On Tue, 2005-03-29 at 12:07 +0200, Christophe Lucas wrote: > Mandeep Sandhu (Mandeep_Sandhu@xxxxxxxxxxx) wrote: > > hi all, > > > > I had written a small character driver under kernel 2.4.20. > > For starters I had implemented it's read method only. This > > would put a constant string "hello" into the user-space > > buffer. The problem I'm seeing is that when i "cat" my device > > it does not print anything on the console (i.e cat and not the > > printk's in my driver...they get printed fine!). strace of cat > > shows that it calls my drivers read method twice...first time > > i copy the constant string into the user's buffer and return the > > bytes copied....and on the second invocation i return 0 as there's > > nothing more to read. strace shows cat writing out to the std. > > output after the first read....but nothing comes on the console!! > > if I put '\n' character in my constant string it prints out the > > string correctly! I'm guessing the newline char causes the o/p > > stream to be flushed....is this expected behavior?? > > > > TIA, > > -mandeep > hi christophe, i don't have my own userland prog........it's whatever cat is doing... so u mean cat could be using print instead of printf??? Amicalement :) -mandeep > If in your userland program, you print with a printf, it is normal, it > can not be print... > > man flush > > ~Christophe > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
