Added 2x DIMMs to Linux system but not seen in Total Memory

Sunday, March 3, 2019

I had an old PC with Arch Linux

$ uname -a
Linux desktop 4.1.4-1-ARCH #1 SMP PREEMPT Mon Aug 3 21:53:10 UTC 2015 i686 GNU/Linux

with 2GB RAM. I've added 2x1Gb DDR2 DIMMs and now the system has DIMMs in all banks (4x1GB). The new memory is detected in the BIOS:

System Memory Available  4024 MB

And also the output of lshw shows all the slots populated with 1GB DIMM

But the Total Memory in /proc/meminfo shows only 2GB:

$ grep MemTotal /proc/meminfo 

MemTotal:        2058968 kB

I've tried to edit the kernel params in GRUB and add mem=4G, but the total memory remains 2GB.

Any ideas what else to try?

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