The proc_ops structure is defined in <include/linux/proc_fs.h> since
Linux v5.6+.
In older kernels, file_operations structure is used for custom hooks in
/proc file system. However, it contains some members that are unnecessary
in VFS, and every time VFS expands file_operations set, /proc code comes
bloated.
On the other hand, not only the space, but also some operations were
saved by this structure to improve its performance.
For the example module hello_5, the book showed the incorrect output
in corresponding with its execution results.
In addition, this patch changes from myintArray[2] = {-1, -1} to
myintArray[2] = {420, 420}, which help the readers distinguish from
the kernel messages.
This patch generates HTML files with "make4ht" in the "html" directory.
Known issues with "make4ht":
Running "make4ht -suf html5 -d html lkmpg.tex" will cause the following
flaws:
1. The layout was unsatisfying.
2. After parsing TeX, it stoped at "\tableofcontents" with errors.
3. Several unneeded files were generated.
4. No way to specify the destination filename for HTML generation.
Solutions/workaround:
1. Use customized configuration file "html.cfg" to specify the layout style.
2. Turn off the \tableofcontents section when using make4ht. However, this
results in the lack of table of contents in HTML. It can be fixed by
appending "\Configure{tableofcontents*}{chapter,section,subsection}"
to configuration file.
3. The build system removes the temporary files.
4. Use a symbolic link "index.html" to "lkmpg.html".
This patch enforces the assumption of using as a non-root user. That is,
it is necessary to specify sudo for the essential commands such as
insmod and rmmod. In addition, most command prompts should start with
$ (dollar sign).
