ref-manual: Add documentation for kernel-fitimage

This documents kernel-fitimage.bbclass as well as
the variables that are required to use the class
to create a FIT image.

(From yocto-docs rev: 3aeca3b342e5be92be562f6dea6b71390c31b636)

Signed-off-by: Usama Arif <usama.arif@arm.com>
Cc: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 217 insertions, 1 deletions

diff --git a/documentation/ref-manual/ref-classes.xml b/documentation/ref-manual/ref-classes.xml
index ab12373ae0..1dcd5fdd03 100644
--- a/documentation/ref-manual/ref-classes.xml
+++ b/documentation/ref-manual/ref-classes.xml
@@ -1880,8 +1880,82 @@ This check was removed for YP 2.3 release
 
     <para>
         The <filename>kernel-fitimage</filename> class provides support to
-        pack zImages.
+        pack a kernel Image, device trees and a RAM disk into a single
+        FIT image. In theory, a FIT image can support any number of kernels,
+        RAM disks and device-trees.
+        However, <filename>kernel-fitimage</filename> currently only supports
+        limited usescases: just one kernel image, an optional RAM disk, and
+        any number of device tree.
     </para>
+
+    <para>
+        To create a FIT image, it is required that
+        <filename><link linkend='var-KERNEL_CLASSES'>KERNEL_CLASSES</link></filename>
+        is set to "kernel-fitimage" and
+        <filename><link linkend='var-KERNEL_IMAGETYPE'>KERNEL_IMAGETYPE</link></filename>
+        is set to "fitImage".
+    </para>
+
+    <para>
+        The options for the device tree compiler passed to mkimage -D feature
+        when creating the FIT image are specified using the
+        <filename><link linkend='var-UBOOT_MKIMAGE_DTCOPTS'>UBOOT_MKIMAGE_DTCOPTS</link></filename>
+        variable.
+    </para>
+
+    <para>
+        Only a single kernel can be added to the FIT image created by
+        <filename>kernel-fitimage</filename> and the kernel image in FIT is
+        mandatory.
+        The address where the kernel image is to be loaded by U-boot is
+        specified by
+        <filename><link linkend='var-UBOOT_LOADADDRESS'>UBOOT_LOADADDRESS</link></filename>
+        and the entrypoint by
+        <filename><link linkend='var-UBOOT_ENTRYPOINT'>UBOOT_ENTRYPOINT</link></filename>.
+    </para>
+
+    <para>
+        Multiple device trees can be added to the FIT image created by
+        <filename>kernel-fitimage</filename> and the device tree is optional.
+        The address where the device tree is to be loaded by U-boot is
+        specified by
+        <filename><link linkend='var-UBOOT_DTBO_LOADADDRESS'>UBOOT_DTBO_LOADADDRESS</link></filename>
+        for device tree overlays and by
+        <filename><link linkend='var-UBOOT_DTB_LOADADDRESS'>UBOOT_DTB_LOADADDRESS</link></filename>
+        for device tree binaries.
+    </para>
+
+    <para>
+        Only a single RAM disk can be added to the FIT image created by
+        <filename>kernel-fitimage</filename> and the RAM disk in FIT is
+        optional.
+        The address where the RAM disk image is to be loaded by U-boot
+        is specified by
+        <filename><link linkend='var-UBOOT_RD_LOADADDRESS'>UBOOT_RD_LOADADDRESS</link></filename>
+        and the entrypoint by
+        <filename><link linkend='var-UBOOT_RD_ENTRYPOINT'>UBOOT_RD_ENTRYPOINT</link></filename>.
+        The ramdisk is added to FIT image when
+        <filename><link linkend='var-INITRAMFS_IMAGE'>INITRAMFS_IMAGE</link></filename>
+        is specified.
+    </para>
+
+    <para>
+        The FIT image generated by <filename>kernel-fitimage</filename> class
+        is signed when the variables
+        <filename><link linkend='var-UBOOT_SIGN_ENABLE'>UBOOT_SIGN_ENABLE</link></filename>,
+        <filename><link linkend='var-UBOOT_MKIMAGE_DTCOPTS'>UBOOT_MKIMAGE_DTCOPTS</link></filename>,
+        <filename><link linkend='var-UBOOT_SIGN_KEYDIR'>UBOOT_SIGN_KEYDIR</link></filename>
+        and
+        <filename><link linkend='var-UBOOT_SIGN_KEYNAME'>UBOOT_SIGN_KEYNAME</link></filename>
+        are set appropriately.
+        The default values used for
+        <filename><link linkend='var-FIT_HASH_ALG'>FIT_HASH_ALG</link></filename>
+        and
+        <filename><link linkend='var-FIT_SIGN_ALG'>FIT_SIGN_ALG</link></filename>
+        in <filename>kernel-fitimage</filename> are "sha256" and "rsa2048"
+        respectively.
+    </para>
+
 </section>
 
