September 2012 - kernelnewbies@kernelnewbies.org

How to understand the macro __init?
by 王哲 Sept. 3, 2012

Sept. 3, 2012

hi all in the kernel modules,we often use the macro __init. if we only discuss the __init for functions.__init tells the compiler to put the function in a special section.and the function are used once.So the code of this function should be freed from the memory after the first call. so i write a sample module: #include <linux/module.h> #include <linux/init.h> void __init print_k(void) { int k = 9; printk("<0>k = %d\n",k); } static int __init hello_init(void) { printk("<0>hello kernel!\n"); print_k(); print_k(); return 0; } static void __exit hello_exit(void) { printk("<0>bye kernel!\n"); } module_init(hello_init); module_exit(hello_exit); MODULE_LICENSE("GPL"); i use the __init for function print_k. in my opinion after the fisrt invoking the print_k in the hello_init. the memory of print_k will be freed,and the second invoking will not be executed.but the result of second invoking is executing . why? Thanks in advance! wanny

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Kernel booting problem.
by Sri Ram Vemulpali Sept. 2, 2012

Sept. 2, 2012

Hi All, I compiled my own kernel image with uclibc cross tool chain for x86 i686 arch. I am using grub as boot loader. these are the following parameters I am giving. kernel /bzImage ro root=/dev/VolGroup00/LogVol00 rhgb quiet init=/sbin/init initrd /initrd.img -----> this is cpio image of filesystem structure with needed modules and lib When I select at grub options to boot the kernel after reading bzImage grub proceeds to initrd and stuck at initrd. There is no output. I searched online and I found other kind of problems. But this is something different. Can anyone give some suggestions. Thanks in advance. -- Regards, Sri.

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map bss to addr zero
by Srinivas Ramanan Sept. 2, 2012

Sept. 2, 2012

Hi all, This is an interview question. "What is the implication of mapping BSS to the Virtual Memory Segment 0?" I was not able to find the answer from web. So posting here. thanks, srinivas

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