Problems while using divecomputer-simulator for linux

[Linus Torvalds]

On Sun, Mar 30, 2014 at 12:14 PM, Venkatesh Shukla IIT BHU
<venkatesh.shukla.eee11 at iitbhu.ac.in> wrote:
>
> I have done as you asked. The output is here : http://pastebin.com/E50ayiSs
>
> I have recently shifted to Fedora 20. It worked in Ubuntu earlier.

It does indeed look like some glibc idiocy. Sometimes I wonder what
the f*ck is wrong with libc people.

The kernel didn't actually complain at all, and what seems to happen
is that glibc tries to be "helpful", and after it has done the TCSETC
it does a TCGETC and compares the result. And notices that the PARENB

And it looks like it notices that it tried to *set* c_cflags to 0xfbb
but then it reads back c_cflags as 0xebb.

The difference is octal 0400, which is PARENB. Because under Linux,
pty's always do

        tty->termios.c_cflag &= ~(CSIZE | PARENB);
        tty->termios.c_cflag |= (CS8 | CREAD);

and glibc tries to be "helpful" and notice that some of the settings
don't stick. For no good reason.

Now, I'm not saying that the kernel necessarily has to do the above
for pty's (it could just ignore the bits, and not set them to what
pty's actually do), but Linux has always done the above, so it's some
idiotic change in glibc that now causes problems.

Don't ask me why the glibc people decided to "improve" on tcsetattr() this way.

Funnily enough, I do *not* find this in the glibc sources for
tcsetattr (sysdeps/unix/sysv/linux/tcsetattr.c):

  https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/tcsetattr.c

so I wonder if this is some Fedora "feature".

             Linus