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howto:loader_o 2012/10/09 05:21 howto:loader_o 2017/09/06 17:34 current
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-. Your favorite jtftisicauion appeared to be on the net the easiest thing to be aware of. I say to you, I certainly get irked while people consider worries that they plainly do not know about. You managed to hit the nail upon the top and defined out the whole thing without having side effect , people can take a signal. Will likely be back to get more. Thanks+====== How-to loader.o to preform a kexec like operations ====== 
 + 
 +loader.o allow you to run a custom kernel, without the danger of having to reprogram your Flash ROM. It loads a new kernel into memory and jumps to it directly. 
 + 
 +===== Compiling loader.o ===== 
 + 
 +  - Get [[http://www.genbako.com/loader.o/org/loader.tar.gz|loader.o original source]] and optionally [[http://www.genbako.com/loader.o/loader.diff|patch for initrd problem]]. 
 +  - [[:howto:kernel_build#build_toolchain|Build a toolchain for cross compiling]]. 
 +  - In Makefile point ''INCLUDE = -isystem'' parameter to a **2.4.21-pre4** kernel header files! 
 +  - Fix ''gcc'' and ''ld'' entry in Makefile to meet your cross compiled toolchain. 
 +  - Apply initrd patch if you like. 
 +  - Run ''make'' 
 + 
 +===== Use pre-compiled loader.o ===== 
 +If you think that compiling loader.o by yourself is too much hassle then you can use a [[http://dns323.kood.org/downloads/people/sala/loader.o|pre-compiled loader.o]] 
 + 
 +===== Preparing proper kernel image for loading ===== 
 +For kernel building instructions look [[howto:kernel_build|kernel building wiki page]]. 
 + 
 +Before you start compiling kernel you should apply this patch, which is going to fix [[http://dns323.kood.org/forum/t850-building-kernel-loadero.html|memory detection problem]]. 
 +<code patch> 
 +--- arch/ppc/platforms/sandpoint_setup.c.orig 2007-08-09 18:02:58.000000000 -0400 
 ++++ arch/ppc/platforms/sandpoint_setup.c 2007-08-09 18:03:41.000000000 -0400 
 +@@ -451,8 +451,8 @@ 
 +  
 + /* This might be fixed in DINK32 12.4, or we'll have another 
 + * way to determine the correct memory size anyhow. */ 
 +- /* return mpc10x_get_mem_size(MPC10X_MEM_MAP_B); */ 
 +- return 16*1024*1024; 
 ++ return mpc10x_get_mem_size(MPC10X_MEM_MAP_B); 
 ++ /*return 16*1024*1024;*/ 
 + } 
 +  
 + static void __init 
 +</code> 
 +If you would like to use custom cmdline parameter for your kernel, for example "root=/dev/sda3" then you will also need this patch: 
 +  - Search for "#endif /* CONFIG_BLK_DEV_INITRD */" in arch/ppc/platform/sandpoint_setup.c 
 +  - Add following lines after "#endif /* CONFIG_BLK_DEV_INITRD */" line: 
 +<code>        if ( r6 ) 
 +        { 
 +              *(char *)(r7+KERNELBASE) = 0; 
 +              strcpy(cmd_line, (char *)(r6+KERNELBASE)); 
 +        } 
 +</code> 
 +After you have successfully built a kernel image you should note that the loader need the kernel to be in binary format. It can be done with powerpc-linux-objcopy command. 
 +<code>powerpc-linux-objcopy -O binary vmlinux</code> 
 + 
 +===== Using loader.o to load a kernel image ===== 
 +<code>sync;insmod /mnt/HD_a2/loader.o kernel=/mnt/HD_a2/vmlinux</code> 
 +or 
 +<code>sync;insmod /mnt/HD_a2/loader.o kernel=/mnt/HD_a2/vmlinux cmdline="root=/dev/sda3"</code> 
 + 
 +===== Use pre-compiled vmlinux ===== 
 +Pre-compiled vmlinux is available at [[http://dns323.kood.org/downloads/people/sala/vmlinux|here]]. 
 +It does support custom cmdline parameter. I does have usb and usb storage modules built in, <del>so it is possible to load operating system from usb stick</del>. This kernel image is optimized to boot [[:howto:chroot_gentoo|Gentoo linux]]. .config is available at [[http://dns323.kood.org/downloads/people/sala/loader.config|here]].\\ 
 +<del>To load from usb stick:</del> 
 +<code>sync;insmod /mnt/HD_a2/loader.o kernel=/mnt/HD_a2/vmlinux cmdline="root=/dev/sdb1"</code>

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