GDB

x86 debug registers (DR0-DR7)

x86 Debug Registers
 DR0-DR3: Store breakpoint register
 DR4,DR5: Reserved
 DR6:     Status register
 DR7:     Control register, flags:
 ------------------------------------------------------
                                  | Type | Length |
                                  |              /
                                  |             /
                                  |            /
                                  |           /
                                  |          /
                                  |         /
                                  |        /
                                  |       /
                                  |      /
                                  |     |
                                   16 18 20 22 24 26 28 30
  0 1 2 3 4 5 6 7       8-15       17 19 21 23 25 27 29 31
 |L|G|L|G|L|G|L|G|                |T |L |T |L |T |L |T |L |
 +--------------------------------------------------------+
 |D|D|D|D|D|D|D|D|                |D |D |D |D |D |D |D |D |
 |R|R|R|R|R|R|R|R|                |R |R |R |R |R |R |R |R |
 |0|0|1|1|2|2|3|3|                |0 |0 |1 |1 |2 |2 |3 |3 |
      Enable                      Type: Breakpoint type (00 execute, 01 write, 11 read-write)
                                Length: Breakpoint length (00 1-byte, 01 2-bytes, 11 4-bytes)