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The Linux System (Memory management (Virtual memory (Memory region backed…

- - - - made up of physically contiguous pages
      - three states
        
        Full
        
        Empty
        
        Partial
  - - - demand zero
    - - Policy algorithm
        
        Decides which pages to write out to disk and when to write them
  - - - The binary loader does not load a binary into main memory
      - Pages are mapped into regions of virtual memory
    - - Position-independent code
        
        Can run anywhere in memory
- - - - The core of linux
        
        Handles
        
        IPC
        
        Different builds
        
        Dev
        
        Prod
  - - - improved quality
  - - - GNU C Comolier
  - - - Authors have waived copytight
      - source must be redistributed
- - - - Preemptive, priority based
      - two priority ranges
        
        real-time
        
        nice value
      - No time slice
        
        all porocesses are alloted a proportion of processing time
  - - - Different processes on separate processors
      - BKL
        
        big kernel lock
        
        allows multiple kernel processes
- - - - Each process has unique id PID
      - Credentials
        
        Associated user id
      - Personality
      - Namespace
        
        Each process is associated with a view of fs hierarchy
  - - - List of command line arguments
    - - List of name value pairs
        
        Associate
        
        Environment variables
        
        Textual values
  - - - information of the scheduler
- - - - Inode object
      - File opbject
      - Superblock object
      - Dentry object
  - - - Extended file system
        
        seconde extended ext2
        
        third extended ext3
        
        fourth extended ext4
      - Allocation policy
        
        Partitioned into multiple segements
        
        Block groups
        
        Cylinder groups
  - - - once written it is commited
  - - - Provides an interface
      - Process file system
        
        stored anywhere
        
        Computed on demand
- - - - Modules can be loaded and communicate with the rest of the kernel
      - Two loading sections
        
        Management of section of module code in kernel memory
        
        Handling of symbols that modules are allowed to reference
    - - Device drivers
      - File systems
      - Network protocols
      - Binary format
    - - Prevents clashing over access to hardware resources
      - prevents autoprobes
      - Resolves conflicts among multiple drivers
- - - - Maintains all important abstractions
    - - Standard set of functions
      - Made to interact with kernel
    - - Management task programs
- - - - Pipe allows children to inherit communication channel
- - - - A salt value is added
    - - Can be used by any system component that needs to authenticate
  - - - The process has user right or owner rights for said object
- - - - All devices that allow random access to blocks of data
      - Blocks are read and stored in buffers
      - Completely fair queueing
    - - Mice and keyboard, character devices are accessed serially
      - Line discipline
        
        Line interpreter for the information from the terminal device
    - - communication is indirect