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Why does gdb consider my x86-64 i386 program?

I'm trying to debug a 64-bit program, but gdb seems to believe that it has an i386 architecture.

# 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.

Pay attention to the warning:

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

and then:

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

In gdb, if I type 'set architecture' and hit tab, I see the following:

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

My question is: why does gdb believe that my file has an i386 architecture, although this is obviously an x86-64 binary, and what can I do to fix it?

My program was compiled using FreePascal version 2.6.0.

UPDATE: I am not getting any warnings using the same gdb binary and the same purepascal binary on my Ubuntu 12.04 machine (with kernel 3.2.0-31). The server I'm trying to debug on is starting the 2.6.34.10-24 kernel. Can something be configured incorrectly in the kernel or on the server, which will affect gdb?

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1 answer

Your problem starts here:

gdbarch_find_by_info: target rejected architecture

This means that the target code in GDB was not liked in the i386:x86-64 . Unfortunately, there is no easy way to tell what he did not like - you have to debug GDB itself to find out.

Is it possible to debug other binaries (e.g. /bin/date ) on a computer where GDB crashes?

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Source: https://habr.com/ru/post/1436670/

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