Am 26.06.2010 13:40, schrieb Robert P. J. Day: > On Sat, 26 Jun 2010, Mulyadi Santosa wrote: > >> Hi... >> >> On Sat, Jun 26, 2010 at 03:53, Chris <chris.maier85@xxxxxx> wrote: >>> I read the pages 83-90 in the LDD3 and the sources >>> (http://lxr.linux.no/#linux+v2.6.34/include/linux/proc_fs.h). >>> >>> Now, I am a little confused. The struct proc_dir_entry contains a >>> struct file_operations. Thus I can implement all standard file >>> operations on a proc file entry? >> >> AFAIK, only read and write (if it is meant to be writeable). Note: >> these days you need to use sequential write and read. refer to Rob >> PJ Day's articles on how to do such thing. Rob, please, go ahead on >> this... > > not only read and write -- you can certainly also implement lseek. , > at the very least. and even though it's getting a bit dated, /proc > files are covered fairly well in LDD3, which is available online at > http://lwn.net/Kernel/LDD3/. see chapter 4. > > also, you don't *need* to use the seq_file implementation, that's > just a newer way to use proc files that gets around an old length > limitation on how much you could print from a single proc file. but > there are still lots of examples of the older interface in the kernel > the last time i looked. read that chapter in LDD3, it explains it > fairly well. and here's where i become a bit conflicted. > > ironically (and i'm trying very hard not to be self-serving again), > i just happen to be writing the section on proc files for my online > kernel programming course so while i'm happy to still answer basic > questions here, i feel like i have to limit myself to not reproducing > everything i'm going to put in that section, since that would be > unfair to the registered students who've paid for the course. > > argh. i hate conflicts of interest. but read LDD3, it's a very > good coverage of proc files. > > rday > ok, and why they hold a file_operations struct in the proc_dir_entry struct if they only implement read, write and lseek? Thanks, Chris -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
