The following in tty0tty.c is wrong. It should be 3.8.

#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,7,0)
tty_port_destroy(&tport[i]);
#endif

Also, why isn't this function being called if tty_register_driver fails? The tty_port_destroy comment in tty_port.c is:

• When a port was initialized using tty_port_init, one has to destroy the
• port by this function. Either indirectly by using tty_port refcounting
• (tty_port_put) or directly if refcounting is not used.

Sorry if this is the wrong way to go about this, but is there any plans / chance for a CUSE module as opposed to a "standard" kernel module?

Hi,

i was success to create ebuild, install it and do some simple tests on my Funtoo with 4.9.18 kernel, then you can update the README about tested kernel versions.

For manage access rights i use simple udev rule in /lib/udev/rules.d/10-tty0tty.rules:

# set tty0tty devices permission
KERNEL=="tnt*" SUBSYSTEM=="tty", MODE="0660", GROUP="uucp"

IMO, you can describe to use udev rules, instead manually changing the the device files rights.

The TIOCMIWAIT ioctl is dangerously broken. Presently, it will oops when issued, since the wait queue it uses isn't initialized, but even if that were fixed, it would never return (unless interrupted), since the places that are supposed to trigger the wait queue never actually wake it up!

I'll be around with a patch set to fix.

Hello,

I followed the steps exactly for installation.
/pts/make works perfectly fine.

But /module/make throws the following error.
error: initialization of ‘int (*)(struct tty_struct )’ from incompatible pointer type ‘unsigned int ()(struct tty_struct *)’ [-Werror=incompatible-pointer-types]
603 | .write_room = tty0tty_write_room,
| ^~~~~~~~~~~~~~~~~~

I have ugraded the Kernal and build and also tried re installing them but the error remains the same

After git clone we are downloading a folder, not an archive. So no need to unzip it.

I am also getting same issues, below is the traceback, could you please check and tell where is the issue ?

===================================================================
waageesh@waageesh-Aspire-A715-75G:~/Downloads/Softwares/tty0tty$ hostnamectl
Static hostname: waageesh-Aspire-A715-75G
Icon name: computer-laptop
Chassis: laptop
Machine ID: 7a93dcb479364111a24c53faca24ad60
Boot ID: f50dc5d4059f49ca9bcabbf3e677ea32
Operating System: Ubuntu 20.04.2 LTS
Kernel: Linux 5.8.0-48-generic
Architecture: x86-64

===================================================================

Thank you for this works. Please find below the steps I followed to install that on Fedora 27:

su -c 'dnf install kernel-devel'
sudo dnf install elfutils-libelf-devel
git clone https://github.com/freemed/tty0tty
cd tty0tty/module
make
(root) cp tty0tty.ko /lib/modules/$(uname -r)/kernel/drivers/misc/
(root) depmod
(root) modprobe tty0tty
(root) chmod 666 /dev/tnt*
ls -la /dev/tnt*

Fedora documentation to know more about requirements to build kernel modules: https://fedoraproject.org/wiki/Building_a_custom_kernel#Building_Only_Kernel_Modules_.28Out_Of_Tree_Modules.29

ENOTTY received on Linux kernel 5.12.4-arch1-2

openat(AT_FDCWD, "/dev/tnt1", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_CLOEXEC) = 10
flock(10, LOCK_EX|LOCK_NB) = 0
ioctl(10, TIOCEXCL) = 0
ioctl(10, TCGETS, {B38400 -opost -isig -icanon -echo ...}) = 0
ioctl(10, TIOCMGET, [0]) = 0
ioctl(10, TCGETX, 0x55a071c56090) = -1 ENOTTY (Inappropriate ioctl for device)
close(10) = 0

Kernel: 6.2.0-25-generic x86_64
gcc: (Ubuntu 12.3.0-1ubuntu1~23.04) 12.3.0

After cloning, building module fails:

git clone https://github.com/freemed/tty0tty.git
cd tty0tty/module/
make
. . . 
tty0tty.c:608:24: error: initialization of ‘void (*)(struct tty_struct *, const struct ktermios *)’ from incompatible pointer type ‘void (*)(struct tty_struct *, struct ktermios *)’ [-Werror=incompatible-pointer-types]
  608 |         .set_termios = tty0tty_set_termios,

Changing line 291 from:

struct ktermios *old_termios)

to

const struct ktermios *old_termios)

resolved the error.

