[okl4-developer] Using an iguana server from wombat HowTo

[Jorge Torres]

HI Remy,

These howtos are great,

All the best,

Jorge

On Mon, Mar 31, 2008 at 12:31 PM, Remy Gottschalk <rgottschalk at linagora.com>
wrote:

> Hi again
>
> This howto directly follows the previous one (HelloWorld Iguana server
> HowTo) and explain how interacting with the helloworld server from wombat.
> The next will probably deal with more elaborate communication and shared
> memory.
>
>
> ----------------------------
> Using the server from Wombat
> ----------------------------
>
> Now we have a functional hello server we will use it from the
> para-virtualized Linux. We will do so using a new entry in /proc.
>
>  1 Library
>  ---------
>
> The first thing to do is to link the kernel to our client library
> libhello.a. To achieve this we simply add a -lhello flag to the kernel
> Makefile.
>
> $ cat linux/kernel-2.6.11-v2/arch/l4/Makefile
> [...]
> libs-y +=  -lvtimer -lvserial -ll4e -lll -liguana -ll4 -lgcc -lmutex
> -lcircular_buffer -lnaming -lhello
> [...]
>
>  2 A new module
>  --------------
>
> We will now create a new kernel module to allow use interacting with the
> server using a /proc entry.
> We will work directly in a hello folder in the kernel root in order to
> make things fast and easy.
>
> $ mkdir linux/kernel-2.6.11-v2/hello
> $ touch linux/kernel-2.6.11-v2/hello/Makefile
> $ touch linux/kernel-2.6.11-v2/hello/my_l4_hello.c
> $ ls  linux/kernel-2.6.11-v2/hello
> Makefile  my_l4_hello.c
>
> We need to modify the global Makefile :
> $ cat linux/kernel-2.6.11-v2/Makefile
> [...]
> core-y          := usr/ hello/
> [...]
> and create a new one for our source file.
> $ cat linux/kernel-2.6.11-v2/hello/Makefile
> obj-y += my_l4_hello.o
>
> Now here is the code for our module :
>
> $ cat linux/kernel-2.6.11-v2/hello/my_l4_hello.c
> #include <linux/module.h>
> #include <linux/kernel.h>
> #include <linux/proc_fs.h>
> #include <linux/string.h>
> #include <linux/vmalloc.h>
> #include <asm/uaccess.h>
>
> #include <hello/hello.h>
>
> /* Defines the license for this LKM */
> MODULE_LICENSE("GPL");
> MODULE_DESCRIPTION("L4 Hello Wrapper");
>
> static struct proc_dir_entry *proc_entry;
>
> int hello_read( char *page, char **start, off_t off,
>                  int count, int *eof, void *data )
> {
>  say_hello();
>  return 0;
> }
>
> int my_module_init( void )
> {
>  int ret = 0;
>
>  proc_entry = create_proc_entry( "hello", 0644, NULL );
>  if (proc_entry == NULL)
>    {
>      ret = -ENOMEM;
>      printk(KERN_INFO "fortune: Couldn't create proc entry\n");
>    }
>  else
>    {
>      proc_entry->read_proc = hello_read;
>      proc_entry->write_proc = hello_write;
>      proc_entry->owner = THIS_MODULE;
>      printk(KERN_INFO "<===== Hello Module Started =====>\n");
>    }
>  hello_init();
>  return ret;
> }
>
> void my_module_cleanup( void )
> {
>  remove_proc_entry("hello", &proc_root);
>  printk(KERN_INFO "<===== Hello Module Unloaded =====>\n");
>  return;
> }
>
> module_init( my_module_init );
> module_exit( my_module_cleanup );
>
> This module creates a new entry in /proc (/proc/hello) and calls say_hello
> on each reading access.
>
> We can see that using our server is pretty simple, three line are
> concerned :
> #include <hello/hello.h>
> To include user library headers
> hello_init();
> In order to initiate the communication.
> say_hello();
> To interact with our server.
>
>  3 Final test
>  ------------
>
> We compile and test :
>
> $ ./tools/build.py machine=ia32_pc99 project=iguana wombat=True
> toolprefix=i686-unknown-linux-gnu- simulate
> [...]
> <===== Hello Module Started =====>
> [...]
> <===== Hello Server Started =====>
> [...]
> Please press Enter to activate this console.
>
> BusyBox v1.00 (2008.03.28-14:47+0000) Built-in shell (ash)
> Enter 'help' for a list of built-in commands.
>
> / #  cat /proc/hello
> I say hello
> / #
>
>
>
>
>
>
> --
> Remy Gottschalk - rgottschalk at linagora.com
> Ingénieur informatique embarquée
> Groupe LINAGORA - http://www.linagora.com
> Tél.: +33(0)1 58 18 68 28 - Fax : +33(0)1 58 18 68 29
>
>
>
> _______________________________________________
> Developer mailing list
> Developer at okl4.org
> https://lists.okl4.org/mailman/listinfo/developer
>
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