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DateFri, 11 Aug 2000 16:11:59 +1000
FromDave Cecil <>
SubjectModule mapping to mem/kmem?
Firstly, please forgive me if the questions I ask are ignorant.  I'm on a 
steep learning curve at present.

I want to display the value of a variable in my loadable module, but of 
course gdb vmlinux /proc/kcore can't do that.

I believe that I should be able to get at that value via /dev/mem or 
/dev/kmem, given that I know the address of the variable.

The question is, how do I do that?  To reach that goal, using /dev/mem, I 
assume I need to determine where my module was loaded into physical 
memory.  My understanding is that kernel memory is contiguous and is a 
simple direct mapping from kernel virtual addresses to the physical 
addresses.  (I guess there may be a discontinuity between where the kernel 
proper is loaded and where modules are loaded though.)

Once I know where it's loaded, I should then be able to use od to dump the 
appropriate bytes.  eg. If it's loaded at 0x200000 (say) then if I dump the 
memory at 0x200000 + <my variable's offset from start of module> then I 
should get its value, right?
Is there another, better technique, maybe using kmem?

Any help or pointers are much appreciated.

Thanks,
Dave


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