# which tool can check  variable value in a module in flight, not  in  crash file



## huiming cheng (Jul 16, 2020)

hi,
    I want to debug a .ko file like gdb, to run step by step. which tool can help this ?

    thanks in advance.


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## George (Jul 16, 2020)

Add some printfs to the source code, and recompile?

There is a chapter in the handbook on kernel debugging.








						Chapter 10. Kernel Debugging
					

FreeBSD Kernel Debugging




					www.freebsd.org


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