Bochs调试手册(英)

客官°小女子只卖身不卖艺 2022-08-08 16:58 171阅读 0赞

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:

> 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

From here, you may use the following commands:

## 8.11.1. Execution Control ##

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</pre> </td> 
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## 8.11.2. BreakPoints ##

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
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## 8.11.3. Manipulating Memory ##

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   <td style="word-wrap:break-word; margin:0px; padding:0px"> <pre style="word-wrap:break-word; margin-top:0px; margin-bottom:0px; padding:0px">  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)
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## 8.11.4. Info commands ##

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   <td style="word-wrap:break-word; margin:0px; padding:0px"> <pre style="word-wrap:break-word; margin-top:0px; margin-bottom:0px; padding:0px">  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</pre> </td> 
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## 8.11.5. Manipulating CPU Registers ##

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".</pre> </td> 
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## 8.11.6. Disassembly commands ##

disassemble switch-mode     Switch between Intel and AT&amp;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'</pre> </td> 
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## 8.11.7. Instruction tracing ##

trace off                   Disable instruction tracing.</pre> </td> 
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## 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:

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:

## 8.11.9. Instrumentation commands ##

## 8.11.10. Other Commands ##

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

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

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

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 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 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.

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

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

Print current watch point status.

Remove all watch points.

Insert a read watch point at physical address address.

Insert a write watch point at physical address address.

Remove read watch point from physical address address.

Remove write watch point from physical address address.

Toggles CPU mode switch breakpoint.

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

[BFE]: http://bfe.sourceforge.net/