开发板资料请参考如下网址： https://doc.embedfire.com/products/link/zh/latest/linux/ebf_i.mx6ull.html
nxp 提供了丰富的软件sdk, 如果能利用NXP的提供的最新的sdk资源，搭配低成本的硬件方案，强强联合使产品更有竞争力，更方便爱好者学习使用，我们采用最新的SDK版本L6.1.36-2.1.0来做适配。
1.首先利用DDR压力测试工具生成ddr参数，可以参考之前的文档https://www.lijiandong.com.cn/?p=110
IMX6ULL DDR压力测试工具网址：
压力测试生成的log文件如下，更新如下Calibration寄存器到uboot的代码里
MMDC registers updated from calibration
Write leveling calibration
MMDC_MPWLDECTRL0 ch0 (0x021b080c) = 0x00050003
MMDC_MPWLDECTRL1 ch0 (0x021b0810) = 0x00060006
Read DQS Gating calibration
MPDGCTRL0 PHY0 (0x021b083c) = 0x413C0140
MPDGCTRL1 PHY0 (0x021b0840) = 0x00000000
Read calibration
MPRDDLCTL PHY0 (0x021b0848) = 0x40402E34
Write calibration
MPWRDLCTL PHY0 (0x021b0850) = 0x40403430
Success: DDR calibration completed!!!
更新uboot-imx/board/freescale/mx6ullevk/imximage.cfg文件，根据log修改对应ddr寄存器的值如下：
DATA 4 0x021B080C 0x00050003
DATA 4 0x021B0810 0x00060006
DATA 4 0x021B083C 0x413C0140
DATA 4 0x021B0840 0x00000000
DATA 4 0x021B0848 0x40402E34
DATA 4 0x021B0850 0x40403430
如果更换的DDR3颗粒容量大小有变化，请修改如下两个寄存器，比如采用2Gb容量颗粒后
DATA 4 0x021B0040 0x00000047
DATA 4 0x021B0000 0x83180000
修改 source/meta-bsp/conf/machine/imx6ull14x14evk.conf,
配置编译nand版本image 默认编译的是sd image: UBOOT_CONFIG ??= “nand”
开发板自带4Gb Nand, 因为nand 都兼容ONFI标准，所以软件部分基本不用做修改,执行如下命令重新编译生成nand 版本uboot image
bitbake -c compile -f uboot-imx
bitbake uboot-imx
为了方便uuu烧写image工具修改如下文件：
source/meta-imx/meta-bsp/conf/machine/include/imx-base-extend.inc
修改默认生成的rootfs文件压缩格式为tar.bz2,增加tar.bz2
SOC_DEFAULT_IMAGE_FSTYPES = “wic.bmap wic.zst tar.zst tar.bz2“
bitbake imx-image-core #生成新的tar.bz2压缩格式的文件系统, 参考sdk文档根据具体应用需求可以生成不同的文件系统，比如fsl-image-qt5.
