mingw-w64's GDB 64-bit/32-bit debugging

mingw-w64's GDB 64-bit/32-bit debugging

[Luis Machado]

Hi,

The configure files don't tell much other than the difference between 
hosts (mingw/mingw64).

Is a native mingw-w64 gdb capable of debugging 64-bit and 32-bit Windows 
processes or do we need a 32-bit gdb for a 32-bit process and a 64-bit 
gdb for a 64-bit process?

Doing some tests i noticed ming-w64's 64-bit GDB doesn't quite like the 
32-bit executable, choking on some 64-bit Windows symbol files and 
eventually getting an unexpected signal.

---

[New Thread 9536.0x2358]
Error while mapping shared library sections:
`C:\Windows\SYSTEM32\ntdll.dll': not in executable format: File format 
not recognized
Error while mapping shared library sections:
`C:\Windows\system32\wow64.dll': not in executable format: File format 
not recognized
Error while mapping shared library sections:
`C:\Windows\system32\wow64win.dll': not in executable format: File 
format not recognized
warning: Could not load shared library symbols for WOW64_IMAGE_SECTION.
Do you need "set solib-search-path" or "set sysroot"?
warning: Could not load shared library symbols for WOW64_IMAGE_SECTION.
Do you need "set solib-search-path" or "set sysroot"?
warning: Could not load shared library symbols for NOT_AN_IMAGE.
Do you need "set solib-search-path" or "set sysroot"?
warning: Could not load shared library symbols for NOT_AN_IMAGE.
Do you need "set solib-search-path" or "set sysroot"?
Error while mapping shared library sections:
`C:\Windows\system32\wow64cpu.dll': not in executable format: File 
format not recognized
[New Thread 9536.0x2740]
gdb: unknown target exception 0x4000001f at 0x401633

Thread 1 received signal ?, Unknown signal.
0x0009e0d8 in ?? ()
(gdb) info shared
 From        To          Syms Read   Shared Object Library
                         No          C:\Windows\SYSTEM32\ntdll.dll
                         No          C:\Windows\system32\wow64.dll
                         No          C:\Windows\system32\wow64win.dll
                         No          C:\Windows\system32\wow64cpu.dll
0x75080000  0x751546b4  Yes (*)     C:\Windows\SysWOW64\kernel32.dll
0x74be1000  0x74d55bac  Yes (*)     C:\Windows\SysWOW64\KernelBase.dll
0x742f1000  0x743ad7d8  Yes (*)     C:\Windows\SysWOW64\msvcrt.dll
(*): Shared library is missing debugging information.

Re: mingw-w64's GDB 64-bit/32-bit debugging

[Eli Zaretskii]

> From: Luis Machado <lgustavo@codesourcery.com>
> Date: Mon, 5 Dec 2016 20:36:50 -0600
> 
> Is a native mingw-w64 gdb capable of debugging 64-bit and 32-bit Windows 
> processes or do we need a 32-bit gdb for a 32-bit process and a 64-bit 
> gdb for a 64-bit process?

The latter, I'm afraid.

> Doing some tests i noticed ming-w64's 64-bit GDB doesn't quite like the 
> 32-bit executable, choking on some 64-bit Windows symbol files and 
> eventually getting an unexpected signal.

Yes, GDB doesn't yet have code that implements the protocol for
debugging WOW64 applications, and the unexpected and unhandled
exception you see is a sign of that.  I'm quite sure patches to that
effect will be appreciated.