# Core (various)
# File systems
Btrfs  
OverlayFS  
XFS  
ext4  
Ceph  
FUSE  
GFS2  
EROFS  
KSMBD  
NFS  
TMPFS  
# Memory management
# Block layer
# BPF
# Tracing, perf
# Virtualization
# Cryptography
# Security
# Networking
# Architectures
ARM  
x86  
DMA engines  
LoongArch  
RISC-V  
PowerPC  
PA-RISC  
S390  
# Drivers  
Graphics  
Storage  
Drivers in the Staging area  
Bluetooth  
Networking  
Audio  
Tablets, touch screens, keyboards, mouses  
TV tuners, webcams, video capturers  
Serial Peripheral Interface (SPI)  
Serial  
Voltage, current regulators, power capping, power supply
Watchdog  
Real Time Clock (RTC)  
FRU Support Interface (FSI)  
Clock  
Multi Media Card (MMC)  
Hardware monitoring (hwmon)  
Inter-Integrated Circuit (I2C + I3C)  
Industrial I/O (iio)  
General Purpose I/O (gpio)  
Cryptography hardware acceleration  
Leds  
PHY ("physical layer" framework)  
PCI  
Universal Serial Bus  
IOMMU  
Pin Controllers (pinctrl)  
Power Management  
Memory Technology Devices (MTD)  
Various  
## else
mdadm