uuu 烧写工具是新一代的量产烧写工具，相比于之前的mfgtools功能上有很多增强。工具网址：https://github.com/nxp-imx/mfgtools/wiki
uuu工具通过uboot的fastboot模式，通过usb口进行烧写image, 针对nand烧写，只通过uboot fastboot模式是不行的，需要加载linux ramfs文件系统才可以，参考如下说明：
What Firmware Need
| What you want | Firmware Need |
|---|---|
| Download bootloader | N/A |
| Burn Image to eMMC/SD | uboot with fastboot enable |
| Burn Image to qspi\spi\nor | uboot with fastboot enable |
| Burn Image into Nand flash | uboot(1), linux kernel\initramfs\uboot\dtb |
| Need linux shell cmd such as fdisk | uboot(1), linux kernel\initramfs\uboot\dtb |
| Boot linux kenrel with rootfs already in eMMC | uboot with fastboot enable |
| Boot Linux kernel with nfs over USB | uboot with fastboot enable, initramfs |
执行如下命令生成uuu下载需要的文件： bitbake fsl-image-mfgtool-initramfs
参考uuu.pdf文件，uuu nand flash 烧写需要的脚本如下：
# Please replace below item with actual name
# @_flash_fw.bin | boot loader firmware, for i.MX8QM/QX, it's different from _flash.bin, for all other platforms, it's same as _flash.bin
# @_flash.bin | boot loader file burn to NAND
# @_Image | linux kernel image, zImage for arm32, Image for arm64
# @_board.dtb | board dtb file
# @_initramfs.cpio.gz.uboot | initramfs
# @_tee | optee image
# @_rootfs.tar.bz2 | rootfs
# This command will be run when i.MX6/7 i.MX8MM, i.MX8MQ
SDP: boot -f u-boot-nand.imx
# This command will be run when ROM support stream mode
# i.MX8QXP, i.MX8QM
SDPS: boot -f u-boot-nand.imx
# These commands will be run when use SPL and will be skipped if no spl
# SDPU will be deprecated. please use SDPV instead of SDPU
# {
SDPU: delay 1000
SDPU: write -f u-boot-nand.imx -offset 0x57c00
SDPU: jump
# }
# These commands will be run when use SPL and will be skipped if no spl
# if (SPL support SDPV)
# {
SDPV: delay 1000
SDPV: write -f u-boot-nand.imx -skipspl
SDPV: jump
# }
FB: ucmd setenv fastboot_buffer ${loadaddr}
FB: download -f zImage
FB: ucmd setenv fastboot_buffer ${fdt_addr}
FB: download -f imx6ul-14x14-evk-gpmi-weim.dtb
FB: ucmd setenv fastboot_buffer ${initrd_addr}
FB: download -f fsl-image-mfgtool-initramfs-imx6ulevk.cpio.zst.u-boot
FB: ucmd setenv bootargs ${bootargs} ${mtdparts}
#FB: ucmd setenv bootargs console=ttymxc3,115200 ${mtdparts}
FB: acmd ${kboot} ${loadaddr} ${initrd_addr} ${fdt_addr}
FBK: ucmd cat /proc/mtd
FBK: ucmd cat /proc/mtd | while read dev size erase name; do mtd=${dev:3}; mtd=${mtd%:}; name=${name%\"}; name=${name#\"}; echo export $name=$mtd >> /tmp/mtd.sh; done;
FBK: ucmd chmod 777 /tmp/mtd.sh
FBK: ucmd mount -t debugfs debugfs /sys/kernel/debug
# write boot loader
FBK: ucmd source /tmp/mtd.sh; flash_erase /dev/mtd${nandboot} 0 0
FBK: ucp u-boot-nand.imx t:/tmp/boot
FBK: ucmd source /tmp/mtd.sh; cd /tmp; if ! [[ `cat /sys/devices/soc0/soc_id` = *"MX8Q"* ]]; then pad="-x"; fi; kobs-ng init $pad -v --chip_0_device_path=/dev/mtd${nandboot} /tmp/boot
