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Showing posts from September, 2012

Why Japan attacked Perl harbour

While reading about Sino-japan war.I found Japan was almost winning.Suddenly it attacked Perl Harbor.I could not find the motive.What Google search gave a result with details explanation. http://wiki.answers.com/Q/Why_did_the_Japanese_attack_Pearl_Harbor

Linux boot seqence in short

This the following minimum boot sequence  1) Bootloader loads the Kernel image to Ram      The image may be compressed or uncompressed.Uboot uses a special header in added        to the kernel image and make it as uImage. Using  mkimage we can make the image zImage/vmLinux 2) Ramdisk loaded in the memory, bootloader do that. 3) Control is given to kernel ,it also provides kernel arguments/command line options.Also bootlader set ramdisk as rootfs. Initial Rootfs filesystem may be of ext2 or minix format.   initramfs is the file can be unpacked by kerne l of following formats . . gzip ,  bzip2 ,  LZMA ,  XZ  and  LZO . 3) Then "linuxrc" ran from initial ramdisk. 4) The root device is changed to that specified in the kernel parameter. 5) The init program  /etc/init  is run which will perform the user configurable boot sequence. if rdinit is used then specified binary is called. qemu-system-arm -M versatilepb -m 128M -kernel linux-3.5.3/arch/arm/boot/uI

Difference of Compilers arm-none-linux-gnueabi and arm-none-eabi

I was confused between  arm-none-linux-gnueabi and arm-none-eabi .I didn't know where to use what. The gcc naming convention is like as below arch-vendor-(os-)-eabi so for  arm-none-linux-gnueabi is meant for the compilation to elf which uses linux. and  arm-none-eabi is meant for the compilation of the codes which will run on bare metal arm core. The difference is that they use library accordingly to compile the source codes. 

Oracle Virtual box upgradation issue

I recently tried to run Xubuntu 12.04 on virtualbox 1.2.0.It was working fine.Then due to some bug in my head :) tried to upgrade virtualbox to VirtualBox-4.2.0_RC3 from here . Now without uninstalling the previous version I installed it.It created problem.While running any Vms after installing extension pack it gave error [ " failed to load vmmr0.r0 (verr_ldr_mismatch_native)" ]. This issue is intially I couldn't solve.Later I solved the issue as following. Remove virtualBox ,remove folders from Program Files then removing "C:\Users\USERNAME\AppData\Local\VirtualStore\Program Files\Oracle\VirtualBox" {Need administrative privilege} Now install VBox freshly and import the virtual image projects/Disks.

Small Makefile tutorial

This Makefile tutorial by Alex is small but very useful. http://www.cprogramming.com/tutorial/makefiles_continued.html