Is corefile support for missing on Win32?

Pedro Alves pedro@palves.net
Thu Jun 9 16:20:44 GMT 2022


On 2022-06-07 20:30, Simon Sobisch via Gdb wrote:
> Testing with MSYS2 generated mingw64 gcc 12.1 + gdb 12.1 resulted in "everything working" ...until I needed to create a core file.
> 
> (gdb) show arch
> The target architecture is set to "auto" (currently "i386:x86-64").
> (gdb) gcore test.core
> warning: cannot close "test.core": invalid operation
> Can't create a corefile
> 
> (with gnutarget auto, pei-x86-64 and pe-x86-64)
> 
> I see that the first error message comes from
>   gdb/gdb_bfd.c (gdb_bfd_close_warning)
> and the second from the default implementation
>   gdb/exec.c (make_corefile_notes)
> 
> 
> This issue seems to exists for longer as some SO question [1] asked about this over 5 years ago.
> 
> Further testing showed the same issue with same tools in MinGW x86 and with "good old MinGW" using GDB 7.6.1 / GCC 9.2.
> 
> Testing with cygwin-x64 (GDB 11.2) shows the same result.
> 

Native Windows GDB was never able to generate cores.  Basically because cores are ELF objects,
while Windows is PE, so it's kind of a foreign thing.

However, Cygwin comes with a separate utility that is able to dump cores in ELF format, and
Windows GDB is actually able to read those.  This utility is called "dumper".  See here:

  https://www.cygwin.com/cygwin-ug-net/dumper.html

Sources are here:

  https://cygwin.com/git/?p=newlib-cygwin.git;a=blob;f=winsup/utils/dumper.cc

If someone wanted to work on it, I don't see any obstacle to GDB's gcore command
itself generating an ELF core in the exact same format.

> I guess the system's minidump format cannot be processed with GDB, can it?

Unfortunately not.  Christian Biesinger did write a patch to add support for it while ago, though:

  https://sourceware.org/git/?p=binutils-gdb.git;a=shortlog;h=refs/heads/users/cbiesinger/minidump

AFAIK, this was never finished/contributed for proper inclusion, and I don't know how far
that is to being complete.


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