Re: gdb and mmap

[Daniel Jacobowitz <drow@mvista.com>]

On Mon, May 13, 2002 at 02:19:31PM -0500, David Stroupe wrote:
> I am mmap()ing a memory range proovided by a driver.  In gdb if I do a 
> /x address I get an Cannot access memory at address 0x4001b000 error. 
> If on the other hand I do somethink like
> str = (char*) address;
> printf("%s\n", str);
> 
> I see the string that is stored in the address.
> 
> Is there a way for me to tell gdb that the mmap()ped address is a valid one?

This is not a bug in GDB but a limitation of your operating system. 
For instance, GNU/Linux chooses not to expose I/O mappings to ptrace(). 
I believe it can't generically be done safely, without some significant
kernel rewrite.

You can just write a function to peek at the address and call it via
'call' or 'print' at the GDB prompt.

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer