16GB가 설치되었지만 12GB만 사용 가능

Fedora 34를 실행하는 Vega 8 그래픽이 탑재된 AMD Ryzen 7 PRO 5850U가 탑재된 ThinkPad P14s Gen 2 AMD가 있습니다. 16GB DIMM이 설치되어 있고 BIOS와 dmideocde가 모두 올바르게 보고됩니다.

Getting SMBIOS data from sysfs.
SMBIOS 3.3.0 present.
# SMBIOS implementations newer than version 3.2.0 are not
# fully supported by this version of dmidecode.

Handle 0x0001, DMI type 16, 23 bytes
Physical Memory Array
    Location: System Board Or Motherboard
    Use: System Memory
    Error Correction Type: None
    Maximum Capacity: 64 GB
    Error Information Handle: 0x0000
    Number Of Devices: 2

Handle 0x0008, DMI type 17, 92 bytes
Memory Device
    Array Handle: 0x0001
    Error Information Handle: 0x0007
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 16 GB
    Form Factor: SODIMM
    Set: None
    Locator: DIMM 0
    Bank Locator: P0 CHANNEL A
    Type: DDR4
    Type Detail: Synchronous Unbuffered (Unregistered)
    Speed: 3200 MT/s
    Manufacturer: Hynix
    Serial Number: 00000000
    Asset Tag: Not Specified
    Part Number: HMAB2GS6AMR6N-XN    
    Rank: 1
    Configured Memory Speed: 3200 MT/s
    Minimum Voltage: 1.2 V
    Maximum Voltage: 1.2 V
    Configured Voltage: 1.2 V
    Memory Technology: DRAM
    Memory Operating Mode Capability: Volatile memory
    Firmware Version: Unknown
    Module Manufacturer ID: Bank 1, Hex 0xAD
    Module Product ID: Unknown
    Memory Subsystem Controller Manufacturer ID: Unknown
    Memory Subsystem Controller Product ID: Unknown
    Non-Volatile Size: None
    Volatile Size: 16 GB
    Cache Size: None
    Logical Size: None

Handle 0x000B, DMI type 17, 92 bytes
Memory Device
    Array Handle: 0x0001
    Error Information Handle: 0x000A
    Total Width: Unknown
    Data Width: Unknown
    Size: No Module Installed
    Form Factor: Unknown
    Set: None
    Locator: DIMM 0
    Bank Locator: P0 CHANNEL B
    Type: Unknown
    Type Detail: Unknown
    Speed: Unknown
    Manufacturer: Null
    Serial Number: Null
    Asset Tag: Not Specified
    Part Number: Null
    Rank: Unknown
    Configured Memory Speed: Unknown
    Minimum Voltage: Unknown
    Maximum Voltage: Unknown
    Configured Voltage: Unknown
    Memory Technology: Unknown
    Memory Operating Mode Capability: Unknown
    Firmware Version: Unknown
    Module Manufacturer ID: Unknown
    Module Product ID: Unknown
    Memory Subsystem Controller Manufacturer ID: Unknown
    Memory Subsystem Controller Product ID: Unknown
    Non-Volatile Size: None
    Volatile Size: None
    Cache Size: None
    Logical Size: None

그러나 free, htop 등에서는 12GB만 사용 가능하다고 보고합니다.

               total        used        free      shared  buff/cache   available
Mem:        12063100     4728904     1619056      172620     5715140     6852240
Swap:        8388604           0     8388604

