为什么gdb认为我的x86-64程序是i386？

Question

我正在尝试调试64位程序，但gdb似乎认为它具有i386体系结构。

# file /usr/local/bin/foo
/usr/local/bin/foo: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.4.0, not stripped


# gdb --args foo bar
GNU gdb (GDB) 7.3.1
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/local/bin/foo...done.
(gdb) set debug arch 1
(gdb) show debug arch
Architecture debugging is 1.
(gdb) info target
Symbols from "/usr/local/bin/foo".
Local exec file:
gdbarch_find_by_info: info.bfd_arch_info i386:x86-64
gdbarch_find_by_info: info.byte_order 1 (little)
gdbarch_find_by_info: info.osabi 5 (GNU/Linux)
gdbarch_find_by_info: info.abfd 0xaf4a90
gdbarch_find_by_info: info.tdep_info 0x0
gdbarch_find_by_info: Previous architecture 0xb05790 (i386:x86-64) selected
    `/usr/local/bin/foo', file type elf64-x86-64.
    Entry point: 0x419730
    0x00000000004001c8 - 0x00000000004001e4 is .interp
    0x00000000004001e4 - 0x0000000000400204 is .note.ABI-tag
    0x0000000000400208 - 0x0000000000402560 is .hash
    0x0000000000402560 - 0x0000000000409898 is .dynsym
    0x0000000000409898 - 0x0000000000411188 is .dynstr
    0x0000000000411188 - 0x0000000000411b22 is .gnu.version
    0x0000000000411b28 - 0x0000000000411b88 is .gnu.version_r
    0x0000000000411b88 - 0x00000000004181a0 is .rela.dyn
    0x00000000004181a0 - 0x0000000000418e78 is .rela.plt
    0x0000000000418e78 - 0x0000000000418e90 is .init
    0x0000000000418e90 - 0x0000000000419730 is .plt
    0x0000000000419730 - 0x00000000004ede38 is .text
    0x00000000004ede38 - 0x00000000004ede46 is .fini
    0x00000000004ede48 - 0x00000000004ede4c is .eh_frame
    0x00000000006ee000 - 0x00000000006ee010 is .ctors
    0x00000000006ee010 - 0x00000000006ee020 is .dtors
    0x00000000006ee020 - 0x00000000006ee028 is .jcr
    0x00000000006ee028 - 0x00000000006ee1f8 is .dynamic
    0x00000000006ee1f8 - 0x00000000006f07f0 is .got
    0x00000000006f07f0 - 0x00000000006f0c50 is .got.plt
    0x00000000006f0c50 - 0x0000000000736c70 is .data
    0x0000000000736c70 - 0x000000000073b420 is .bss
(gdb) start
Temporary breakpoint 1 at 0x419e70: file foo.lpr, line 69.
Starting program: /usr/local/bin/foo bar
warning: Selected architecture i386:x86-64 is not compatible with reported target architecture i386
gdbarch_find_by_info: info.bfd_arch_info i386:x86-64
gdbarch_find_by_info: info.byte_order 1 (little)
gdbarch_find_by_info: info.osabi 5 (GNU/Linux)
gdbarch_find_by_info: info.abfd 0xaf4a90
gdbarch_find_by_info: info.tdep_info 0x0
gdbarch_find_by_info: Target rejected architecture
gdbarch_update_p: Architecture not found
warning: Architecture rejected target-supplied description
gdbarch_find_by_info: info.bfd_arch_info i386:x86-64
gdbarch_find_by_info: info.byte_order 1 (little)
gdbarch_find_by_info: info.osabi 5 (GNU/Linux)
gdbarch_find_by_info: info.abfd 0xd6ce90
gdbarch_find_by_info: info.tdep_info 0x0
gdbarch_find_by_info: Previous architecture 0xb05790 (i386:x86-64) selected
Error in re-setting breakpoint 1: Cannot access memory at address 0x419e60
Error in re-setting breakpoint 1: Cannot access memory at address 0x419e60
process 5299 is executing new program: /usr/local/bin/foo
warning: Selected architecture i386:x86-64 is not compatible with reported target architecture i386
gdbarch_find_by_info: info.bfd_arch_info i386:x86-64
gdbarch_find_by_info: info.byte_order 1 (little)
gdbarch_find_by_info: info.osabi 5 (GNU/Linux)
gdbarch_find_by_info: info.abfd 0xb21790
gdbarch_find_by_info: info.tdep_info 0x0
gdbarch_find_by_info: Target rejected architecture
Architecture of file not recognized.

注意警告：

warning: Selected architecture i386:x86-64 is not compatible with reported target architecture i386

然后：

gdbarch_find_by_info: Target rejected architecture
gdbarch_update_p: Architecture not found
warning: Architecture rejected target-supplied description

在gdb中，如果我输入“ set architecture”（设置架构）并点击tab，我将看到以下内容：

(gdb) set architecture 
auto               i386:intel         i386:x64-32:intel  i386:x86-64:intel  
i386               i386:x64-32        i386:x86-64        i8086

我的问题是：为什么gdb认为我的文件具有i386体系结构，即使它显然是x86-64二进制文件，我该怎么办？

我的程序是使用FreePascal版本2.6.0 编译的。

更新：在我的Ubuntu 12.04计算机（带有3.2.0-31内核）上，使用相同的gdb二进制文件和相同的freepascal二进制文件，我没有收到任何警告。我尝试调试的服务器正在运行2.6.34.10-24内核。会在内核或服务器上配置错误的东西来影响gdb吗？

Answer 1

你的问题从这里开始：

gdbarch_find_by_info：目标拒绝的架构

这意味着 GDB 中的目标相关代码不喜欢该i386:x86-64架构的某些内容。不幸的是，没有简单的方法来判断它不喜欢什么——您必须调试 GDB 本身才能找到答案。

你能在GDB失败的机器上调试其他二进制文件（例如）吗？/bin/date