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    SubjectRe: [PATCH] Built kernel without -O2 option
    2010/11/29 Américo Wang <xiyou.wangcong@gmail.com>:
    > On Mon, Nov 29, 2010 at 11:56:15AM +0800, Hui Zhu wrote:
    >>Hi,
    >>
    >>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.
    >>
    >>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.
    >>
    >>I built and use it in i386 and x86_64.  I will try to make it OK in other arch.
    >>
    >
    > The problem is that some functions _have to_ be inlined and gcc without -O2
    > doesn't inline them. Have check all the cases? I doubt.
    >
    > Also, what is size of vmlinux before applying your patch and after that?
    > Does it increase too much?
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