linux-kernel-architecture

Original：🇺🇸 English

Translated

Linux kernel architecture skill for subsystem overview. Use when navigating kernel source, understanding boot flow, initcalls, or major subsystems (VFS, scheduler, MM). Activates on queries about kernel architecture, boot process, initcall levels, subsystem layout, or where code lives in linux.git.

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Sourcemohitmishra786/low-level-dev-skills

Added on2026-08-20

NPX Install

npx skill4agent add mohitmishra786/low-level-dev-skills linux-kernel-architecture

SKILL.md Content

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Linux Kernel Architecture

Purpose

Provide a mental map of the Linux kernel: boot sequence, major subsystems, key data structures, and where to look in source — complementing

skills/kernel/kernel-internals

with architecture-level navigation for driver and subsystem work.

When to Use

First time exploring
```
linux.git
```
for a feature or bug
Understanding how boot reaches
```
init
```
and driver
```
probe
```
Tracing a syscall or interrupt through subsystems
Onboarding before
```
skills/kernel-dev/platform-device-model
```
or driver skills

Workflow

1. Boot flow (x86/ARM64 simplified)

firmware/UEFI
├── arch/*/boot — decompress kernel, early setup
├── start_kernel() — mm, scheduler, timers, IRQ subsys
├── rest_init() → kernel_init → run_init_process
└── userspace init (systemd)

Driver

module_init

/

device_initcall

run during

start_kernel

before init.

2. Major subsystems

Subsystem	Path (typical)	Key structs
Scheduler	`kernel/sched/`	`task_struct` , `sched_entity`
Memory	`mm/`	`struct page` , `mm_struct` , `vm_area_struct`
VFS	`fs/`	`inode` , `dentry` , `file` , `super_block`
Block	`block/`	`request_queue` , `gendisk`
Net	`net/`	`sk_buff` , `net_device`
Drivers	`drivers/`	`device` , `device_driver`
Syscalls	`kernel/` , `fs/` , `mm/`	`SYSCALL_DEFINE*`

3. Initcall levels

c

/* include/linux/init.h — order matters */
early_initcall → core_initcall → postcore_initcall
→ arch_initcall → subsys_initcall → fs_initcall
→ device_initcall → late_initcall

Platform drivers usually register at

subsys_initcall

or via

module_init

.

4. Finding code

bash

# Locate symbol
grep -rn "platform_driver_register" drivers/

# Trace config
./scripts/config --state CONFIG_FOO

# File hierarchy docs
ls Documentation/admin-guide/

5. Agent usage

/linux-kernel-architecture Where does page fault handling live and what calls it?

Common Problems

Symptom	Cause	Fix
Driver probes too early	Initcall vs DT ordering	Defer with `deferred_probe`
Symbol missing	Built as module	`modprobe` or built-in `CONFIG_*`
Wrong subsystem	Similar names in `drivers/`	Follow `struct bus_type`
Boot hang	Early printk disabled	`earlyprintk` , `initcall_debug`

Related Skills

```
skills/kernel/kernel-internals
```
— scheduler, SLUB, VFS depth

skills/kernel-dev/kernel-memory-management

— mm/ details

```
skills/kernel-dev/platform-device-model
```
— driver model
```
skills/kernel-dev/device-tree
```
— hardware description

skills/low-level-programming/linux-kernel-modules

— LKM basics