Programs and patches
AMD64 registers
A compact reference to AMD64 register names, numbering, and use.
Last updated · 20 July 2007
Register names, numbers and purposes on the
AMD64 architecture running Linux.
For more information see AMD64 ABI.
| Description | RAX | RBX | RCX | RDX | RSI | RDI | RBP | RSP | R8 | R9 | R10 | R11 | R12 | R13 | R14 | R15 | RIP/RA |
| Dwarf2 number | 0 | 3 | 2 | 1 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Preserved across function calls | Yes | Yes | Yes | Yes | Yes | Yes | Yes | N/A | |||||||||
| Function parameter | 4th | 3rd | 2nd | 1st | 5th | 6th | N/A | ||||||||||
| Return register | 1st | 2nd | N/A | ||||||||||||||
| Kernel parameter | #NR | 3rd | 2nd | 1st | 5th | 6th | 4th | N/A |