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Difference between revisions of "Userland"

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m (Fixed Wikipedia link to Android's SurfaceFlinger)
m (Corrections.)
 
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A '''userland''' is the system utilities that are not a part of the main kernel, but provide a base system. The term userland (or user space) refers to all code that runs outside the operating system's kernel. Userland usually refers to the various programs and libraries that the operating system uses to interact with the kernel: software that performs input/output, manipulates file system objects, application software etc.
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A '''userland''' is the system utilities that are not a part of the kernel, but provide a base system. The term userland (or user space) refers to all code that runs outside the operating system's kernel. Userland usually refers to the various programs and libraries that the operating system uses to interact with the kernel: software that performs input/output, manipulates file system objects, application software etc.
  
 
{| class="wikitable"
 
{| class="wikitable"
|+ Various layers within Linux, also showing separation between the [[userland]] and [[wikipedia:kernel space|kernel space]]
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|+ Various layers within */Linux, also showing separation between the [[userland]] and [[wikipedia:kernel space|kernel space]]
 
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|-
 
! rowspan=3 style="width: 10%" | User mode
 
! rowspan=3 style="width: 10%" | User mode
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! rowspan=3 style="width: 10%" | Kernel mode
 
! rowspan=3 style="width: 10%" | Kernel mode
| rowspan=3 style="width: 10%" | '''[[Linux (kernel) | Linux kernel]]'''
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| rowspan=3 style="width: 10%" | '''[[Linux (kernel) | Linux]]'''
| colspan=5 style="width: 80%; background-color: #ffb7b7;" |{{ic|[[wikipedia:stat (system call)|stat]]}}, {{ic|[[wikipedia:splice (system call)|splice]]}}, {{ic|[[wikipedia:dup (system call)|dup]]}}, {{ic|[[wikipedia:read (system call)|read]]}}, {{ic|[[wikipedia:open (system call)|open]]}}, {{ic|[[wikipedia:ioctl|ioctl]]}}, {{ic|[[wikipedia:write (system call)|write]]}}, {{ic|[[wikipedia:mmap|mmap]]}}, {{ic|[[wikipedia:close (system call)|close]]}}, {{ic|[[wikipedia:exit (system call)|exit]]}}, etc. (about 380 system calls)<br>The Linux kernel [[wikipedia:System call|System Call Interface]] (SCI, aims to be [[POSIX]]/[[wikipedia:Single UNIX Specification|SUS]]-compatible)
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| colspan=5 style="width: 80%; background-color: #ffb7b7;" |{{ic|[[wikipedia:stat (system call)|stat]]}}, {{ic|[[wikipedia:splice (system call)|splice]]}}, {{ic|[[wikipedia:dup (system call)|dup]]}}, {{ic|[[wikipedia:read (system call)|read]]}}, {{ic|[[wikipedia:open (system call)|open]]}}, {{ic|[[wikipedia:ioctl|ioctl]]}}, {{ic|[[wikipedia:write (system call)|write]]}}, {{ic|[[wikipedia:mmap|mmap]]}}, {{ic|[[wikipedia:close (system call)|close]]}}, {{ic|[[wikipedia:exit (system call)|exit]]}}, etc. (about 380 system calls)<br>The Linux [[wikipedia:System call|System Call Interface]] (SCI, aims to be [[POSIX]]/[[wikipedia:Single UNIX Specification|SUS]]-compatible)
 
|- style="background-color: #ffb7b7;"
 
|- style="background-color: #ffb7b7;"
 
| style="width: 18%;" | [[wikipedia:Scheduling (computing)|Process scheduling]]<br>subsystem
 
| style="width: 18%;" | [[wikipedia:Scheduling (computing)|Process scheduling]]<br>subsystem

Latest revision as of 07:01, 9 May 2022

A userland is the system utilities that are not a part of the kernel, but provide a base system. The term userland (or user space) refers to all code that runs outside the operating system's kernel. Userland usually refers to the various programs and libraries that the operating system uses to interact with the kernel: software that performs input/output, manipulates file system objects, application software etc.

Various layers within */Linux, also showing separation between the userland and kernel space
User mode User applications For example, bash, LibreOffice, OpenOffice, Blender, 0 A.D., Mozilla Firefox, etc.
Low-level system components: System daemons:
systemd, runit, logind, networkd, soundd, ...
Windowing system:
X11, Wayland, Mir, SurfaceFlinger (Android)
Other libraries:
GTK+, Qt, EFL, SDL, SFML, FLTK, GNUstep, etc.
Graphics:
Mesa, AMD Catalyst, ...
C standard library open(), exec(), sbrk(), socket(), fopen(), calloc(), ... (up to 2000 subroutines)
glibc aims to be POSIX/SUS-compatible, uClibc targets embedded systems, bionic written for Android, etc.
Kernel mode Linux stat, splice, dup, read, open, ioctl, write, mmap, close, exit, etc. (about 380 system calls)
The Linux System Call Interface (SCI, aims to be POSIX/SUS-compatible)
Process scheduling
subsystem
IPC
subsystem
Memory management
subsystem
Virtual files
subsystem
Network
subsystem
Other components: ALSA, DRI, evdev, LVM, device mapper, Linux Network Scheduler, Netfilter
Linux Security Modules: SELinux, TOMOYO, AppArmor, Smack
Hardware (CPU, main memory, data storage devices, etc.)