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    SubjectRe: [PATCH] Built kernel without -O2 option
    Date
    Hui Zhu <teawater@gmail.com> writes:

    > Now, there are a lot of ways to debug the Linux kernel with GDB, like
    > qemu, kgtp or kgdb and so on.
    > But the developer more like add a printk. It have a lot of reason, a big one is:
    > (gdb) p ret
    > $3 = <value optimized out>
    > And the code execution order is not right.

    Really the right place to fix a lot of this would be gcc (and perhaps
    gdb). I suspect with some careful work the debugging experience
    for -O2 could be improved a lot.
    I also believe the latest gccs already have improvements in this area.

    >
    > This is becuase the Kernel is bult with gcc -O2. Gcc will not
    > generate enough debug message with file with -O2.
    > So GDB cannot work very well with Linux kernel.
    >
    > So I make a patch that add a option in "Kernel hacking" called "Close
    > GCC optimization". It will make kernel be built without -O2.


    You need to at least keep aggressive inlining for header files,
    otherwise there will be too much code bloat and bad code.

    Like -O1 -finline-functions ?

    -Andi

    --
    ak@linux.intel.com -- Speaking for myself only.


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