introduction.rst (935B)
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.