All memory not working on Samsung R410-FB04 laptop in Kubuntu x64?

Question

linux

Good day to all! I have been using a Samsung R410 Plus laptop for a long time at home (model R410-FB04, T3200 processor, intel G45 chipset, integrated video), Kubuntu 12.04 x64 OS. Initially, the laptop had 2 GB of memory with one DDR2 stick, there were 2 slots in total, i.e. you can put a second bar. A year ago, I took up the issue - I bought another 2 GB, moved to the x64 distribution, but ran into a strange problem - at the kernel boot stage, the computer goes into reboot and so on ad infinitum. x86 live - the distribution works, but only sees 3 GB.
x64 distribution is loaded only if you limit the memory by specifying mem=4096m to the kernel , but again only 3GB is visible.
A year ago, I procrastinated the problem on the Kubuntu forum , but did not find a solution. And here the peopleDSDT problems in laptops are correct, I thought, maybe someone can help me! ;-)
In short, my research from the forum:
I found out that the problem is in the BIOS, and not in the memory - I tried a couple of identical Hynix sticks, now one is Samsung, the other is Kingston.
BIOS says 2x2 Gb of memory, lshw says the same:
lshw output *-memory
description: System Memory
physical id: e
slot: System board or motherboard
size: 4GiB
*-bank:0
description: SODIMM DDR2 Synchronous 667 MHz (1, 5 ns)
product: SODIMM000
vendor: Mfg 0
physical id: 0
serial: 1234-B0
slot: M1
size: 2GiB
width: 64 bits
clock: 667MHz (1.5ns)
*-bank:1
description: SODIMM DDR2 Synchronous 667 MHz (1.5 ns)
product: SODIMM001
vendor: Mfg 1
physical id: 1
serial: 1234-B1
slot: M2
size: 2GiB
width: 64 bits
clock: 667MHz (1.5ns)
While running memtest, I noticed a strange thing: first it checks up to 2048 MB, then up to 3046 MB, but further from 4096 to 5120 MB.
Those. the memory is somehow strangely addressed, if you set the “define memory yourself” parameter, then memtest hangs.
No memory-related settings were found in the BIOS. I specifically flashed the latest version - the problem was not solved. The G45
's memory controller supports up to 8 GB of memory.
By the way, Samsung itself supplied these models with a maximum of 3 GB of RAM.
Now the essence of the question is how to get around such a hardware crookedness? I see this solution: tell the kernel not to use a block of memory from 3046 MB to 4096, but how to do this?

Answer 1

I noticed a strange thing: first it checks up to 2048 MB, then up to 3046 MB, but further from 4096 to 5120 MB.

Nothing strange. Typically, a physical address range of 3 to 4GB is reserved for PCI devices.

to tell the kernel not to use a block of memory from 3046 MB to 4096, but how to do it?

The kernel does this. Look at the output of dmesg after loading, for the lines at the very beginning with the words e820.

Answer 2

Unfortunately. Samsung isn't the only manufacturer of wobbly motherboards. There are other models of beeches that do not support more than 3 Gig of memory, i.e. maximum 2+1. For Windows, no cure has been found, they just put up with it.

Answer 3

Recently, part of the RAM was not visible to me due to the fact that a small piece of adhesive tape was stuck to several contacts on one of the strips.
Just in case, check the cleanliness of the contacts, you never know ...