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- ============
- Introduction
- ============
- The firmware API enables kernel code to request files required
- for functionality from userspace, the uses vary:
- * Microcode for CPU errata
- * Device driver firmware, required to be loaded onto device
- microcontrollers
- * Device driver information data (calibration data, EEPROM overrides),
- some of which can be completely optional.
- Types of firmware requests
- ==========================
- There are two types of calls:
- * Synchronous
- * Asynchronous
- Which one you use vary depending on your requirements, the rule of thumb
- however is you should strive to use the asynchronous APIs unless you also
- are already using asynchronous initialization mechanisms which will not
- stall or delay boot. Even if loading firmware does not take a lot of time
- processing firmware might, and this can still delay boot or initialization,
- as such mechanisms such as asynchronous probe can help supplement drivers.
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