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This article describes a flow to build a CentOS 8 system for Zynq UltraScale+ which includes building UEFI firmware, building the CentOS 8 kernel and installing these images on a prebuilt CentOS 8 disk image for booting on a ZCU102.

Table of Contents

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Because the installed CentOS kernel image may not include some critical configurations required for Zynq UltraScale+, you may need to build a bootstrap kernel. Once we boot the bootstrap kernel, we can formally install the kernel RPMS which will install installs the newly configured kernel , update and updates the initrd , and update the GRUB configuration.

$ grep 'SERIAL_XILINX\|ARCH_ZYNQMP\|SDHCI_OF_ARASAN' SOURCES/kernel-aarch64.config

If all of these are options are enabled, then the installed kernel should support Zynq UltraScale+ and you can skip this sectionThese are the minimal kernel configs required to boot the ZCU102 from an SD card with serial console.

CONFIG_ARCH_ZYNQMP=y
CONFIG_SERIAL_XILINX_PS_UART=y
CONFIG_SERIAL_XILINX_PS_UART_CONSOLE=y
CONFIG_MMC_SDHCI_OF_ARASAN=m

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First we need to run the “%prep” stage in our SPEC file which will unpack and patch the kernel source.

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You may optionally change the password with “virt-customize”.

$ virt-customize -a CentOS-8-aarch64-1905-dvd1.qcow2 --root-password password:zynqmp

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$ qemu-img convert CentOS-8-aarch64-1905-dvd1.qcow2 CentOS-8-aarch64-1905-dvd1.raw

Now lets examine the partitions in this disk image. You will see there are 3 partitions. The first is the EFI System Partition (ESP) which is a FAT formatted partition. The second partition is an EXT4 Linux partition. The third partition is an LVM root filesystem.

$ fdisk -l CentOS-8-aarch64-1905-dvd1.raw
Disk CentOS-8-aarch64-1905-dvd1.raw: 7 GiB, 7516192768 bytes, 14680064 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: E51C2C48-87F2-419D-BA13-687E3930A160

Device                            Start      End  Sectors  Size Type
CentOS-8-aarch64-1905-dvd1.raw1    2048  1230847  1228800  600M EFI System
CentOS-8-aarch64-1905-dvd1.raw2 1230848  3327999  2097152    1G Linux filesystem
CentOS-8-aarch64-1905-dvd1.raw3 3328000 14678015 11350016  5.4G Linux LVM

The first thing we note is that “Disklabel type” is set to “gpt”. However, Zynq UltraScale+ only support MBR partitioned disks, so we need to convert from GPT to MBR with “sgdisk”.

$ sgdisk -m 1:2:3 CentOS-8-aarch64-1905-dvd1.raw
Warning: The kernel is still using the old partition table.
The new table will be used at the next reboot or after you
run partprobe(8) or kpartx(8)
GPT data structures destroyed! You may now partition the disk using fdisk or
other utilities.

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$ sfdisk -A CentOS-8-aarch64-1905-dvd1.raw 1
The bootable flag on partition 1 is enabled now.

The partition table has been altered.
Syncing disks.

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$ fdisk -l CentOS-8-aarch64-1905-dvd1.raw
Disk CentOS-8-aarch64-1905-dvd1.raw: 7 GiB, 7516192768 bytes, 14680064 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device                          Boot   Start      End  Sectors  Size Id Type
CentOS-8-aarch64-1905-dvd1.raw1 *       2048  1230847  1228800  600M ef EFI (FAT-12/16/32)
CentOS-8-aarch64-1905-dvd1.raw2      1230848  3327999  2097152    1G 83 Linux
CentOS-8-aarch64-1905-dvd1.raw3      3328000 14678015 11350016  5.4G 8e Linux LVM

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$ cd $COS_BUILD/images
$ sudo kpartx -va CentOS-8-aarch64-1905-dvd1.raw
add map loop0p1 (253:12): 0 1228800 linear 7:4 2048
add map loop0p2 (253:13): 0 2097152 linear 7:4 1230848
add map loop0p3 (253:14): 0 11350016 linear 7:4 3328000
$ sudo mount /dev/mapper/loop0p1 efi
$ sudo mount /dev/mapper/loop0p2 boot

The Zynq UltraScale+ boot ROM will search for boot“boot.bin bin” on the first partition. The boot ROM will load FSBL and PMU firmware. FSBL will in turn load the u-boot. U-boot acting as the UEFI firmware will search the current partition for the corresponding board DTB file and pass it to the EFI bootloader through the EFI configuration table. If it doesn’t find one, it will pass its own DTB to the EFI bootloader. However, this DTB may not be compatible with your kernel version, so I recommend using the DTB built with the kernel. So let's install the UEFI firmware (boot.bin) and ZCU102 DTB as shown below from the deploy directory.

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Since we are not using UEFI secure boot, we want to boot GRUB directly. So we need to replace shim (bootaa64.efi) with GRUB (grubaa64.efi). Note that we need to maintain the naming convention bootaa64.efi. That is the name searched for by the UEFI firmware.

$ sudo cp efi/EFI/centos/grubaa64.efi efi/EFI/BOOT/bootaa64.efi

Next lets install the bootstrap kernel and kernel RPM packages into the BOOT directory.

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$ sudo umount efi
$ sudo umount boot
$ sudo kpartx -d CentOS-8-aarch64-1905-dvd1.raw
loop deleted : /dev/loop0

Now the raw disk image is ready to write to the SD card. With the CD card plugged into your CentOS machine, note the device node of your card (/dev/sdX) and install the image as shown below.

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$ sudo dd if=CentOS-8-aarch64-1905-dvd1.raw of=/dev/sdX bs=4M iflag=fullblock oflag=direct status=progress; sync

Booting ZCU102

Open a terminal emulator of your choice on your host machine and connect to the serial port on the ZCU102. Insert the SD card on the ZCU102, make sure the dip switches are set to SD boot and power on the board. If everything goes well, you should see an FSBL banner, PMU firmware version and U-boot messages.

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