Executable structure

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Dynamic linking

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File system

A file is an abstraction of persistent storage, hiding details of storage devices: protocol, allocation, etc.

• A disk may contain multiple partitions, the file system lives on the partition basis.
• Anything containing a file system is known as a volume. Volumes can span multiple disks.

Disk structure

• Boot area
• File system control block (or superblock): filesystem type, #blocks, metadata layout
• Array of file control block: permission, ownership, etc. of each file
• (optional) Free space map
• Additional structures stored in memory:
  • In-memory partition tables
  • Cached directory information
  • System-wide in-core file state
  • Process open-file tables

Bootstrapping

1. Ground zero:
2. BIOS: mini real OS
   1. Stored in mostly-read-only memory (nowadays flash memory, previously: EEPROM, EPROM, PROM)
   2. Load the actual OS
   3. Configures hardware details: RAM refresh rate (bus speed), password protection, Boot-device order, etc.

I/O devices

Memory-mapped IO vs port-mapped IO…