1KADB(4) 386BSD Programmer's Manual KADB(4) 2 3NNAAMMEE 4 kkddbb - kernel debugging facility 5 6SSYYNNOOPPSSIISS 7 ooppttiioonnss 8 KKAADDBB 9 10DDEESSCCRRIIPPTTIIOONN 11 KKddbb is a debugging facility for the kernel based on adb(1). KKddbb may be 12 used to symbolically examine and modify memory locations, set break- 13 points, and single step the system. 14 15 Several boot time options are used in conjunction with the debugger. To 16 ``enable'' the debugger, the system must be booted with the RB_KDB flag 17 (0x40) specified in the _b_o_o_t_h_o_w_t_o register. When the debugger is enabled 18 the system will read in and initialize the symbol table from the booted 19 system. If the RB_HALT flag (0x08) is also specified, the system will 20 enter the debugger at the earliest possible time to allow breakpoints to 21 be set before the system starts operation. From that point on, if the 22 RB_NOSYNC flag (0x04) is set, typing `^[k', `^[K', or `^[^K' at the con- 23 sole causes a trap into the debugger. 24 25 KKddbb supports most of the adb command language. The output formats `f', 26 `F', `Y', are not supported. The address space maps do not exist, thus 27 the `m', `m', and `m' commands do not exist. Shell escapes and command 28 files are not supported. The `r' and `k' commands make no sense and are 29 not recognized. Finally, the signal arguments to the continue and single 30 step commands are ignored. 31 32NNOOTTEESS 33 KKddbb normally runs at a priority level below the interrupt level of the 34 clock and all devices; the level of the highest priority software inter- 35 rupt. If the debugger is entered on the kernel's per-process stack at an 36 ipl below its normal operating level it automatically switches to the in- 37 terrupt stack to avoid potential overflow of the kernel stack. Should 38 the debugger operate on the kernel stack the message `(on kernel stack)' 39 will be printed on entry. 40 41 Note also that because kkddbb uses input from the console to force entry to 42 the debugger it may not be possible to force entry if the system hangs at 43 a priority level higher than the console receiver interrupt. 44 45SSEEEE AALLSSOO 46 adb(1) 47 48HHIISSTTOORRYY 49 The kkddbb debugging facility currently under development. 50 51BSD Experimental March 28, 1991 2 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67