How can I save data to a device file?
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I'm currently building a kernal module that creates a device under /dev and I want to store some data inside of the device file. However, every time I try to write to the device file, nothing is being saved to that specific file.
Currently, I've tried to use device_write/device_read with no luck since the data I'm writing does not save in the kernel space after running the userprogram again. I've also tried using ioctl calls from the user-program and using copy_from_user and copy_to_user but that also doesn't save any data.
linux linux-device-driver device-driver ioctl
asked Nov 9 at 6:31
Harsh Patel
1
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up vote
-2
down vote
favorite
I'm currently building a kernal module that creates a device under /dev and I want to store some data inside of the device file. However, every time I try to write to the device file, nothing is being saved to that specific file.
Currently, I've tried to use device_write/device_read with no luck since the data I'm writing does not save in the kernel space after running the userprogram again. I've also tried using ioctl calls from the user-program and using copy_from_user and copy_to_user but that also doesn't save any data.
linux linux-device-driver device-driver ioctl
asked Nov 9 at 6:31
Harsh Patel
1
1
How do you expect the data to be stored? A "device file" isn't a form of storage. Show us your code.
– duskwuff
Nov 9 at 7:32
add a comment |
up vote
-2
down vote
favorite
up vote
-2
down vote
favorite
I'm currently building a kernal module that creates a device under /dev and I want to store some data inside of the device file. However, every time I try to write to the device file, nothing is being saved to that specific file.
Currently, I've tried to use device_write/device_read with no luck since the data I'm writing does not save in the kernel space after running the userprogram again. I've also tried using ioctl calls from the user-program and using copy_from_user and copy_to_user but that also doesn't save any data.
linux linux-device-driver device-driver ioctl
asked Nov 9 at 6:31
Harsh Patel
1
I'm currently building a kernal module that creates a device under /dev and I want to store some data inside of the device file. However, every time I try to write to the device file, nothing is being saved to that specific file.
Currently, I've tried to use device_write/device_read with no luck since the data I'm writing does not save in the kernel space after running the userprogram again. I've also tried using ioctl calls from the user-program and using copy_from_user and copy_to_user but that also doesn't save any data.
linux linux-device-driver device-driver ioctl
linux linux-device-driver device-driver ioctl
asked Nov 9 at 6:31
Harsh Patel
1
asked Nov 9 at 6:31
Harsh Patel
1
asked Nov 9 at 6:31
Harsh Patel
1
asked Nov 9 at 6:31
Harsh Patel
1
asked Nov 9 at 6:31
Harsh Patel
1
1
1
How do you expect the data to be stored? A "device file" isn't a form of storage. Show us your code.
– duskwuff
Nov 9 at 7:32
add a comment |
1
How do you expect the data to be stored? A "device file" isn't a form of storage. Show us your code.
– duskwuff
Nov 9 at 7:32
1
1
How do you expect the data to be stored? A "device file" isn't a form of storage. Show us your code.
– duskwuff
Nov 9 at 7:32
How do you expect the data to be stored? A "device file" isn't a form of storage. Show us your code.
– duskwuff
Nov 9 at 7:32
add a comment |
1 Answer
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0
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Just by creating a device node in /dev doesnt mean you have a device which can read/write. Its just a handle to talk to hardware from user space. If you are creating a driver for some block device SD/USB you need to refer the device specific framework.
If you are just creating a dummy device and want to implement read/write the you can just allocate some kernel memory in probe and in device_write, copy to that memory and in device_read, read the contents of the memory.
answered Nov 9 at 9:19
Prabhakar Lad
783158
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
Just by creating a device node in /dev doesnt mean you have a device which can read/write. Its just a handle to talk to hardware from user space. If you are creating a driver for some block device SD/USB you need to refer the device specific framework.
If you are just creating a dummy device and want to implement read/write the you can just allocate some kernel memory in probe and in device_write, copy to that memory and in device_read, read the contents of the memory.
answered Nov 9 at 9:19
Prabhakar Lad
783158
add a comment |
up vote
0
down vote
Just by creating a device node in /dev doesnt mean you have a device which can read/write. Its just a handle to talk to hardware from user space. If you are creating a driver for some block device SD/USB you need to refer the device specific framework.
If you are just creating a dummy device and want to implement read/write the you can just allocate some kernel memory in probe and in device_write, copy to that memory and in device_read, read the contents of the memory.
answered Nov 9 at 9:19
Prabhakar Lad
783158
add a comment |
up vote
0
down vote
up vote
0
down vote
Just by creating a device node in /dev doesnt mean you have a device which can read/write. Its just a handle to talk to hardware from user space. If you are creating a driver for some block device SD/USB you need to refer the device specific framework.
If you are just creating a dummy device and want to implement read/write the you can just allocate some kernel memory in probe and in device_write, copy to that memory and in device_read, read the contents of the memory.
answered Nov 9 at 9:19
Prabhakar Lad
783158
Just by creating a device node in /dev doesnt mean you have a device which can read/write. Its just a handle to talk to hardware from user space. If you are creating a driver for some block device SD/USB you need to refer the device specific framework.
If you are just creating a dummy device and want to implement read/write the you can just allocate some kernel memory in probe and in device_write, copy to that memory and in device_read, read the contents of the memory.
answered Nov 9 at 9:19
Prabhakar Lad
783158
answered Nov 9 at 9:19
Prabhakar Lad
783158
answered Nov 9 at 9:19
Prabhakar Lad
783158
answered Nov 9 at 9:19
Prabhakar Lad
783158
783158
add a comment |
add a comment |
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How do you expect the data to be stored? A "device file" isn't a form of storage. Show us your code.
– duskwuff
Nov 9 at 7:32