ubuntu shows 27 gb ram out of 32 gb

free -m

 total used free shared buff/cache available
Mem: 27923 12347 6956 55 8620 14922
Swap: 0 0 0

Also I switch my gpu from intel to nvidia so there no additional ram to integrated graphics but I am still not sure

prime-select query
nvidia

I extended to 32 gb. System monitor says 27.3/32 gb.

dmesg | grep -i 'Memory:'
[ 0.038296] PM: hibernation: Registered nosave memory: [mem 0x00000000-0x00000fff]
[ 0.038297] PM: hibernation: Registered nosave memory: [mem 0x0009f000-0x000bffff]
[ 0.038298] PM: hibernation: Registered nosave memory: [mem 0x000c0000-0x000fffff]
[ 0.038299] PM: hibernation: Registered nosave memory: [mem 0x09a00000-0x09dfffff]
[ 0.038300] PM: hibernation: Registered nosave memory: [mem 0x09f00000-0x09f0efff]
[ 0.038301] PM: hibernation: Registered nosave memory: [mem 0xb4f50000-0xb4f50fff]
[ 0.038302] PM: hibernation: Registered nosave memory: [mem 0xb4f5d000-0xb4f5dfff]
[ 0.038302] PM: hibernation: Registered nosave memory: [mem 0xb4f5e000-0xb4f5efff]
[ 0.038303] PM: hibernation: Registered nosave memory: [mem 0xb4f71000-0xb4f71fff]
[ 0.038303] PM: hibernation: Registered nosave memory: [mem 0xb4f72000-0xb4f72fff]
[ 0.038304] PM: hibernation: Registered nosave memory: [mem 0xb4f81000-0xb4f81fff]
[ 0.038305] PM: hibernation: Registered nosave memory: [mem 0xb4f82000-0xb5090fff]
[ 0.038306] PM: hibernation: Registered nosave memory: [mem 0xb534a000-0xb534afff]
[ 0.038307] PM: hibernation: Registered nosave memory: [mem 0xb534f000-0xb534ffff]
[ 0.038308] PM: hibernation: Registered nosave memory: [mem 0xbab69000-0xbbd68fff]
[ 0.038309] PM: hibernation: Registered nosave memory: [mem 0xc9f7f000-0xccf7efff]
[ 0.038309] PM: hibernation: Registered nosave memory: [mem 0xccf7f000-0xcdf7efff]
[ 0.038310] PM: hibernation: Registered nosave memory: [mem 0xcdf7f000-0xcdffefff]
[ 0.038311] PM: hibernation: Registered nosave memory: [mem 0xce000000-0xcfffffff]
[ 0.038311] PM: hibernation: Registered nosave memory: [mem 0xd0000000-0xf7ffffff]
[ 0.038312] PM: hibernation: Registered nosave memory: [mem 0xf8000000-0xfbffffff]
[ 0.038312] PM: hibernation: Registered nosave memory: [mem 0xfc000000-0xfddfffff]
[ 0.038312] PM: hibernation: Registered nosave memory: [mem 0xfde00000-0xfdefffff]
[ 0.038313] PM: hibernation: Registered nosave memory: [mem 0xfdf00000-0xfdffffff]
[ 0.038313] PM: hibernation: Registered nosave memory: [mem 0xfe000000-0xfe0fffff]
[ 0.038313] PM: hibernation: Registered nosave memory: [mem 0xfe100000-0xfebfffff]
[ 0.038314] PM: hibernation: Registered nosave memory: [mem 0xfec00000-0xfec01fff]
[ 0.038314] PM: hibernation: Registered nosave memory: [mem 0xfec02000-0xfec0ffff]
[ 0.038315] PM: hibernation: Registered nosave memory: [mem 0xfec10000-0xfec10fff]
[ 0.038315] PM: hibernation: Registered nosave memory: [mem 0xfec11000-0xfec1ffff]
[ 0.038315] PM: hibernation: Registered nosave memory: [mem 0xfec20000-0xfec20fff]
[ 0.038316] PM: hibernation: Registered nosave memory: [mem 0xfec21000-0xfed7ffff]
[ 0.038316] PM: hibernation: Registered nosave memory: [mem 0xfed80000-0xfed81fff]
[ 0.038317] PM: hibernation: Registered nosave memory: [mem 0xfed82000-0xfedfffff]
[ 0.038317] PM: hibernation: Registered nosave memory: [mem 0xfee00000-0xfee00fff]
[ 0.038317] PM: hibernation: Registered nosave memory: [mem 0xfee01000-0xfeffffff]
[ 0.038318] PM: hibernation: Registered nosave memory: [mem 0xff000000-0xffffffff]
[ 0.082068] Memory: 28412460K/29208636K available (16393K kernel code, 3512K rwdata, 10492K rodata, 2904K init, 5724K bss, 795916K reserved, 0K cma-reserved)
[ 0.127150] Freeing SMP alternatives memory: 40K
[ 0.527562] Freeing initrd memory: 58156K
[ 0.792722] Freeing unused decrypted memory: 2036K
[ 0.793289] Freeing unused kernel image (initmem) memory: 2904K
[ 0.794020] Freeing unused kernel image (text/rodata gap) memory: 2036K
[ 0.794501] Freeing unused kernel image (rodata/data gap) memory: 1796K

I have uma frame buffer size in bios with options 1/2/4. I set from 4 to 2 gb. So now I have 30/32 gb. 29.2 gb actually.I don't know why on windows and ubuntu it doesn't change from amd graphics to nvidia. On lenovo in bios it has suitable graphics or only uma (amd). If I set to 1 gb it has 30/32gb ram.

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