1============
2Introduction
3============
4
5The firmware API enables kernel code to request files required
6for functionality from userspace, the uses vary:
7
8* Microcode for CPU errata
9* Device driver firmware, required to be loaded onto device
10  microcontrollers
11* Device driver information data (calibration data, EEPROM overrides),
12  some of which can be completely optional.
13
14Types of firmware requests
15==========================
16
17There are two types of calls:
18
19* Synchronous
20* Asynchronous
21
22Which one you use vary depending on your requirements, the rule of thumb
23however is you should strive to use the asynchronous APIs unless you also
24are already using asynchronous initialization mechanisms which will not
25stall or delay boot. Even if loading firmware does not take a lot of time
26processing firmware might, and this can still delay boot or initialization,
27as such mechanisms such as asynchronous probe can help supplement drivers.
28