install linux on microzed board

The microzed development board has Xilinx zynq7000 chip. It has an application process unit with cortex a9 and FPGA fabric. The board also contains interfaces like SDIO and QSPI. I want to install Linux on it directly with yocto and without petalinux, which runs yocto behind the scene, so I tried to eliminate the need to use it. Why do so?

• It is interesting, and I have a lot of experience with yocto and it very easy to work with its script once you know it
• easy porting to other processors: IMX, stm32Mp157, etc'
• using build tools like CMake,Autotools, and yocto scripts make it very easy to port SW between different processors.

I found that meta-xilinx layer and used it to build a Linux system for the microzed board. Refer here for a list supported bords and creating a custom board can be very easy if one tracks the existing ones.

yocto installation

The basic yocto installation includes poky and meta-Xilinx layers; check out the following yocto layers and switch to zeus branch:

mkdir yocto
cd yocto
git clone git://git.yoctoproject.org/poky.git
git clone https://github.com/Xilinx/meta-xilinx
git clone http://github.com/Xilinx/meta-xilinx-tools
. ./poky/oe-init-build-env

add the meta-xilinx layers:

bitbake-layers add-layer /path/to/meta-xilinx
bitbake-layers add-layer /path/to/meta-xilinx-tools

and change the configration file conf/local.conf:

# to build microzed board
MACHINE ??= "microzed-zynq7"
# to allow c++ 
IMAGE_INSTALL_append = " libstdc++"
TOOLCHAIN_TARGET_TASK_append = " libstdc++-staticdev"

Use the following yocto builds:

# to create minimal CPIO image (3M Bytes) + kernel + u-boot
bitbake core-image-minimal
bitbake u-boot

flash image on QSPI

FSBL

The next step is to generate FSBL application for microzed platform board. The board definition files (BDF) should be installed on vivado as refer here. So, just create a new HW project in vivado for microzed and the export the XSA (of HDF) file to vitis (of SDK) and then create a new FSBL application.

boot.bin

To create the boot.bin file, we can use bootgen, which is a tool of Xilinx or to use mkbootimage which is an open-source replacement for Xilinx bootgen tool. I took the values of the parameters load and offset address from the u-boot file zynq-common.h.

#!/bin/bash
UIMAGE_LOAD=0x3000000
DTB_LOAD=0x2a00000
FS_LOAD=0x2000000

KERNEL_ENTRY=0x100000
DTS_ENTRY=0x600000
RAM_FS_ENTRY=0x620000

cat << EOF > boot.bif
img : { 
	[bootloader]/home/yair/workspace2/fsbl_microzed/Release/fsbl_microzed.elf
	/home/yair/xilinx/yocto/build/tmp/work/microzed_zynq7-poky-linux-gnueabi/u-boot/1_2019.07-r0/build/u-boot.elf
	[load=${UIMAGE_LOAD},offset=${KERNEL_ENTRY}]yocto/build/tmp/work/microzed_zynq7-poky-linux-gnueabi/linux-xlnx/4.19-xilinx-v2019.2+gitAUTOINC+b983d5fd71-r0/deploy-linux-xnx/uImage	
	[load=${DTB_LOAD},offset=${DTS_ENTRY}]yocto/build/tmp/work/microzed_zynq7-poky-linux-gnueabi/linux-xlnx/4.19-xilinx-v2019.2+gitAUTOINC+b983d5fd71-r0/deploy-linux-xlnx/zynq-microzed-microzed-zynq7.dtb	
	[load=${FS_LOAD},offset=${RAM_FS_ENTRY}]yocto/build/tmp/deploy/images/microzed-zynq7/core-image-minimal-microzed-zynq7.cpio.gz.u-boot
}
EOF
bootgen  -image boot.bif -o i boot.bin -w 

flash the board

To flash the image on the qspi is has to set the board at jtag mode and run the following command:

program_flash -f /path/to/boot.bin -offset 0 -flash_type qspi_single -fsbl /path/to/fsbl_microzed.elf -blank_check -verify -cable type xilinx_tcf url TCP:127.0.0.1:3121

also so, it can refer here about how to eliminate the need for JTAG mode by adding this line to FSBL at main.c

/*
 * Read bootmode register
 */
BootModeRegister = Xil_In32(BOOT_MODE_REG);
BootModeRegister &= BOOT_MODES_MASK;

//add this line to trick boot mode to JTAG
BootModeRegister = JTAG_MODE; 

manual boot

This u-boot commands will read files from QSPI and will load the Linux kernel it can also automated using u-boot enviroment variables and scripts.

sf probe 0 0 0 
sf read 0x2000000 0x620000 0x500000
sf read 0x3000000 0x100000 0x5e0000
sf read 0x2a00000 0x600000 0x20000
bootm  0x3000000  0x2000000 0x2a00000

boot image on sd card

The stages for flashing images on the sd card are similar to those that have on the QSPI. But I was to use a completely open-source without FSBL. The idea is to take the boot.bin file ( generated using vivado tools) and replace it with the secondary boot loader (SPL). The most important file is ps7_init_gpl.c which one create it using vivado tools, and it also platforms unique and responsible to initialize the most critical peripherals in the board: The DDR controller, clocks and MIO pins. If a new platform is a design, then, is has to generate a new file for the new platform. It has to copy the following files to the sd card, refer here for more details:

The names mentioned in the table above, are arrived from the file boot.cmd which process of yocto build generates that file.

$ yocto/build/tmp/work/microzed_zynq7-poky-linux-gnueabi/u-boot-zynq-scr/1.0-r0 $ cat boot.cmd
fatload mmc 0 0x2000000 zynq-microzed.dtb
fatload mmc 0 0x2080000 uImage
fatload mmc 0 0x4000000 uramdisk.image.gz
bootm 0x2080000 0x4000000 0x2000000

TO do: Install boot image on QSPI with SPL

To eliminate the FSBL when using QSPI.

References

[1] Creating a Bootable Image and Program the Flash