I wrote a simple stream driver to learn device drivers, in that i am just having DLLEntry, Init and DeInit functions and also I have exported all the functions in a .def file .
I also added the registry settings for the driver in HKLM/Drivers/Sample.
I wrote a application to test its working, where i called ActivateDeviceEx with the following path .
My DLLEntry function is getting called, but Init function is not getting called. I am using RETAILMSG macros to print the debug information.
I also have seen the post 1 where he is also facing the same issue
But i dont understood what we have to do for it to work...
The fact that DllEntry gets called but Init does not hints at an issue with the function exports. A stream driver must export at least the following:
Init
Deinit
Open
Close
Read
Write
Seek
IOControl
Also, unless the Flags value in the registry includes DEVFLAGS_NAKEDENTRIES, each function must be prefixed with the device name, so if the driver supports, say, an XYZ device, the functions must be named XYZ_Init, XYZ_Deinit, etc.
Related
I am building a project and I have the board stm nucleo_l496zg. All i want to do is to use the drivers from the board in order to communicate the board after west flash with minicom, it is a simple string transfer and response program. I am building this project with zephyr and my issue is that I cant use the functions tty_init , tty_read and tty_set_rx_buf despite that I use the proper include " #include <console/tty.h> ". The compiler returns an undefined reference to thoose three functions but in my program I am using another one function from tty.h header which is tty_set_timeout but at this function it doesnt say nothing. Though I notiched in that in here(documentation of tty.h) tty_Set_timeout is the only function that has something inside. I cant understand why I am getting that please if someone can help me let me know !
I had the same problem and I solve it by adding those lines to my .conf file:
CONFIG_SERIAL=y
CONFIG_STDOUT_CONSOLE=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_CONSOLE_SUBSYS=y
CONFIG_CONSOLE_GETCHAR=y
And don't forget to mention the file (.conf file) also in your CMakeList.txt file:
set(CONF_FILE ***.conf)
Hope that it will work with you as well
I've written a character device driver that, I believe, should work.
I want to test the read/write functions. On another stack overflow question, apparently this can be done by writing to the device file in /dev and echoing the output.
I don't understand how this works:
When I load up my device driver by allocating a major number and calling mknod to create the file, is the file "open"? If it isn't open, then reading/writing shouldn't work like that from the command line, or so I thought?
What state is the device driver in when it has been initialized in /proc/devices and a file created in /dev?
Does this initialization need to happen before attempting to open the device file in a c program?
These answer are extremely difficult to find online, and many resources are outdated. Thanks
One good resource is Linux device driver. A shorter and simpler explanation can be found here.
When you create a file driver, you will implement some functions among file operations (fops):
open
close
read
write
seek
...
Not all function have to be implemented. If write is not implemented for instance, your device won't support writting.
When I load up my device driver by allocating a major number and calling mknod to create the file, is the file "open"?
When the /dev file is created, your module is only inited. A function like init_module is called
When the file is removed, your module is deinited. A function like module_cleanup is called.
What state is the device driver in when it has been initialized in /proc/devices and a file created in /dev?
In that case, the module is inited, the file are not open.
If it isn't open, then reading/writing shouldn't work like that from the command line, or so I thought?
When you read a file from command line, the file is open, read then closed, as a user, you don't have to care to open/close file explicitly.
Things are different if you are a C programmer, in that case, you explicitly have to open, read, close the files.
You can check that adding traces in your kernel code (using printk to print some info to kernel console, reading it with dmesg) or using strace that will trace the system calls.
Does this initialization need to happen before attempting to open the device file in a c program?
Let's resume:
The first function called will be module_init before it's called, the file doesnot exist in /dev
The last function called will be module_cleanup after it's called, the file doesnot exist in /dev
between init and cleanup, you can call the different open, close, read and write function.
Generally read/write are called between open and close.
How to implement this example in kernel driver?
I looked in 'cdev'. but, the result is not convincing for this function using this example struct.
For example:
dev/test/on // this function is change status in test module
dev/test/changed "hello" // this function is change char value
I Looked "cdev" and some github. But, it is "/dev/test" one file.
I found "sysfs"! Using this lib i can implement this example.
https://www.kernel.org/doc/Documentation/filesystems/sysfs.txt
I have successfully taken bio-metric prints and posted to the node server using the futronic sdk. I want to be able to use this library likewise for matching in the server because that's where the bio-metric prints for all users are stored. I stubbled upon the node-ffi library that helps define equivalent C functions that I have exported and compiled it down to a .dll file.
Now the challenge here is that I have tried to port the ftrAnsiSDK functions but the ftrScanAPI.dll and the ftrAnsiSDK.dll file could not be compiled together. It gives this error:
...collect2.exe [Error] ld returned 5 exit status
When I compile and export the functions that are not dependent on these two libraries, my code works fine and the functions are easily exported and used in the node server. Please can any one give me a hint?
Here is the link to the repo. It consists of the lib and .dll library that is been used.
For the server code here is a snippet of what I am trying to achieve:
var libm = ffi.Library('lib/visystem', {
'HelloWorld': [ 'void', [] ],
'PrintErrorMessage': [ 'void', ['int'] ],
'CaprureImage': [ 'int', ['int','int','int'] ]});
The HelloWord and PrintErrorMessages are methods that I used as a test case to ensure the functions are being exported before I proceeded to the main functions (you can see the function definition in from the code in the repo.. ) that depends on the futronic lin and sdk.
I am currently using a 64-bit operation system and I installed the same program on a 32-bit machine to be sure, but it still did not compile and export the function. The code editor I am using is Dev++C.
Can anyone help or even give me hint on how to achieve this goal?
As a disclaimer, I'm not familiar with the Dev-C++ IDE or MinGW development.
However, after a cursory look at your github repo, according to your libvisystem.def file, it appears that the only functions that are exported by your DLL are:
HelloWorld
PrintErrorMessage
ReadTemplateFile
SaveBmpFile
SaveTemplateFile
This is also confirmed when looking at the libvisystem.a library header:
So you should probably start by manually add the rest of the exported functions in your dll.h to the def file, in a similar manner to the ones that are already there, and see if that changes anything.
NOTE:
I'm not sure whether the __declspec(dllexport) directive is ignored by the Dev-C++ compiler/linker and it uses the def file instead. Perhaps others on SO have an idea.
I'm running linux kernel no. 2.6.15.51 on a ubuntu system.
I created a custom system call and added it to the kernel (containing a struct), compiled, and booted into the new kernel. Now I'm trying to create a c file that calls that system call (for testing purposes). Because I have a struct declared in my system call file, I am including the header in my test file so I can use that same struct. However, when I try including my system call file (which makes a call to access_ok() method), I get an error saying asm/uaccess.h (the file where access_ok() is declared) does not exist. Any ideas why I could be having this problem? Thank you!