Linux on my Notebook does not use all of RAM

[lal12]

 

 

I own a Lenovo V155 Notebook with a Ryzen 3500U with 8GiB of RAM and I always noticed that Linux does not use all the RAM. So I digged a bit into this and found that the e820 and efi memory map do not list the complete memory. For one they have a few large holes and they don't seem to reach the end address of 8GiB.

reserve setup_data: [mem 0x0000000000000000-0x000000000009efff] usable
reserve setup_data: [mem 0x000000000009f000-0x000000000009ffff] reserved
reserve setup_data: [mem 0x00000000000e0000-0x00000000000fffff] reserved
reserve setup_data: [mem 0x0000000000100000-0x0000000009bfffff] usable
reserve setup_data: [mem 0x0000000009c00000-0x0000000009cd0fff] reserved
reserve setup_data: [mem 0x0000000009cd1000-0x0000000009efffff] usable
reserve setup_data: [mem 0x0000000009f00000-0x0000000009f0afff] ACPI NVS
reserve setup_data: [mem 0x0000000009f0b000-0x00000000b19f5017] usable
reserve setup_data: [mem 0x00000000b19f5018-0x00000000b1a02457] usable
reserve setup_data: [mem 0x00000000b1a02458-0x00000000b857dfff] usable
reserve setup_data: [mem 0x00000000b857e000-0x00000000bc77dfff] reserved
reserve setup_data: [mem 0x00000000bc77e000-0x00000000be77dfff] ACPI NVS
reserve setup_data: [mem 0x00000000be77e000-0x00000000be7fdfff] ACPI data
reserve setup_data: [mem 0x00000000be7fe000-0x00000000bf7fffff] usable
reserve setup_data: [mem 0x00000000bf800000-0x00000000bfffffff] reserved
reserve setup_data: [mem 0x00000000fd200000-0x00000000fd2fffff] reserved
reserve setup_data: [mem 0x00000000fed80000-0x00000000fed80fff] reserved
reserve setup_data: [mem 0x0000000100000000-0x00000001beffffff] usable

is the memory map from dmesg, which has (I guess) the following holes:

• 978MiB: 0xbfffffff-0xfd200000 (partially used by GPU)
• 27MiB: 0xfd2fffff-fed80000
• 18MiB: 0xfed80fff-0x100000000
• 410MiB: 0x1beffffff-0x1ffffffff (I would expect 0x1ffffffff as last address?)

I had a quick look into what grub's lsmmap and lsefimmap show and while they show all entries and not just the merged ones it has the same holes.

 

 

I don't really know whether windows used all memory, after I bought the notebook.

Unfortunately my BIOS has basically no settings not even for the GPUs shared memory size. But lshw -C display tells me it uses memory:c0000000-cfffffff memory:d0000000-d01fffff ioport:1000(Größe=256) memory:d0800000-d087ffff which is a bit more than 256MiB. Which is in one of the holes, but not uses all of it.

• Am I getting anything important wrong here?
• Is there any way to debug this further?
• Is there any way to manually specify further memory areas? (I guess by writing a kernel module? But besides that?)