The issue is here.
This function now needs to return unsigned int instead of int to compile against kernel 5.14.

I can't run the emulator under 4.15.0-32-generic in Ubuntu 18.04. Here's what I tried:

cd modules
make
sudo cp tty0tty.ko /lib/modules/$(uname -r)/kernel/drivers/misc/
sudo depmod
sudo modprobe tty0tty # this fails with "modprobe: ERROR: could not insert 'tty0tty': Device or resource busy"

and there are no tnt* devices under /dev/.

This used to work under 4.15.0-29-generic, but not under 4.15.0-30-generic or 4.15.0-32-generic.

Could you please help me with this?

I have a scenario where the application connected to the other paired port can only read data at a certain rate (because it is passing it on to another slow hardware device). So I want to limit the number of bytes that can be written in one port, to ensure the other paired port's input data queue gets no bigger than, say, 64 bytes. So I want to modify tty0tty_write_room() function in the tty0tty module, so that it returns eg [64 – the number of bytes in the other paired port's input queue].

I'm trying to figure out how to get the number of bytes in the other paired port's input queue. It looks as though tty_insert_flip_string() is the way to write bytes into the other paired port's input queue. But I can't see a function that will give me a count of bytes in the other paired port's input queue. Do you have any advice on this?

Latest commit tested for newer and older (w.r.t. KERNEL_VERSION(5, 14, 0)) versions and found back/forward compatibility issues for 4 lines below:

After patching lines as below, working older and newer kernel versions.

1. This is a back compatibility issue

=> Now:

=> Patch for back compatiblity;

#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 14, 0)
	tty0tty_tty_driver = tty_alloc_driver(2 * pairs, 0);
#else
	tty0tty_tty_driver = alloc_tty_driver(2*pairs);
#endif

2. This is a back compatibility issue

=> Now:

=> Patch for back compatiblity;

#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 14, 0)
	tty_driver_kref_put(tty0tty_tty_driver);
#else
	put_tty_driver(tty0tty_tty_driver);
#endif	

3.This is a back compatibility issue, but this is also not working for newer versions ('tty0tty_write' could return negative value, but assumed that it should return non-negative value)

=> Now:

=> Patch for back compatiblity & for newer ( > KERNEL_VERSION(5, 14, 0)) kernel versions,

int retval = -EINVAL;

4. This is a back compatibility issue, ('tty0tty_write_room' function now returns (for this line) non-negative for older versions, but should return non-negative for newer kernels, and negative for older versions.)

=> Now:

	int room = 0;

	if (!tty0tty)
		return -ENODEV;

=> Patch for older & newer ( > KERNEL_VERSION(5, 14, 0)) kernel versions,

#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 14, 0)
	int room = -EINVAL;
#else
	int room = 0;
#endif	

	if (!tty0tty) {
#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 14, 0)
            room = -ENODEV
#endif
            return room;
        }

How can we get it running in wsl2??

Hi,

I am using module with QSerialPort at Qt 5.12 on Manjaro.

After open, there is no error. But after write(), QSerialPort returns Resource temporarily unavailable error, and closes.

I am opening /dev/tnt0 and there is no opened on the other side. I need to write without connection. Trying to implement a virtual electronics device. There is a gui which tries to connect with timer on the other side.

After some search, Resource temporarily unavailable is related with EAGAIN, I think. But I couldn't find at module c file. Specially write function.

I tried with kernels; 5.10, 5.15, 5.19.

At some trials my virtual device and gui connected. But not all the times.

How can I fix this error ?

• Manjaro PKGBUILD file; https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=tty0tty-dkms-git
• Related Qt question; https://forum.qt.io/topic/59425/solved-qserialport-strange-difference-from-win-to-linux/4
• QSerialPort docs ; https://doc.qt.io/qt-5/qserialport.html#details
• Params; Baud=38400, DataBits=Data8, Parity=NoParity, SoptBits=OneStop, Flow=NoFlowControl

Edit1;

• Complete the question.
• Added tried kernel versions.

