1NXP i.MX 8M Series
2==================
3
4The i.MX 8M family of applications processors based on Arm Corte-A53 and Cortex-M4
5cores provide high-performance computing, power efficiency, enhanced system
6reliability and embedded security needed to drive the growth of fast-growing
7edge node computing, streaming multimedia, and machine learning applications.
8
9imx8mq is dropped in TF-A CI build due to the small OCRAM size, but still actively
10maintained in NXP official release.
11
12Boot Sequence
13-------------
14
15Bootrom --> SPL --> BL31 --> BL33(u-boot) --> Linux kernel
16
17How to build
18------------
19
20Build Procedure
21~~~~~~~~~~~~~~~
22
23-  Prepare AARCH64 toolchain.
24
25-  Build spl and u-boot firstly, and get binary images: u-boot-spl.bin,
26   u-boot-nodtb.bin and dtb for the target board.
27
28-  Build TF-A
29
30   Build bl31:
31
32   .. code:: shell
33
34       CROSS_COMPILE=aarch64-linux-gnu- make PLAT=<Target_SoC> bl31
35
36   Target_SoC should be "imx8mq" for i.MX8MQ SoC.
37   Target_SoC should be "imx8mm" for i.MX8MM SoC.
38   Target_SoC should be "imx8mn" for i.MX8MN SoC.
39   Target_SoC should be "imx8mp" for i.MX8MP SoC.
40
41Deploy TF-A Images
42~~~~~~~~~~~~~~~~~~
43
44TF-A binary(bl31.bin), u-boot-spl.bin u-boot-nodtb.bin and dtb are combined
45together to generate a binary file called flash.bin, the imx-mkimage tool is
46used to generate flash.bin, and flash.bin needs to be flashed into SD card
47with certain offset for BOOT ROM. the u-boot and imx-mkimage will be upstreamed
48soon, this doc will be updated once they are ready, and the link will be posted.
49
50TBBR Boot Sequence
51------------------
52
53When setting NEED_BL2=1 on imx8mm. We support an alternative way of
54boot sequence to support TBBR.
55
56Bootrom --> SPL --> BL2 --> BL31 --> BL33(u-boot with UEFI) --> grub
57
58This helps us to fulfill the SystemReady EBBR standard.
59BL2 will be in the FIT image and SPL will verify it.
60All of the BL3x will be put in the FIP image. BL2 will verify them.
61In U-boot we turn on the UEFI secure boot features so it can verify
62grub. And we use grub to verify linux kernel.
63