Remove the redundant 'kmod' installation since it is already
installed earlier. Also replace the hardcoded kernel version
with 'uname -r' to improve portability and compatibility with
modern Linux distributions.
Update outdated /dev/hda[1-3] device file example to /dev/sda[1-3]
to match modern Linux systems. Adjust major number from 3 to 8
accordingly and remove outdated reference to IDE devices.
Use GPIO to control LED on/off and add related GPIO knowledge.
Test detail:
- Tested on Raspberry Pi 5B with Raspberry Pi OS (Debian 12, Linux
version 6.12.1-v8-16k+)
- Verify that LED example compiles and loads successfully
- Verify that LED turns on and off sucessfully
For x86 architecture, the system call table cannot be used to invoke
a system call after commit 1e3ad78 since v6.9. This commit has been
backported to long term stable kernels, like v5.15.154+, v6.1.85+,
v6.6.26+ and v6.8.5+[1]. In this case, thanks to Kprobes, a hook can be
used instead on the system call entry to intercept the system call.
[1] https://stackoverflow.com/a/78607015
Co-authored-by: Hao Dong <hao.dong.work@outlook.com>
Add sudo to commands in Chapter 8 for example module interaction.
The "myvariables" in the module are set with 0660 permissions
via __ATTR(), preventing direct user access.
Options to fix this:
1. Instruct users to use 'sudo' to read/write files.
2. Relax the permission settings to 0666.
This commit adopts the sudo method to maintain security constraints.
7.4 The seq_file is missing the behavior that occurs when it
directly returns NULL after the start step.
Also, in the flowchart, the first decision where `return is NULL`
is `Yes` points to nothing, which is not defined in ISO 5807.
ISO 5807 section 10.3.1.2 states logic path of a decision,
"Each exit from a symbol be accompanied by the appropriate
condition values to show the logic path which it represents,
so that the conditions and the associated references are identified."
The behavior of pointing to nothing does not have associated
references and does not indicate the relation of this logic path.
Refs:
1. The Liunx Kernel Module Programming Guide
7.4 Manage /proc file with seq_file
2. ISO-5807-1985
Aquiring a spinlock makes the holder enter atomic context. Extra
attention is needed in atomic context. In particular, functions
that may sleep must not be used. Add this detail to the spinlock
section.
The past content in the crypto section lacks informative descriptions,
and there should be a proper procedure to demonstrate how Linux
cryptography works. Due to poor maintenance, let's drop the section.
The SA_xxx flags has been removed for years. Nowadays the kernel uses
the IRQF_xxx flags to specify IRQ behaviors. Adjust the descriptions
in the book accordingly.
In Debian, the name syscall conflicts with this patch:
in debian kernel source tree:
debian/patches/features/x86/x86-make-x32-syscall-support-conditional.patch
mailing list url:
https://lore.kernel.org/lkml/1415245982.3398.53.camel@decadent.org.uk/T/#u
which introduces a parameter named syscall.x32. So change our name.
The word 'defator' is unable to be found in a lexicon. Change the word
'defator' with 'drawbacks' which should imply the negative meaning intended
in the sentence.
Two struct completion(s) are encapsulated within another 'struct machine'.
Simplify the code by removing the outer struct and let the struct
completion(s) be self-standing.
Update description in tex to match code.
