1=================
2Built-in firmware
3=================
4
5Firmware can be built-in to the kernel, this means building the firmware
6into vmlinux directly, to enable avoiding having to look for firmware from
7the filesystem. Instead, firmware can be looked for inside the kernel
8directly. You can enable built-in firmware using the kernel configuration
9options:
10
11  * CONFIG_EXTRA_FIRMWARE
12  * CONFIG_EXTRA_FIRMWARE_DIR
13
14There are a few reasons why you might want to consider building your firmware
15into the kernel with CONFIG_EXTRA_FIRMWARE:
16
17* Speed
18* Firmware is needed for accessing the boot device, and the user doesn't
19  want to stuff the firmware into the boot initramfs.
20
21Even if you have these needs there are a few reasons why you may not be
22able to make use of built-in firmware:
23
24* Legalese - firmware is non-GPL compatible
25* Some firmware may be optional
26* Firmware upgrades are possible, therefore a new firmware would implicate
27  a complete kernel rebuild.
28* Some firmware files may be really large in size. The remote-proc subsystem
29  is an example subsystem which deals with these sorts of firmware
30* The firmware may need to be scraped out from some device specific location
31  dynamically, an example is calibration data for for some WiFi chipsets. This
32  calibration data can be unique per sold device.
33
34