Bochs调试手册(英)

8.11. Using Bochs internal debugger

Note, if you are looking for a graphical front-end for the bochs debugger, you may want to check out BFE. This is a package written by a Bochs user which can interface with the text based Bochs debugger. No linking is necessary. It's not part of Bochs, but you may find it useful.

You can now conditionally compile in a GDB like command line debugger, that allows you to set breakpoints, step through instructions, and other useful functions. If there isn't a command for something you believe is generally useful for the debugger, let me know and I'll implement it if possible.

To use the debugger, you must configure Bochs with the --enable-debugger and --enable-disasm flags. For example:

  ./configure --enable-debugger --enable-disasm

Note: You must use flex version 2.5.4 or greater. I have heard that version 2.5.2 will not work.

When you first start up Bochs, you will see the command line prompt

  bochs:1>

From here, you may use the following commands:

8.11.1. Execution Control

  c                           continue executing  continue  s     [count]               execute count instructions, default is 1  step  [count]  stepi [count]  Ctrl-C                      stop execution, and return to command line prompt  Ctrl-D                      if at empty line on command line, exit  q                           quit debugger and execution  quit  exit

8.11.2. BreakPoints

  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  bpe    n                    Enable a breakpoint  bpd    n                    Disable a breakpoint  delete n                    Delete a breakpoint  del    n  d      n

8.11.3. Manipulating Memory

  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 CRC32 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)

8.11.4. Info commands

  info r|reg|regs|registers    List of CPU integer registers and their contents  info cpu                     List of all CPU registers and their contents  info fpu                     List of all FPU registers and their contents  info sse                     List of all SSE registers and their contents  info cr                      Show CR0-4 registers and their contents  info eflags                  Show decoded EFLAGS register  info break                   Information about current breakpoint status  info tab                     Show paging address translation

8.11.5. Manipulating CPU Registers

  set reg = expr    Change a CPU register to value of expression.                    Currently only general purpose registers are supported,                    you may not change:                      eflags, eip, cs, ss, ds, es, fs, gs.    Examples: set eax = 2+2/2              set esi = 2*eax+ebx  registers         List of CPU registers and their contents  regs  reg  r  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"    "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".

8.11.6. Disassembly commands

  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.  disassemble switch-mode     Switch between Intel and AT&T disassebly styles                              for debugger disassembler.  disassemble size = n        Tell debugger what segment size to use when                              the "disassemble" command is used.  Use values                              of 0, 16 or 32 for n.  Value of 0 means      "use segment size specified by current CS      segment". Default is 0.  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 the "disassemble size" variable is                              ignored.  set disassemble on          The same as 'set $auto_disassemble = 1'  set disassemble off         The same as 'set $auto_disassemble = 0'

8.11.7. Instruction tracing

  trace on                    Disassemble every executed instruction. Note                              that instructions which caused exceptions are                              not really executed, and therefore not traced.  trace off                   Disable instruction tracing.

8.11.8. Instrumentation

To use instrumentation features in bochs, you must compile in support for it. You should build a custom instrumentation library in a separate directory in the "instrument/" directory. To tell configure which instrumentation library you want to use, use the "--enable-instrumentation" option. The default library consists of a set of stubs, and the following are equivalent:

  ./configure [...] --enable-instrumentation  ./configure [...] --enable-instrumentation="instrument/stubs"

You could make a separate directory with your custom library, for example "instrument/myinstrument", copy the contents of the "instrument/stubs" directory to it, then customize it. Use:

  ./configure [...] --enable-instrumentation="instrument/myinstrument"

8.11.9. Instrumentation commands

  instrument start            calls bx_instr_start()  instrument stop             calls bx_instr_stop()  instrument reset            calls bx_instr_reset()  instrument print            calls bx_instr_print()

8.11.10. Other Commands

ptime

Print the current time (number of ticks since start of simulation).

sb delta

Insert a time break point "delta" instructions into the future ("delta" is a 64-bit integer followed by "L", for example 1000L).

sba time

Insert a time break point at "time" ("time" is a 64-bit integer followed by "L", for example 1000L).

record filename

Record console input to file filename. The file consists of zero or more lines of the form "%s %d %x", where the first word is the event type, the second is a time stamp and the third is event specific data.

playback filename

Playback console input from file filename. Additional input can be given directly in the console window. Events in the file will be played back at times relative to the time when the playback command was executed.

print-stack [num words]

Print the num words top 16-bit words on the stack. Num words defaults to 16. Only works reliably in protected mode when the base address of the stack segment is zero.

watch stop

Stop the simulation (and return to prompt) when a watch point is encountered.

watch continue

Do not stop the simulation when watch points are encountered. They will still be logged.

watch

Print current watch point status.

unwatch

Remove all watch points.

watch read address

Insert a read watch point at physical address address.

watch write address

Insert a write watch point at physical address address.

unwatch read address

Remove read watch point from physical address address.

unwatch write address

Remove write watch point from physical address address.

modebp

Toggles CPU mode switch breakpoint.

load-symbols [global] filename [offset]

Load symbols from file filename. If the global keyword is added, then the the symbols will be visible in all contexts for which symbols have not been loaded. Offset (default is 0) is added to every symbol entry. The symbols are loaded in the current (executing) context.

The symbol file consists of zero or more lines of the format

"%x %s"

.

show [string]

  Toggles show symbolic info (calls to begin with).  show - shows current show mode  show mode     - show, when processor switch mode  show int      - show, when interrupt is happens  show call     - show, when call is happens  show ret      - show, when iret is happens  show off      - toggles off symbolic info  show dbg-all  - turn on all show flags  show dbg-none - turn off all show flags