Messages in this thread | | | Date | Mon, 29 Nov 2010 16:16:19 +0800 | From | Américo Wang <> | Subject | Re: [PATCH] Built kernel without -O2 option |
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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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