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Re: examining mmap()'d memory regions on linux
- To: <gdb at sourceware dot cygnus dot com>
- Subject: Re: examining mmap()'d memory regions on linux
- From: <j_clifton at aerosimulation dot com>
- Date: Mon, 05 Jun 2000 21:00:53 -0400
>Kevin Hilman wrote on 17 May 2000:
>> I have an app that reads/writes to an mmap()'d region. The data
>> is being read and written fine because it's getting to it's final
>> location (in this case a hardware device).
>> However, if I try to examine (via 'x') these memory regions in gdb, I
>> always get zeros.
>> Does gdb support mmap()'d regions?
>Not a GDB problem. GDB asks the kernel ``can I have memory at address X
>with process P''. If the kernel doesn't return it there is little GDB
>can do :-)
>As a work around, you may want to add a small function to your program
>that dumps out the relevant data. You can then call that from the gdb
Can you elaborate on what/how the kernel (ptrace) returns zero for mmapped
I read the ptrace.c code for i386 and didn't see the relationship between the
comments and mmap. I have the same problem with unable to examine a PCI
reflective memory. I also tried a program which just mallocs memory and I
couldn't see it's contents either.