On 30/09/20 11:19 pm, Greg KH wrote:
On Wed, Sep 30, 2020 at 10:32:05PM +0530, ymdatta wrote:
I want to write in this file, how should i be accessing the space created from previous function call.
That's not what "size" means here. "size" just sets the value that you see if you look at the directory for that debugfs file (or stat() it).
Didn't realize this. Why do we need this then? What does this 'size' help in achieving (or) where is this used?
debugfs is a virtual filesystem, there is no "backing store" or place to put your data in it. It is there so that you can write code that can handle open/read/write/close to happen on a file, and your code will provide the data to userspace directly.
The simplest way to create a debugfs file is to just point it at a variable, and then you can change the variable value in the kernel, and userspace reading from the file will see whatever the value is at that point in time.
This clears up a lot of my doubts. Thanks! ymdatta.