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Diffstat (limited to 'poky/documentation/ref-manual/ref-classes.xml')
| -rw-r--r-- | poky/documentation/ref-manual/ref-classes.xml | 76 |
1 files changed, 75 insertions, 1 deletions
diff --git a/poky/documentation/ref-manual/ref-classes.xml b/poky/documentation/ref-manual/ref-classes.xml index ab12373ae..1dcd5fdd0 100644 --- a/poky/documentation/ref-manual/ref-classes.xml +++ b/poky/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'> |