Hi,
On the last Linux Mint 19.3 with Kernel 5.0.0-37, it is impossible to install tty0tty.
I get this error : modprobe: ERROR: could not insert 'tty0tty': Device or resource busy

Please help me because without tty0tty, I can't make my educational project with students. I'm a radioamateur and I really need it for Doppler correction with my radio YAESU FT-847.

tty0tty is a part of a very complex software bundle since many years to enable the lack of my radio to be controlled in TX and RX on same frequencies range for ISS communications. I really really need it.

Have a look at my website : https://f4bpp.com/articles.php?lng=en&pg=55&tconfig=0

Thanks for your help.

David.

Good day to you

I am trying to compile tty0tty on a BeagleBone Black

I am experiencing the following problem when trying to compile
Could you please assist?
Thank you in advance
Anton
root@arm:/tty0tty/tty0tty-1.2/module# make
make -C /lib/modules/4.4.84-ti-r120/build M=/root/tty0tty/tty0tty-1.2/module modules
make[1]: *** /lib/modules/4.4.84-ti-r120/build: No such file or directory. Stop.
Makefile:26: recipe for target 'default' failed
make: *** [default] Error 2
root@arm:/tty0tty/tty0tty-1.2/module# cd tty0tty-1.2/module

Second attempt

root@arm:/tty0tty-1.2/module# make
make -C /lib/modules/4.4.84-ti-r120/build M=/root/tty0tty-1.2/module modules
make[1]: *** /lib/modules/4.4.84-ti-r120/build: No such file or directory. Stop.
Makefile:26: recipe for target 'default' failed
make: *** [default] Error 2
root@arm:/tty0tty-1.2/module#

Hi,
I have follow all installation step without problems, but at the moment of load the module on kernel I receive this error:

modprobe: ERROR: could not insert 'tty0tty': Device or resource busy

I have found another user that have test the same issue nvidia forum but the same solution doesn't work for me! I have try many other minor number but the problem remains.
Some suggestions?

Thanks

The code needs to be updated for Linux >= 6.6:

Here is a patch that adds support for Linux >= 6.6 (needs to have the patch for Linux >= 6.1 also be added separately):

linux-6.6-fixup.patch.txt:

diff -rU1 tty0tty.linux-6.1-fixed/module/tty0tty.c tty0tty/module/tty0tty.c
--- tty0tty.linux-6.1-fixed/module/tty0tty.c	2024-01-11 20:13:27.739146823 +0100
+++ tty0tty/module/tty0tty.c	2024-01-11 20:14:35.892478188 +0100
@@ -212,4 +212,9 @@
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(6,6,0)
+static ssize_t tty0tty_write(struct tty_struct *tty, const unsigned char *buffer,
+			 size_t count)
+#else
 static int tty0tty_write(struct tty_struct *tty, const unsigned char *buffer,
 			 int count)
+#endif
 {

(Authorship goes to @ozz from Arch User Repository.)

linux-6.1-fixup.patch.txt:

diff -rU1 tty0tty.org/module/tty0tty.c tty0tty/module/tty0tty.c
--- tty0tty.org/module/tty0tty.c	2024-01-11 20:08:54.922488036 +0100
+++ tty0tty/module/tty0tty.c	2024-01-11 20:10:36.829151760 +0100
@@ -290,2 +290,5 @@
 static void tty0tty_set_termios(struct tty_struct *tty,
+				#if LINUX_VERSION_CODE >= KERNEL_VERSION(6,1,0)
+					const
+				#endif
 				struct ktermios *old_termios)

(Note that tabulars are used!, copy & paste might transform them to whitespace which will break applying the patches.)

Regards!

The original project isn't dead--it looks as though it's had further work done on it. It could be good to merge it in.

module/tty0tty.c:610:18: erreur: initialisation de « ssize_t (*)(struct tty_struct *, const u8 *, size_t) » {alias « long int (*)(struct 
tty_struct *, const unsigned char *, long unsigned int) »} depuis le type pointeur « int (*)(struct tty_struct *, const unsigned 
char *, int) » qui est incompatible [-Werror=incompatible-pointer-types]
  610 |         .write = tty0tty_write,
      |                  ^~~~~~~~~~~~~

I got this error when doing make in /module/

Hi,
I installed the tool and it seemed to work.
I don't know what happened, but suddenly I have following problem:

