Registers in x86 operating system
Preface
Recently I try to implement a 32-bit microkernel with zig, but I always forget the purpose of register, so record here.
General Purpose Registers
| 64-bit | 32-bit | 16-bit | 8 high bits | 8 low bits | Description |
|---|
| RAX | EAX | AX | AH | AL | Accumulator |
| RBX | EBX | BX | BH | BL | Base |
| RCX | ECX | CX | CH | CL | Counter |
| RDX | EDX | DX | DH | DL | Data |
| RSI | ESI | SI | N/A | SIL | Source |
| RDI | EDI | DI | N/A | DIL | Destination |
| RSP | ESP | SP | N/A | SPL | Stack Pointer |
| RBP | EBP | BP | N/A | BPL | Stack Base Pointer |
Pointer Registers
| 64-bit | 32-bit | 16-bit | Description |
|---|
| RIP | EIP | IP | Instruction Pointer |
Segment Registers
| 16-bit | Description |
|---|
| CS | Code Segment |
| DS | Data Segment |
| ES | Extra Segment |
| SS | Stack Segment |
| FS | General Purpose F Segment |
| GS | General Purpose G Segment |
Reference