# burn FIT
FBK: ucmd if [[ `cat /tmp/mtd.sh` = *"nandfit"* ]]; then source /tmp/mtd.sh;flash_erase /dev/mtd${nandfit} 0 0; dd if=/tmp/boot of=/tmp/fit; nandwrite -p /dev/mtd${nandfit} -p /tmp/fit; fi
# burn kernel
FBK: ucmd source /tmp/mtd.sh; flash_erase /dev/mtd${nandkernel} 0 0
FBK: ucp zImage t:/tmp/img
FBK: ucmd source /tmp/mtd.sh; nandwrite -p /dev/mtd${nandkernel} -p /tmp/img
# burn dtb
FBK: ucmd source /tmp/mtd.sh; flash_erase /dev/mtd${nanddtb} 0 0
FBK: ucp imx6ul-14x14-evk-gpmi-weim.dtb t:/tmp/dtb
FBK: ucmd source /tmp/mtd.sh; nandwrite -p /dev/mtd${nanddtb} -p /tmp/dtb
# burn uTee
FBK: ucmd source /tmp/mtd.sh; flash_erase /dev/mtd${nandtee} 0 0
FBK: ucp tee t:/tmp/tee
FBK: ucmd source /tmp/mtd.sh; nandwrite -p /dev/mtd${nandtee} -p /tmp/tee
# burn rootfs
FBK: ucmd source /tmp/mtd.sh; flash_erase /dev/mtd${nandrootfs} 0 0
FBK: ucmd source /tmp/mtd.sh; ubiattach /dev/ubi_ctrl -m ${nandrootfs}
FBK: ucmd source /tmp/mtd.sh; ubimkvol /dev/ubi0 -Nnandrootfs -m
FBK: ucmd source /tmp/mtd.sh; mkdir -p /mnt/mtd
FBK: ucmd source /tmp/mtd.sh; mount -t ubifs ubi0:nandrootfs /mnt/mtd
FBK: acmd export EXTRACT_UNSAFE_SYMLINKS=1; tar -jx -C /mnt/mtd
FBK: ucp rootfs.tar.bz2 t:-
FBK: sync
FBK: ucmd umount /mnt/mtd
FBK: done注意脚本里要下载和烧写的image名称要与实际的image名称对应上。
如果更换不同容量的nand，比如修改为2G nand,需要修改nand分区，并修改image加载地址，参考如下uboot代码，
diff --git a/include/configs/mx6ul_14x14_evk.h b/include/configs/mx6ul_14x14_evk.h
index a89cea359d..b6deb8899d 100644
--- a/include/configs/mx6ul_14x14_evk.h
+++ b/include/configs/mx6ul_14x14_evk.h
@@ -39,7 +39,8 @@
#endif
#ifdef CONFIG_NAND_BOOT
-#define MFG_NAND_PARTITION "mtdparts=gpmi-nand:64m(nandboot),16m(nandkernel),16m(nanddtb),16m(nandtee),-(nandrootfs)"
+#define MFG_NAND_PARTITION "mtdparts=gpmi-nand:8m(nandboot),16m(nandkernel),1m(nanddtb),1m(nandtee),-(nandrootfs)"
+/*#define MFG_NAND_PARTITION "mtdparts=gpmi-nand:64m(nandboot),16m(nandkernel),16m(nanddtb),16m(nandtee),-(nandrootfs)"*/
#else
#define MFG_NAND_PARTITION ""
#endif
@@ -64,14 +65,14 @@
"tee_addr=0x84000000\0" \
"console=ttymxc0\0" \
"bootargs=console=ttymxc0,115200 ubi.mtd=nandrootfs " \
- "root=ubi0:rootfs rootfstype=ubifs " \
+ "root=ubi0:nandrootfs rootfstype=ubifs " \
BOOTARGS_CMA_SIZE \
MFG_NAND_PARTITION \
"\0" \
- "bootcmd=nand read ${loadaddr} 0x4000000 0xc00000;"\
- "nand read ${fdt_addr} 0x5000000 0x100000;"\
+ "bootcmd=nand read ${loadaddr} 0x800000 0xc00000;"\
+ "nand read ${fdt_addr} 0x1800000 0x100000;"\
"if test ${tee} = yes; then " \
- "nand read ${tee_addr} 0x6000000 0x400000;"\
+ "nand read ${tee_addr} 0x1900000 0x400000;"\
"bootm ${tee_addr} - ${fdt_addr};" \
"else " \
"bootz ${loadaddr} - ${fdt_addr};" \
执行 uuu -b 脚本名称 烧写nand image，烧写后系统可以正常启动。后续根据需要修改硬件外设设备树，使开发板外设可用。此mini板采用与nxp官方开发板相同的双百兆网口PHY硬件设计，所以网口可以直接使用。