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1=================2Built-in firmware3=================4 5Firmware can be built-in to the kernel, this means building the firmware6into vmlinux directly, to enable avoiding having to look for firmware from7the filesystem. Instead, firmware can be looked for inside the kernel8directly. You can enable built-in firmware using the kernel configuration9options:10 11 * CONFIG_EXTRA_FIRMWARE12 * CONFIG_EXTRA_FIRMWARE_DIR13 14There are a few reasons why you might want to consider building your firmware15into the kernel with CONFIG_EXTRA_FIRMWARE:16 17* Speed18* Firmware is needed for accessing the boot device, and the user doesn't19 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 be22able to make use of built-in firmware:23 24* Legalese - firmware is non-GPL compatible25* Some firmware may be optional26* Firmware upgrades are possible, therefore a new firmware would implicate27 a complete kernel rebuild.28* Some firmware files may be really large in size. The remote-proc subsystem29 is an example subsystem which deals with these sorts of firmware30* The firmware may need to be scraped out from some device specific location31 dynamically, an example is calibration data for some WiFi chipsets. This32 calibration data can be unique per sold device.33 34