How logs will come to UART serial console?
Hi , Here is my question. when we put 'printk's in kernel code the logs will go to the log_buffer.(i observed that from implementation) But when UART is enabled(in the bootloader), the same printk logs are going to the serial console. As per my study printk doesnot implementing anything that writes to the UART console. Now here are my questions, how this is being achieved? Where this is implemented?(which file) Where wil be the parsing of the cmdline string sent from the bootloader is done? Thanking you, sandeep kumar.
On Tue, May 17, 2011 at 3:52 PM, sandeep kumar <coolsandyforyou@gmail.com> wrote:
Hi , Here is my question. when we put 'printk's in kernel code the logs will go to the log_buffer.(i observed that from implementation) But when UART is enabled(in the bootloader), the same printk logs are going to the serial console. As per my study printk doesnot implementing anything that writes to the UART console.
Now here are my questions, how this is being achieved? Where this is implemented?(which file)
console_unlock() in kernel/printk.c
Where wil be the parsing of the cmdline string sent from the bootloader is done?
Thanking you, sandeep kumar. _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Hi sandeep, On Tue, May 17, 2011 at 12:52 AM, sandeep kumar <coolsandyforyou@gmail.com> wrote:
Hi , Here is my question. when we put 'printk's in kernel code the logs will go to the log_buffer.(i observed that from implementation) But when UART is enabled(in the bootloader), the same printk logs are going to the serial console. As per my study printk doesnot implementing anything that writes to the UART console.
Now here are my questions, how this is being achieved? Where this is implemented?(which file)
When you register your UART driver there is typically an option to register a console driver at the same time. For example, let's take a look at the 8250 serial driver. We'll look at the file drivers/serial/8250.c Search for the function serial8250_console_init, which has a call to register_console. That's the starting point that sets up the console driver. You can have other drivers call register_console and get your console messages sent out whatever bizarre device you may have connected to your system. You can also have multiple consoles registered at the same time.
Where wil be the parsing of the cmdline string sent from the bootloader is done?
The function console_setup is called when the console= parameter is passed on the kernel command line. <http://lxr.linux.no/linux+v2.6.38/kernel/printk.c#L904> The __setup just after the end of the function is what causes it to call that function when the console= parameter is passed. -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com
participants (3)
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Dave Hylands -
Haojian Zhuang -
sandeep kumar