그래서 나머지 4GB가 어디에 없는지 살펴보고 memorydmesg에서 찾아보니

[    0.004454] ACPI: Reserving FACP table memory at [mem 0xc5993000-0xc5993113]
[    0.004455] ACPI: Reserving DSDT table memory at [mem 0xc597c000-0xc598d8ca]
[    0.004456] ACPI: Reserving FACS table memory at [mem 0xcbc19000-0xcbc1903f]
[    0.004456] ACPI: Reserving SSDT table memory at [mem 0xc7c9c000-0xc7c9c0a1]
[    0.004457] ACPI: Reserving SSDT table memory at [mem 0xc7c9a000-0xc7c9b18e]
[    0.004457] ACPI: Reserving SSDT table memory at [mem 0xc7c8c000-0xc7c93228]
[    0.004458] ACPI: Reserving IVRS table memory at [mem 0xc7c6a000-0xc7c6a1a3]
[    0.004458] ACPI: Reserving SSDT table memory at [mem 0xc7c38000-0xc7c38a41]
[    0.004459] ACPI: Reserving SSDT table memory at [mem 0xc7bb3000-0xc7bb3631]
[    0.004459] ACPI: Reserving TPM2 table memory at [mem 0xc7bb2000-0xc7bb2033]
[    0.004460] ACPI: Reserving POAT table memory at [mem 0xc7baf000-0xc7baf054]
[    0.004460] ACPI: Reserving BATB table memory at [mem 0xc7b9a000-0xc7b9a049]
[    0.004460] ACPI: Reserving HPET table memory at [mem 0xc5992000-0xc5992037]
[    0.004461] ACPI: Reserving APIC table memory at [mem 0xc5991000-0xc5991137]
[    0.004461] ACPI: Reserving MCFG table memory at [mem 0xc5990000-0xc599003b]
[    0.004462] ACPI: Reserving SBST table memory at [mem 0xc598f000-0xc598f02f]
[    0.004462] ACPI: Reserving WSMT table memory at [mem 0xc598e000-0xc598e027]
[    0.004463] ACPI: Reserving VFCT table memory at [mem 0xc596e000-0xc597b883]
[    0.004463] ACPI: Reserving SSDT table memory at [mem 0xc5968000-0xc596d353]
[    0.004464] ACPI: Reserving CRAT table memory at [mem 0xc5967000-0xc5967ebf]
[    0.004464] ACPI: Reserving CDIT table memory at [mem 0xc5966000-0xc5966028]
[    0.004465] ACPI: Reserving FPDT table memory at [mem 0xc7b9b000-0xc7b9b033]
[    0.004465] ACPI: Reserving SSDT table memory at [mem 0xc5965000-0xc5965148]
[    0.004466] ACPI: Reserving SSDT table memory at [mem 0xc5963000-0xc59644ba]
[    0.004466] ACPI: Reserving SSDT table memory at [mem 0xc5961000-0xc596257f]
[    0.004467] ACPI: Reserving SSDT table memory at [mem 0xc595d000-0xc5960972]
[    0.004467] ACPI: Reserving BGRT table memory at [mem 0xc595c000-0xc595c037]
[    0.004468] ACPI: Reserving UEFI table memory at [mem 0xcbc18000-0xcbc180d9]
[    0.004468] ACPI: Reserving SSDT table memory at [mem 0xc595b000-0xc595b051]
[    0.004469] ACPI: Reserving SSDT table memory at [mem 0xc7c98000-0xc7c9808f]
[    0.004469] ACPI: Reserving SSDT table memory at [mem 0xc7c97000-0xc7c979b4]
[    0.028600] Early memory node ranges
[    0.057390] PM: hibernation: Registered nosave memory: [mem 0x00000000-0x00000fff]
[    0.057392] PM: hibernation: Registered nosave memory: [mem 0x0009f000-0x0009ffff]
[    0.057392] PM: hibernation: Registered nosave memory: [mem 0x000a0000-0x000dffff]
[    0.057392] PM: hibernation: Registered nosave memory: [mem 0x000e0000-0x000fffff]
[    0.057393] PM: hibernation: Registered nosave memory: [mem 0x09c00000-0x09da0fff]
[    0.057394] PM: hibernation: Registered nosave memory: [mem 0x09f00000-0x09f0cfff]
[    0.057395] PM: hibernation: Registered nosave memory: [mem 0x995b4000-0x995b4fff]
[    0.057396] PM: hibernation: Registered nosave memory: [mem 0x995c1000-0x995c1fff]
[    0.057397] PM: hibernation: Registered nosave memory: [mem 0xc0587000-0xc0617fff]
[    0.057397] PM: hibernation: Registered nosave memory: [mem 0xc09bd000-0xc09bdfff]
[    0.057398] PM: hibernation: Registered nosave memory: [mem 0xc1bee000-0xc1beefff]
[    0.057399] PM: hibernation: Registered nosave memory: [mem 0xc4b7e000-0xcad7dfff]
[    0.057399] PM: hibernation: Registered nosave memory: [mem 0xcad7e000-0xcbd7dfff]
[    0.057400] PM: hibernation: Registered nosave memory: [mem 0xcbd7e000-0xcbdfdfff]
[    0.057401] PM: hibernation: Registered nosave memory: [mem 0xce000000-0xcfffffff]
[    0.057401] PM: hibernation: Registered nosave memory: [mem 0xd0000000-0xf7ffffff]
[    0.057401] PM: hibernation: Registered nosave memory: [mem 0xf8000000-0xfbffffff]
[    0.057402] PM: hibernation: Registered nosave memory: [mem 0xfc000000-0xfdbfffff]
[    0.057402] PM: hibernation: Registered nosave memory: [mem 0xfdc00000-0xfdcfffff]
[    0.057402] PM: hibernation: Registered nosave memory: [mem 0xfdd00000-0xfed7ffff]
[    0.057403] PM: hibernation: Registered nosave memory: [mem 0xfed80000-0xfed80fff]
[    0.057403] PM: hibernation: Registered nosave memory: [mem 0xfed81000-0xffffffff]
[    0.100832] Memory: 11910836K/12401088K available (16393K kernel code, 3512K rwdata, 9992K rodata, 2792K init, 5048K bss, 489992K reserved, 0K cma-reserved)
[    0.127550] Freeing SMP alternatives memory: 44K
[    0.250903] x86/mm: Memory block size: 128MB
[    0.453344] Non-volatile memory driver v1.3
[    0.636368] Freeing initrd memory: 41780K
[    0.705257] Freeing unused decrypted memory: 2036K
[    0.705739] Freeing unused kernel image (initmem) memory: 2792K
[    0.710554] Freeing unused kernel image (text/rodata gap) memory: 2036K
[    0.710723] Freeing unused kernel image (rodata/data gap) memory: 248K
[    1.449478] amdgpu 0000:07:00.0: amdgpu: Trusted Memory Zone (TMZ) feature enabled
[    1.545656] [drm] amdgpu: 4096M of VRAM memory ready
[    1.545659] [drm] amdgpu: 4096M of GTT memory ready.

여기서 흥미로운 점은 4GB가 전적으로 GPU용으로 예약된 것 같다는 것입니다(TMZ 때문에?). 나머지 4GB는 여기로 가나요?잃어버린? 그렇다면 이 문제를 해결할 수 있는 방법은 없을까요? (현명한 아이디어인가요?) 그렇지 않다면 나머지 4GB는 어디로 갔나요?

미리 감사드립니다 :)