 <section id='ref-classes-kernel-grub'>
diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 8cc7ef8fc9..a5064807e5 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -4991,6 +4991,30 @@
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-FIT_HASH_ALG'><glossterm>FIT_HASH_ALG</glossterm>
+            <info>
+               FIT_HASH_ALG[doc] = "Specifies the hash algorithm used in creating the FIT Image."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+                    Specifies the hash algorithm used in creating the FIT Image.
+                    For e.g. sha256.
+                </para>
+            </glossdef>
+        </glossentry>
+
+        <glossentry id='var-FIT_SIGN_ALG'><glossterm>FIT_SIGN_ALG</glossterm>
+            <info>
+               FIT_SIGN_ALG[doc] = "Specifies the signature algorithm used in creating the FIT Image."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+                    Specifies the signature algorithm used in creating the FIT Image.
+                    For e.g. rsa2048.
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-FONT_EXTRA_RDEPENDS'><glossterm>FONT_EXTRA_RDEPENDS</glossterm>
             <info>
                 FONT_EXTRA_RDEPENDS[doc] = "When a recipe inherits the fontcache class, this variable specifies runtime dependencies for font packages. This variable defaults to 'fontconfig-utils'."
@@ -15960,6 +15984,38 @@
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-UBOOT_DTB_LOADADDRESS'><glossterm>UBOOT_DTB_LOADADDRESS</glossterm>
+            <info>
+               UBOOT_DTB_LOADADDRESS[doc] = "Specifies the load address for the dtb."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+                    Specifies the load address for the dtb image used by U-boot.
+                    During FIT image creation, the
+                    <filename>UBOOT_DTB_LOADADDRESS</filename> variable is used
+                    in <filename>kernel-fitimage</filename> class to specify the
+                    load address to be used in creating the dtb sections of
+                    Image Tree Source for the FIT image.
+                </para>
+            </glossdef>
+        </glossentry>
+
+        <glossentry id='var-UBOOT_DTBO_LOADADDRESS'><glossterm>UBOOT_DTBO_LOADADDRESS</glossterm>
+            <info>
+               UBOOT_DTBO_LOADADDRESS[doc] = "Specifies the load address for the dtbo."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+                    Specifies the load address for the dtbo image used by U-boot.
+                    During FIT image creation, the
+                    <filename>UBOOT_DTBO_LOADADDRESS</filename> variable is used
+                    in <filename>kernel-fitimage</filename> class to specify the
+                    load address to be used in creating the dtbo sections of
+                    Image Tree Source for the FIT image.
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-UBOOT_ENTRYPOINT'><glossterm>UBOOT_ENTRYPOINT</glossterm>
             <info>
                UBOOT_ENTRYPOINT[doc] = "Specifies the entry point for the U-Boot image."
@@ -16045,6 +16101,51 @@
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-UBOOT_MKIMAGE_DTCOPTS'><glossterm>UBOOT_MKIMAGE_DTCOPTS</glossterm>
+            <info>
+               UBOOT_MKIMAGE_DTCOPTS[doc] = "Options for the device tree compiler passed to mkimage '-D' feature."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+                    Options for the device tree compiler passed to mkimage '-D'
+                    feature while creating FIT image in
+                    <filename>kernel-fitimage</filename> class.
+                </para>
+            </glossdef>
+        </glossentry>
+
+        <glossentry id='var-UBOOT_RD_LOADADDRESS'><glossterm>UBOOT_RD_LOADADDRESS</glossterm>
+            <info>
+               UBOOT_RD_LOADADDRESS[doc] = "Specifies the load address for the ramdisk image."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+                    Specifies the load address for the RAM disk image.
+                    During FIT image creation, the
+                    <filename>UBOOT_RD_LOADADDRESS</filename> variable is used
+                    in <filename>kernel-fitimage</filename> class to specify the
+                    load address to be used in creating the Image Tree Source for
+                    the FIT image.
+                </para>
+            </glossdef>
+        </glossentry>
+
+        <glossentry id='var-UBOOT_RD_ENTRYPOINT'><glossterm>UBOOT_RD_ENTRYPOINT</glossterm>
+            <info>
+               UBOOT_RD_ENTRYPOINT[doc] = "Specifies the entrypoint for the ramdisk image."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+                    Specifies the entrypoint for the RAM disk image.
+                    During FIT image creation, the
+                    <filename>UBOOT_RD_ENTRYPOINT</filename> variable is used
+                    in <filename>kernel-fitimage</filename> class to specify the
+                    entrypoint to be used in creating the Image Tree Source for
+                    the FIT image.
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-UBOOT_SUFFIX'><glossterm>UBOOT_SUFFIX</glossterm>
             <info>
                UBOOT_SUFFIX[doc] = "Points to the generated U-Boot extension."
@@ -16063,6 +16164,47 @@
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-UBOOT_SIGN_ENABLE'><glossterm>UBOOT_SIGN_ENABLE</glossterm>
+            <info>
+               UBOOT_SIGN_KEYDIR[doc] = "Enable signing of FIT image."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+                    Enable signing of FIT image. The default value is "0".
+                </para>
+            </glossdef>
+        </glossentry>
+
+        <glossentry id='var-UBOOT_SIGN_KEYDIR'><glossterm>UBOOT_SIGN_KEYDIR</glossterm>
+            <info>
+               UBOOT_SIGN_KEYDIR[doc] = "Location of the directory containing the RSA key and certificate used for signing FIT image."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+                    Location of the directory containing the RSA key and
+                    certificate used for signing FIT image.
+                </para>
+            </glossdef>
+        </glossentry>
+
+        <glossentry id='var-UBOOT_SIGN_KEYNAME'><glossterm>UBOOT_SIGN_KEYNAME</glossterm>
+            <info>
+               UBOOT_SIGN_KEYNAME[doc] = "The name of keys used for signing U-boot FIT image"
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+                    The name of keys used for signing U-boot FIT image stored in
+                    <filename><link linkend='var-UBOOT_SIGN_KEYDIR'>UBOOT_SIGN_KEYDIR</link></filename>
+                    directory. For e.g. dev.key key and dev.crt certificate
+                    stored in
+                    <filename><link linkend='var-UBOOT_SIGN_KEYDIR'>UBOOT_SIGN_KEYDIR</link></filename>
+                    directory will have
+                    <filename><link linkend='var-UBOOT_SIGN_KEYNAME'>UBOOT_SIGN_KEYNAME</link></filename>
+                    set to "dev".
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-UBOOT_TARGET'><glossterm>UBOOT_TARGET</glossterm>
             <info>
                UBOOT_TARGET[doc] = "Specifies the target used for building U-Boot."