need for user mode linux

need for user mode linux

[srinivas naga vutukuri]

Hi Manohar,

         Can get uses of user mode linux here.
http://user-mode-linux.sourceforge.net/uses.html

regards,
srinivas.

scancodes to X-Windows

[P.Manohar]

hai all,
The following is the code snippet from  drivers/char/keyboard.c

if ((raw_mode = (kbd->kbdmode == VC_RAW))) {
                 /*
                  *      The following is a workaround for hardware
                  *      which sometimes send the key release event twice
                  */
                 unsigned char next_scancode = scancode|up_flag;
                 if (up_flag && next_scancode==prev_scancode) {
                         /* unexpected 2nd release event */
                 } else {
                         prev_scancode=next_scancode;
                         put_queue(next_scancode);
                 }
                 /* we do not return yet, because we want to maintain
                    the key_down array, so that we have the correct
                    values when finishing RAW mode or when changing VT's */
         }

   I did so much googling, unable find 
My doubts are,

   1)Is in raw mode also the scancodes are send to tty buffer (as we are 
using put_queue() here.
   2) whether X will read from tty buffer are will it take scancodes 
directly ,in this case where it will store those scancodes,if X is busy doing
some other work.

In the put_queue function

#ifdef CONFIG_FORWARD_KEYBOARD
extern int forward_chars;

void put_queue(int ch)
{
         if (forward_chars == fg_console+1){
                 kbd_forward_char (ch);
         } else {
                 if (tty) {
                         tty_insert_flip_char(tty, ch, 0);
                         con_schedule_flip(tty);
                 }
         }
}

Where that kbd_forward_char is defined or what it will do.
what CONFIG_FORWARD_KEYBOARD signifies.
This is not present in my config file,(I am using RH linux 2.4.20)

I got confused of it , if you know about please mail me.

   Thanks&Regards,
   P.Manohar,

Re: need for user mode linux

[Parag Warudkar]

> 
> hai all,
>      I am a newbie to linux kernel module programming.I am going to work on
>   driver modification or calling some programs from driver. I heard about 
> usermode linux and its uses but I don't know the practical use of usermode 
> linux. Is it needed for me. How 
> it will be useful.Ofcourse, it need to be my personal decision, but I am 
> seeking decision or hints from experts like u.

UML - it is what it sounds like. Run Linux kernel as a user mode program inside a regular Linux operating system. It is generally good to use in situations as yours - learning and experimenting with kernel code without screwing up the hardware and host operating system. So you could do all your development and debugging on UML for instance and if it crashes due to your program error, no big deal just restart UML.

That being said, I am not sure if UML is in usable state with current kernels - Last time I tried I couldn't get it to run with 2.6.10 kernel.

You might want to check http://www.colinux.org - It is similar to UML, but instead of running Linux-under-Linux you run Linux-under-Windows. It is fairly simple to install and various distro images are available. Try out the documentation for colinux.

Parag

need for user mode linux

[Payasam Manohar]

hai all,
     I am a newbie to linux kernel module programming.I am going to work on
  driver modification or calling some programs from driver. I heard about 
usermode linux and its uses but I don't know the practical use of usermode 
linux. Is it needed for me. How 
it will be useful.Ofcourse, it need to be my personal decision, but I am 
seeking decision or hints from experts like u.

Note: please cc ur replies to my mail id.


   Thanks&Regards,

   P.Manohar.