When you first start up bochs, you will see the command line prompt
bochs:1>From here, you may use the following commands:
c Continue executing stepi [count] execute count instructions, default is 1 si [count] execute count instructions, default is 1 step [count] execute count instructions, default is 1 s [count] execute count instructions, default is 1 Ctrl-C stop execution, and return to command line prompt Ctrl-D if at empty line on command line, exit quit quit debugger and execution q quit debugger and execution
NOTE: The format of 'seg', 'off', and 'addr' in these descriptions,
are as follows. I don't have any way to set the current radix.
hexidecimal: 0xcdef0123
decimal: 123456789
octal: 01234567
vbreak seg:off Set a virtual address instruction breakpoint
vb seg:off
lbreak addr Set a linear address instruction breakpoint
lb addr
pbreak [*] addr Set a physical address instruction breakpoint
pb [*] addr (the '*' is optional for GDB compatibility)
break [*] addr
b [*] addr
info break Display state of all current breakpoints
delete n Delete a breakpoint
del n
d n
x /nuf addr Examine memory at linear address addr
xp /nuf addr Examine memory at physical address addr
n Count of how many units to display
u Unit size; one of
b Individual bytes
h Halfwords (2 bytes)
w Words (4 bytes)
g Giant words (8 bytes)
NOTE: these are *not* typical Intel nomenclature sizes,
but they are consistent with GDB convention.
f Printing format. one of
x Print in hexadecimal
d Print in decimal
u Print in unsigned decimal
o Print in octal
t Print in binary
n, f, and u are optional parameters. u and f default to the last values
you used, or to w(words) and x(hex) if none have been supplied.
n currently defaults to 1. If none of these optional parameters are
used, no slash should be typed. addr is also optional. If you don't
specify it, it will be the value the next address (as if you had
specified n+1 in the last x command).
setpmem addr datasize val Set physical memory location of size
datasize to value val.
crc addr1 addr2 Show CRC for physical memory range addr1..addr2
info dirty Show physical pages dirtied (written to) since last display
Values displayed are the top 20 bits only (page addresses)
info program Execution status of the program info registers List of CPU integer registers and their contents info break Information about current breakpoint status where Print the current call stack
set $reg = val Change a CPU register to value val. Registers may be one of:
eax, ecx, edx, ebx, esp, ebp, esi, edi.
Currently, you may not change:
eflags, cs, ss, ds, es, fs, gs.
Examples: set $eax = 0x01234567
set $edx = 25
info registers See Info section
dump_cpu Dump complete CPU state
set_cpu Set complete CPU state
Format of "dump_cpu" and "set_cpu":
"eax:0x%x\n"
"ebx:0x%x\n"
"ecx:0x%x\n"
"edx:0x%x\n"
"ebp:0x%x\n"
"esi:0x%x\n"
"edi:0x%x\n"
"esp:0x%x\n"
"eflags:0x%x\n"
"eip:0x%x\n"
"cs:s=0x%x, dl=0x%x, dh=0x%x, valid=%u\n"
"ss:s=0x%x, dl=0x%x, dh=0x%x, valid=%u\n"
"ds:s=0x%x, dl=0x%x, dh=0x%x, valid=%u\n"
"es:s=0x%x, dl=0x%x, dh=0x%x, valid=%u\n"
"fs:s=0x%x, dl=0x%x, dh=0x%x, valid=%u\n"
"gs:s=0x%x, dl=0x%x, dh=0x%x, valid=%u\n"
"ldtr:s=0x%x, dl=0x%x, dh=0x%x, valid=%u\n"
"tr:s=0x%x, dl=0x%x, dh=0x%x, valid=%u\n"
"gdtr:base=0x%x, limit=0x%x\n"
"idtr:base=0x%x, limit=0x%x\n"
"dr0:0x%x\n"
"dr1:0x%x\n"
"dr2:0x%x\n"
"dr3:0x%x\n"
"dr4:0x%x\n"
"dr5:0x%x\n"
"dr6:0x%x\n"
"dr7:0x%x\n"
"tr3:0x%x\n"
"tr4:0x%x\n"
"tr5:0x%x\n"
"tr6:0x%x\n"
"tr7:0x%x\n"
"cr0:0x%x\n"
"cr1:0x%x\n"
"cr2:0x%x\n"
"cr3:0x%x\n"
"cr4:0x%x\n"
"inhibit_int:%u\n"
"done\n"
Notes:
- s is the selector
- dl is the shadow descriptor low dword (4 byte quantitiy)
- dh is the shadow descriptor high dword (4 byte quantitiy)
- valid denotes if the segment register holds a validated shadow descriptor
- inhibit_int is set if the previous instruction was one which delays the
acceptance of interrupts by one instruction (STI, MOV SS)
- any errors encountered by the set_cpu command, are reported by
"Error: ...". They may be reported after any of the input lines,
or after the "done" line, during limit checks.
- A successful set_cpu command ends with the separate line:
"OK".
disassemble start end Disassemble instructions in given linear address
range, inclusive of start, exclusive of end.
Use "set $disassemble_size =" to tell
debugger desired segment size. Use a value for
end of less than start (or zero) if you only
want the first instruction disassembled.
set $disassemble_size = n Tell debugger what segment size to use when
the "disassemble" command is used. Use values
of 16 or 32 for n. Default is 32.
set $auto_disassemble = n Cause debugger to disassemble current instruction
every time execution stops if n=1. Default is 0.
Segment size of current CPU context is used for
disassembly, so variable "$disassemble_size" is
ignored.
The symbol file consists of zero or more lines of the format "%x %s".