='(hd0,msdos2)'
	search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
	echo	'Caricamento Linux 3.0.0-14-generic...'
	linux	/boot/vmlinuz-3.0.0-14-generic root=UUID=243dc9f9-1d3b-4042-8d5e-bee7480a9e11 ro recovery nomodeset splash acpi_osi=Linux
	echo	'Caricamento ramdisk iniziale...'
	initrd	/boot/initrd.img-3.0.0-14-generic
}
menuentry 'Ubuntu, con Linux 3.0.0-13-generic' --class ubuntu --class gnu-linux --class gnu --class os {
	recordfail
	set gfxpayload=$linux_gfx_mode
	insmod gzio
	insmod part_msdos
	insmod ext2
	set root='(hd0,msdos2)'
	search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
	linux	/boot/vmlinuz-3.0.0-13-generic root=UUID=243dc9f9-1d3b-4042-8d5e-bee7480a9e11 ro splash acpi_osi=Linux  quiet splash vt.handoff=7
	initrd	/boot/initrd.img-3.0.0-13-generic
}
menuentry 'Ubuntu, con Linux 3.0.0-13-generic (modalità ripristino)' --class ubuntu --class gnu-linux --class gnu --class os {
	recordfail
	insmod gzio
	insmod part_msdos
	insmod ext2
	set root='(hd0,msdos2)'
	search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
	echo	'Caricamento Linux 3.0.0-13-generic...'
	linux	/boot/vmlinuz-3.0.0-13-generic root=UUID=243dc9f9-1d3b-4042-8d5e-bee7480a9e11 ro recovery nomodeset splash acpi_osi=Linux
	echo	'Caricamento ramdisk iniziale...'
	initrd	/boot/initrd.img-3.0.0-13-generic
}
menuentry 'Ubuntu, con Linux 3.0.0-12-generic' --class ubuntu --class gnu-linux --class gnu --class os {
	recordfail
	set gfxpayload=$linux_gfx_mode
	insmod gzio
	insmod part_msdos
	insmod ext2
	set root='(hd0,msdos2)'
	search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
	linux	/boot/vmlinuz-3.0.0-12-generic root=UUID=243dc9f9-1d3b-4042-8d5e-bee7480a9e11 ro splash acpi_osi=Linux  quiet splash vt.handoff=7
	initrd	/boot/initrd.img-3.0.0-12-generic
}
menuentry 'Ubuntu, con Linux 3.0.0-12-generic (modalità ripristino)' --class ubuntu --class gnu-linux --class gnu --class os {
	recordfail
	insmod gzio
	insmod part_msdos
	insmod ext2
	set root='(hd0,msdos2)'
	search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
	echo	'Caricamento Linux 3.0.0-12-generic...'
	linux	/boot/vmlinuz-3.0.0-12-generic root=UUID=243dc9f9-1d3b-4042-8d5e-bee7480a9e11 ro recovery nomodeset splash acpi_osi=Linux
	echo	'Caricamento ramdisk iniziale...'
	initrd	/boot/initrd.img-3.0.0-12-generic
}
}
### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry "Memory test (memtest86+)" {
	insmod part_msdos
	insmod ext2
	set root='(hd0,msdos2)'
	search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
	linux16	/boot/memtest86+.bin
}
menuentry "Memory test (memtest86+, serial console 115200)" {
	insmod part_msdos
	insmod ext2
	set root='(hd0,msdos2)'
	search --no-floppy --fs-uuid --set=root 243dc9f9-1d3b-4042-8d5e-bee7480a9e11
	linux16	/boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
if [ "x${timeout}" != "x-1" ]; then
  if keystatus; then
    if keystatus --shift; then
      set timeout=-1
    else
      set timeout=0
    fi
  else
    if sleep --interruptible 3 ; then
      set timeout=0
    fi
  fi
fi
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f  $prefix/custom.cfg ]; then
  source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###

[MoreOrLess]

/etc/default/grub
Add it to the GRUB_CMDLINE_LINUX_DEFAULT string

[manolomanolo]

/etc/default/grub
Add it to the GRUB_CMDLINE_LINUX_DEFAULT string

I added that line, but again all those tools go on telling me I just have about 3GB of RAM.

What can I do?
Thanks.
Regards.

[MoreOrLess]

I forgot to tell you to run update-initramfs after editing (and then reboot) :\

sudo update-initramfs -u -k all

[manolomanolo]

up.

I still suffer the same problem.
Many linux kernels updates have been passed on my installation from then on.
I still cannot understand why I can only use part of my RAM.

Do you have any clue?
Thanks.
Regards.

[prodigy_]

Why don't you just install a 64-bit OS? This wouid certainly solve the problem.

[N00b-un-2]

I know that you said your computer supports up to 8GB of RAM, but are you absolutely sure about that? I am on an IBM Thinkpad T60 right now which has 4GB of RAM installed in it. It has an i915 chipset and therefor will only address 3GB of the 4GB I have installed.

[prodigy_]

IBM Thinkpad T60 right now which has 4GB of RAM installed in it. It has an i915 chipset and therefor will only address 3GB of the 4GB I have installed.

The OP's laptop is based on Pentium T3x00, so it supports 64-bit.

[N00b-un-2]

You are not listening to what I'm saying. I HAVE A CORE 2 DUO. My computer is 64 bit as well. I am running Windows 8 Pro 64 bit, Ubuntu 12.10 64 bit and Mac OS X 10.6.8 which is ALSO 64 bit. The limitation is not an architecture limitation (the 32 bit 3GB RAM ceiling). The issue is the north/south bridge controller chipset. It is a hardware limitation of the chipset of my motherboard that ANY operating system, regardless of whether i386 or x86_64 will ONLY be able to utilize 3GB of RAM. PERIOD.

What I am suggesting is that perhaps the OP's computer has a similar hardware limitation. OP stated that his computer supports up to 8GB of memory, but given that it refuses to allocate the full amount of installed memory even using the PAE kernel, it's quite possible that this is hardware limitation like mine.