Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/Documentation/driver-api/firmware/built-in-fw.rst b/Documentation/driver-api/firmware/built-in-fw.rst
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+=================
+Built-in firmware
+=================
+
+Firmware can be built-in to the kernel, this means building the firmware
+into vmlinux directly, to enable avoiding having to look for firmware from
+the filesystem. Instead, firmware can be looked for inside the kernel
+directly. You can enable built-in firmware using the kernel configuration
+options:
+
+  * CONFIG_EXTRA_FIRMWARE
+  * CONFIG_EXTRA_FIRMWARE_DIR
+
+There are a few reasons why you might want to consider building your firmware
+into the kernel with CONFIG_EXTRA_FIRMWARE:
+
+* Speed
+* Firmware is needed for accessing the boot device, and the user doesn't
+  want to stuff the firmware into the boot initramfs.
+
+Even if you have these needs there are a few reasons why you may not be
+able to make use of built-in firmware:
+
+* Legalese - firmware is non-GPL compatible
+* Some firmware may be optional
+* Firmware upgrades are possible, therefore a new firmware would implicate
+  a complete kernel rebuild.
+* Some firmware files may be really large in size. The remote-proc subsystem
+  is an example subsystem which deals with these sorts of firmware
+* The firmware may need to be scraped out from some device specific location
+  dynamically, an example is calibration data for for some WiFi chipsets. This
+  calibration data can be unique per sold device.
+