Mostly Fixed
I'm using a ThinkPad X240, and most linux distros report my total RAM as 3.8 GiB, but Ubuntu 15.10 is reporting 2.6 GiB.
I'm running 64-bit Ubuntu. I've checked my BIOS, and it says I have 4096 MB. I've tried running the live USB again, and it reports 3.8 GiB. I've tried reinstalling (without messing with my files) but it still shows 2.6 GiB.
Output of dmesg | grep "Memory: "
[ 0.000000] Memory: 2693004K/2856836K available (8146K kernel code,
1237K rwdata, 3800K rodata,1460K init, 1292K bss, 163832K reserved,
0K cma-reserved)
Output of dmidecode --type memory | grep -E "(Size|Maximum.Capacity)"
Maximum Capacity: 8 GB
Size: 4096 MB
Output of sudo lshw -short -C memory
H/W path Device Class Description
====================================================
/0/0 memory 2663MiB System memory
Output of free -m
total used free shared buffers cached
Mem: 2663 2641 21 261 7 1413
-/+ buffers/cache: 1220 1442
Swap: 7812 140 7671
That seems to indicate that a lot is being used for -/+ buffers/cache - though I might be misreading it. Could that be the issue? If so, then why does the system seem to need so much more than every other distro I've used on this laptop?
Output of uname -a
Linux chris-ThinkPad-X240 4.2.0-16-generic #19-Ubuntu SMP Thu Oct 8
15:35:06 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
I would really appreciate some help figuring out what's going on.
edit 1
Output of lspci
00:00.0 Host bridge: Intel Corporation Haswell-ULT DRAM Controller (rev 09)
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 09)
00:03.0 Audio device: Intel Corporation Haswell-ULT HD Audio Controller (rev 09)
00:14.0 USB controller: Intel Corporation 8 Series USB xHCI HC (rev 04)
00:16.0 Communication controller: Intel Corporation 8 Series HECI #0 (rev 04)
00:19.0 Ethernet controller: Intel Corporation Ethernet Connection I218-LM (rev 04)
00:1b.0 Audio device: Intel Corporation 8 Series HD Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 6 (rev e4)
00:1c.1 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 3 (rev e4)
00:1d.0 USB controller: Intel Corporation 8 Series USB EHCI #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation 8 Series LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 8 Series SATA Controller 1 [AHCI mode] (rev 04)
00:1f.3 SMBus: Intel Corporation 8 Series SMBus Controller (rev 04)
02:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5227 PCI Express Card Reader (rev 01)
03:00.0 Network controller: Intel Corporation Wireless 7260 (rev 83)
edit 2
Picture of my screen during memtest
edit 3 - Partial fix
OK, since there was nothing wrong with the hardware, and the RAM was definitely in it's place and undamaged, I decided it must have been an issue with the BIOS. So I downloaded the latest update from the Lenovo website, burnt a CD, and installed the update. Now I have 3.6 GiB of ram available, instead of 2.6. Still missing about 200 MiB of RAM, but it's definitely a step in the right direction. Also now the system at least recognises the total amount of RAM available.
Output of dmesg | grep "Memory: "
[ 0.000000] Memory: 3696432K/3874608K available (8146K kernel code,
1237K rwdata, 3800K rodata, 1460K init, 1292K bss, 178176K reserved, 0K
cma-reserved)
Output of sudo lshw -short -C memory
H/W path Device Class Description
=====================================================
/0/0 memory 3643MiB System memory
Any ideas about how to recover the 200 MiB of RAM that's still missing?