Printk

has the same syntax as , but somewhat different semantics. Like , accepts a format C-string argument and a list of value arguments. The following table lists each log level with its canonical meaning. When no log level is specified, the entry is logged as the default level which is typically , Log levels are defined in header file . No floating point support While printf supports formatting floating point numbers, printk does not, ==Implementation==

The function tries to lock the semaphore controlling access to the Linux system console. If it succeeds, the output is logged and the console drivers are called. If it is not possible to acquire the semaphore the output is placed into the log buffer, and the current holder of the console semaphore will notice the new output when they release the console semaphore and will send the buffered output to the console before releasing the semaphore. One effect of this deferred printing is that code which calls printk and then changes the log levels to be printed may break. This is because the log level to be printed is inspected when the actual printing occurs. ==References==