My Tech notes

Example usage OF Creating & Working On a CVS Branch Tried working hard on CVs commands, here is simple example for working in branch using CVS, CVS is becoming nomore use with everyone opting for SVN, still CVS usages is wide as it is old, Lets start with CVS commands to create a branch This is done with two commands, cvs tag -b release-1 //create branch cvs update -j release-1 //merge the changes in main tot Lets see with simple example Creating and working on a branch for the existing kernel source. #cvs co kernel/linux-2.6.26 #cd kernel/linux-2.6.26/ #cvs tag -b release-1 First we created a branch to the kernel source, as we are doing first release. Continue your development work for second release. After some time, reported a problem in the first release. So you need to Get the kernel source code of first release. #cvs co -r release-1 kernel/linux-2.6.24 and fix the problems Now If you want to merge these changes in to main trunk. #cvs update -j release-1 And you are done with ...

SMB write performance can be increased by Tuning the buffer cache. The secret to good performance is to keep as much of the data in memory for as long as is possible. Writing to the disk is the slowest part of any filesystem. If you know that the filesystem will be heavily used, then you can tune this process for Linux Samba. writing out dirty blocks to the disk until the filesystem buffer cache is 80 percent full (80). default is 40%, source = http://tldp.org/LDP/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3/chap29sec287.html by writing echo 80 > /proc/sys/vm/dirty_ratio I am getting around 2MB increase while write operation, tested in Xp. I have tried with this single option, as the ref source is for linux 2.2 and we are using 2.6 kernel. we can try out Linux General Optimization suggested at http://tldp.org/LDP/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3/gen-optim.html Tried with smb.conf, I am getting around 1MB gain while read and write. socket options = TCP_NODELAY I...

STEPS FOR CROSS COMPILING X11 FOR ARM Go to /usr/X11R6/lib in my linux PC. 1) install ARM toolchain, If not installed 2) Get x11 source from http://www.x.org/ 3) extract all the tar files, using tar -xvzf 4) edit cross.def and host.def files, in cross.def set the paths of tool chain in host.def file set crossCompile to YES and DoLoadableServer to NO 5) make shadow directory "build" and link to xc "lndir ../xc" 6) run Make World error: linux_vm86.c 281 impossible constraint in 'asm' 268 res might be used uninitialized in this function. fix:comment line 281, set res=0 error: implicit decleration of function 'SET_FLAG' fix: comment line 111 in programs/Xserver/hw/xfree86/os-support/linux/int10/helper_exec.c error:Undefined reference to XF86VidModeQueryVersion in glxinfo And glxgears Undefined reference to XF86VidModeQueryVersion in xdriinfo fix:download libXxf86vm.so.1.0 into our armtoolchain lib path and make softlinks ln -s libXxf86vm.so.1.0 li...

The Advancement of technology had entered into nanometer age. search in google define:Blue-ray will get wiki pages here is summary of it. Blu-ray Disc (also known as Blu-ray or BD) is an optical disc storage medium designed to supersede the standard DVD format. Its main uses are for storing PlayStation 3 games, high-definition video, and data storage, with up to 50 GB per disc. This is quite impressive, The disc has the same physical dimensions as standard DVDs and CDs. Why Blu-ray disc stores 50GB on same size of DVD/CD? Well here is advancement of laser technology, thanks to Shuji Nakamura for his invention on blue laser, The name Blu-ray Disc derives from the blue-violet laser used to read the disc. While a standard DVD uses a 650 nanometre red laser, Blu-ray uses a shorter wavelength, a 405 nm blue-violet laser, and allows for almost six times more data storage than on a DVD. check out about Blu-ray Movies - Everything about Blu-ray movies and releases .at http://www.blu-ra...

Get HyperSCSI for SAN - Storage Area Network SCSI (Small Computer Systems Interface) family of protocols. HyperSCSI can allow one to connect to and use SCSI and SCSI-based devices (like IDE, USB, Fibre Channel) over a network as if it was directly attached locally. Why HyperSCSI over iSCSI? The main advantage of HSCSI compared to iSCSI is especially a lower network load as well as an end system (server and client) load. TCP/IP SAN performance is still not good enough without hardware acceleration FC-based SANs cannot do Storage Wide-Area Networks Fully functional software implementation of both client and server so HSCSI can be used for a solution built on commonly available hardware, no expensive and specialized hardware is needed. Therefore, HSCSI can be used for building small and cheap SANs. HSCSI main disadvantage is this protocol has no official standard like iSCSI nd so it is unsupported in any way by manufacturers developing hardware data storage solutions. Two modes of oper...

As a kernel or device driver developer one must know what Linux kernel can not 1) No access to C library Generally, C library is large. Accessing a C lib function from kernel space is very time consuming. It affects the kernel speed and size. So many libc functions are implemented in the kernel. Just like printf in libc is implemented as printk in kernel. 2) The kernel lacks memory protection. Application in user space lacks memory protection. so when an application access illegal memory location, it results in segment violation. But when in kernel space segment violation occures, it results in oops. It is a major kernel error. 3) Difficult to use floating point. When floating point arithmetic is done in user space, kernel manages the transition from integer to floating point mode. But enabling floating point in kernel, the kernel requires manually saving and restoring the floating point register. It is extra overhead for kernel. 4) Limited and small stack Linux kernel has very small ...

Google Chrome OS is an open source, lightweight operating system. It is designed mainly considering netbooks. The notebooks will be available to consumers in mid 2010. This will be an open challenge to its rival MS Window. The key aspects of Google Chrome OS are its security, simplicity and speed.