while writing/updating a pile of kernel courseware over the next couple of months, i'm interested in bolstering everything in the courseware with actual examples ripped from the source code, so students can see all of the concepts in action. for example, to show how to use seq_file to write a trivial read-only proc file, i always point at fs/proc/version.c: ===== start ===== #include <linux/fs.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/proc_fs.h> #include <linux/seq_file.h> #include <linux/utsname.h> static int version_proc_show(struct seq_file *m, void *v) { seq_printf(m, linux_proc_banner, utsname()->sysname, utsname()->release, utsname()->version); return 0; } static int version_proc_open(struct inode *inode, struct file *file) { return single_open(file, version_proc_show, NULL); } static const struct file_operations version_proc_fops = { .open = version_proc_open, .read = seq_read, .llseek = seq_lseek, .release = single_release, }; static int __init proc_version_init(void) { proc_create("version", 0, NULL, &version_proc_fops); return 0; } module_init(proc_version_init); ===== end ===== not surprisingly, students can *immediately* see how to use that as the basis to write their own. if i want to show a seq_file that is actually being used sequentially, i typically like to show how /proc/devices is implemented (see fs/proc/devices.c). anyway, you get the idea. it's a wide open invitation -- i'm just trying to collect really elegant examples from the kernel source code to explain various concepts. if you have any favourites, by all means, post them and i'll start collecting them somewhere public. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================