Attaching and inspecting crash with gdb

[Devrim Erdem]

I have just tried to use the generate-core-file function with 5.2.1. 

I attached to the crashed application and saved a core file. This
works fine. Then I start gdb with this core and the same executable
like :

gdb myExec core.13979

I get the warning :
    warning: core file may not match the specified executable file.

Then I get messages like :
    Cannot access memory at address 0xbf7ff954

when I use frame or where commands.

Any hints maybe for this problem ?