The write call back function allows a userland process to write data to the kernel, so it has some kind of control over the kernel. The write function should have the following format:
The write function should read count
bytes at maximum from the buffer
. Note
that the buffer
doesn't live in the
kernel's memory space, so it should first be copied to kernel
space with copy_from_user
. The
file
parameter is usually
ignored. Section 3.3 shows how to use the
data
parameter.
Again, Chapter 5 shows how to use this call back function.