$ sudo depmod
$ sudo modprobe tty0tty
$ ls /dev/tnt*
/dev/tnt0  /dev/tnt2  /dev/tnt4  /dev/tnt6
/dev/tnt1  /dev/tnt3  /dev/tnt5  /dev/tnt7
$ sudo chmod 666 /dev/tnt*
$ echo test > /dev/tnt0
bash: echo: write error: Invalid argument

This error appears when I try to write in the terminal, or open normally. After the error, the port closes. Writing to a physical com port works without problems.
What is wrong?
Best,
Jan

Thank you for this code, I've been using it for about a year, however, when building the module for my current kernel, I met with fail.
system: 4.11.7-1-ARCH #1 SMP PREEMPT Sat Jun 24 22:22:46 CDT 2017 x86_64 GNU/Linux
Error:
tty0tty-1.2/module/tty0tty.c:524:8: error: implicit declaration of function ‘signal_pending’; did you mean ‘timer_pending’? [-Werror=implicit-function-declaration]
if (signal_pending(current))
^~~~~~~~~~~~~~
timer_pending
cc1: some warnings being treated as errors

After a solid two minutes of effort, the fix:
Add to includes in tty0tty.c:
#include <linux/sched/signal.h>

Thank you.

LSB Version: 1.4
Distributor ID: Arch
Description: Arch Linux
Release: rolling
Codename: n/a

make -C /lib/modules/5.13.9-arch1-1/build M=/home/andy/Documents/makedeb/tty0tty-1.3/module modules
make[1]: Entering directory '/usr/lib/modules/5.13.9-arch1-1/build'
CC [M] /home/andy/Documents/makedeb/tty0tty-1.3/module/tty0tty.o
/home/andy/Documents/makedeb/tty0tty-1.3/module/tty0tty.c: In function ‘tty0tty_ioctl_tcsets’:
/home/andy/Documents/makedeb/tty0tty-1.3/module/tty0tty.c:646:22: error: implicit declaration of function ‘tty_check_change’ [-Werror=implicit-function-declaration]
646 | int retval = tty_check_change(tty);
| ^~~~~~~~~~~~~~~~
/home/andy/Documents/makedeb/tty0tty-1.3/module/tty0tty.c:671:32: error: implicit declaration of function ‘tty_termios_input_baud_rate’; did you mean ‘tty_termios_encode_baud_rate’? [-Werror=implicit-function-declaration]
671 | tmp_termios.c_ispeed = tty_termios_input_baud_rate(&tmp_termios);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
| tty_termios_encode_baud_rate
cc1: some warnings being treated as errors
make[2]: *** [scripts/Makefile.build:273: /home/andy/Documents/makedeb/tty0tty-1.3/module/tty0tty.o] Error 1
make[1]: *** [Makefile:1853: /home/andy/Documents/makedeb/tty0tty-1.3/module] Error 2
make[1]: Leaving directory '/usr/lib/modules/5.13.9-arch1-1/build'
make: *** [Makefile:29: default] Error 2

After Arch Linux got an update to Linux 6.1.1, tty0tty does not compile anymore.

make[1]: Entering directory '/home/user/work/src/tty0tty-/module'
make -C /lib/modules/6.1.1-arch1-1/build M=/home/user/work/src/tty0tty-/module modules
make[2]: Entering directory '/usr/lib/modules/6.1.1-arch1-1/build'
  CC [M]  /home/user/work/src/tty0tty-/module/tty0tty.o
/home/user/work/src/tty0tty-/module/tty0tty.c:608:24: error: initialization of ‘void (*)(struct tty_struct *, const struct ktermios *)’ from incompatible pointer type ‘void (*)(struct tty_struct *, struct ktermios *)’ [-Werror=incompatible-pointer-types]
  608 |         .set_termios = tty0tty_set_termios,
      |                        ^~~~~~~~~~~~~~~~~~~
/home/user/work/src/tty0tty-/module/tty0tty.c:608:24: note: (near initialization for ‘serial_ops.set_termios’)
cc1: some warnings being treated as errors
make[3]: *** [scripts/Makefile.build:250: /home/user/work/src/tty0tty-/module/tty0tty.o] Error 1