[Gdb-discuss] Why GDB can NOT read the content of memory protected(readonly) from the core file

[MCG LU Fengcheng]

Hello all
       When I use the GDB to analyze the core file, I encountered one problem.
In my program, some memory are protected readonly(use mprotect routine).
I want to use the gdb to check the content in these memory, But GDB always
show ZERO in these memory. For example:

(gdb) x/32b buf
0x80499a0 <buf>:        0x00    0x00    0x00    0x00    0x00    0x00    0x00      0x00
0x80499a8 <buf+8>:      0x00    0x00    0x00    0x00    0x00    0x00    0x00    0x00
0x80499b0 <buf+16>:     0x00    0x00    0x00    0x00    0x00    0x00    0x00   0x00
0x80499b8 <buf+24>:     0x00    0x00    0x00    0x00    0x00    0x00    0x00   0x00

In Fact, there MUST be non-ZERO data in these memory.

Why?

Best Regards
Lu Fengcheng

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