How Windows records drive letter assignments in the registry

This information is recorded under the [HKEY_LOCAL_MACHINE\\SYSTEM\\MountedDevices] key-value, which is roughly (exported from my computer): Attachment 1

It is important here: Br>

"\\\\DosDevices\\\\R:"=hex:eb,f8,b2,92,00,7e,00,00,00,00,00,00

above R: indicates that the drive letter is R, and the following HEX value is divided into two parts. The first part is the first four HEX values, indicating the serial number of the hard disk to which the R partition belongs, and the next eight HEXs indicate the offset start of the R partition on the hard disk. Location, in bytes. Control above R, look at the hard disk sector 0 R partition belongs:

Offset 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

000000000 33 C0 8E D0 BC 00 7C FB 50 07 50 1F FC BE 1B 7C 000000010 BF 1B 06 50 57 B9 E5 01 F3 A4 CB BD BE 07 B1 04 000000020 38 6E 00 7C 09 75 13 83 C5 10 E2 F4 CD 18 8B F5 000000030 83 C6 10 49 74 19 38 2C 74 F6 A0 B5 07 B4 07 8B 000000040 F0 AC 3C 00 74 FC BB 07 00 B4 0E CD 10 EB F2 88 000000050 4E 10 E8 46 00 73 2A FE 46 10 80 7E 04 0B 74 0B 000000060 80 7E 04 0C 74 05 A0 B6 07 75 D2 80 46 02 06 83 000000070 46 08 06 83 56 0A 00 E8 21 00 73 05 A0 B6 07 EB 000000080 BC 81 3E FE 7D 55 AA 74 0B 80 7E 10 00 74 C8 A0 000000090 B7 07 EB A9 8B FC 1E 57 8B F5 CB BF 05 00 8A 56 0000000A0 00 B4 08 CD 13 72 23 8A C1 24 3F 98 8A DE 8A FC 0000000B0 43 F7 E3 8B D1 86 D6 B1 06 D2 EE 42 F7 E2 39 56 0000000C0 0A 77 23 72 05 39 46 08 73 1C B8 01 02 B B 00 7C 0000000D0 8B 4E 02 8B 56 00 CD 13 73 51 4F 74 4E 32 E4 8A 0000000E0 56 00 CD 13 EB E4 8A 56 00 60 BB AA 55 B4 41 CD 0000000F0 13 72 36 81 FB 55 AA 75 30 F6 C1 01 74 2B 61 60 000000100 6A 00 6A 00 FF 76 0A FF 76 08 6A 00 68 00 7C 6A 000000110 01 6A 10 B4 42 8B F4 CD 13 61 61 73 0E 4F 74 0B 000000120 32 E4 8A 56 00 CD 13 EB D6 61 F9 C3 49 6E 76 61 000000130 6C 69 64 20 70 61 72 74 69 74 69 6F 6E 20 74 61 000000140 62 6C 65 00 45 72 72 6F 72 20 6C 6F 61 64 69 6E 000000150 67 20 6F 70 65 72 61 74 69 6E 67 20 73 79 73 74 000000160 65 6D 00 4D 69 73 73 69 6E 67 20 6F 70 65 72 61 000000170 74 69 6E 67 20 73 79 73 74 65 6D 00 00 00 00 00 000000180 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000000190 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0000001A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0000001B0 00 00 00 00 00 2C 44 63 EB F8 B2 92 00 00 00 01 0000001C0 01 00 07 FE FF FF 3F 00 00 00 3F F5 7F 0C 00 00 0000001D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0000001E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0000001F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 AA & lt;

FIG offset is 0x1B8 ~ 0x1BB, content HEX: EB F8 B2 92 is recorded in the registry partition R Hard disk serial number. As can be seen from the first component table in the offset 0x1be~0x1ce, the unique partition start position is 0x3F, in sector units, and the byte is 0x3F*0x200=0x7E00, if 8 bytes are used. The 64-bit value indicates that HEX is 00 7E 00 00 00 00 00 00 , which is the second half of the key value recorded in the registry.