ImageBuilder

Building an embedded virtualized system with anything more than one Domain can be difficult, error prone and time consuming.

ImageBuilder, an Open Source collection of scripts (contributions encouraged), changes all that.

ImageBuilder generates a U-Boot script that can be used to load all of the binaries automatically and boot the full system fast. Given a collection of binaries such as Xen, Dom0 and a number of Dom0-less DomUs, ImageBuilder takes care of calculating all loading addresses, editing device tree with the necessary information, and even pre-configuring a disk image with kernels and rootfses.

ImageBuilder has been tested on Xilinx ZynqMP MPSoC boards. An up-to-date wikipage is also available at wiki.xenproject.org.

scripts/uboot-script-gen

The ImageBuilder script that generates a u-boot script to load all your binaries for a Xen Dom0-less setup is scripts/uboot-script-gen.

To use it, first write a config file like config:

MEMORY_START="0x0"
MEMORY_END="0x80000000"

DEVICE_TREE="mpsoc.dtb"
XEN="xen"
XEN_CMD="console=dtuart dtuart=serial0 dom0_mem=1G dom0_max_vcpus=1 bootscrub=0 vwfi=native sched=null"
DOM0_KERNEL="Image-dom0"
DOM0_CMD="console=hvc0 earlycon=xen earlyprintk=xen clk_ignore_unused"
DOM0_RAMDISK="dom0-ramdisk.cpio"

NUM_DOMUS=2
DOMU_KERNEL[0]="zynqmp-dom1/Image-domU"
DOMU_RAMDISK[0]="zynqmp-dom1/domU-ramdisk.cpio"
DOMU_PASSTHROUGH_DTB[0]="zynqmp-dom1/passthrough-example-part.dtb"
DOMU_KERNEL[1]="zynqmp-dom2/Image-domU"
DOMU_RAMDISK[1]="zynqmp-dom2/domU-ramdisk.cpio"
DOMU_MEM[1]=512
DOMU_VCPUS[1]=1

UBOOT_SOURCE="boot.source"
UBOOT_SCRIPT="boot.scr"

Where:

• MEMORY_START and MEMORY_END specify the start and end of RAM.

• DEVICE_TREE specifies the DTB file to load.

• XEN specifies the Xen hypervisor binary to load. Note that it has to be a regular Xen binary, not a u-boot binary.

• XEN_CMD specifies the command line arguments used for Xen. If not set, the default one will be used.

• DOM0_KERNEL specifies the Dom0 kernel file to load.

• DOM0_CMD specifies the command line arguments for Dom0's Linux kernel. If "root=" isn't set, imagebuilder will try to determine it. If not set at all, the default one is used.

• DOM0_RAMDISK specifies the Dom0 ramdisk to use. Note that it should be a regular ramdisk cpio.gz file, not a u-boot binary.

• NUM_DOMUS specifies how many Dom0-less DomUs to load

• DOMU_KERNEL[number] specifies the DomU kernel to use.

• DOMU_RAMDISK[number] specifies the DomU ramdisk to use.

• DOMU_PASSTHROUGH_DTB[number] specifies the device assignment configuration, see xen.git:docs/misc/arm/passthrough.txt

• DOMU_MEM[number] is the amount of memory for the VM in MB, default 512MB

• DOMU_VCPUS[number] is the number of vcpus for the VM, default 1

• UBOOT_SOURCE and UBOOT_SCRIPT specify the output. They are optional as you can pass -o FILENAME to uboot-script-gen as a command line parameter

Then you can invoke uboot-script-gen as follows:

$ bash ./scripts/uboot-script-gen -c /path/to/config-file -d . -t tftp -o bootscript

Where:
-c specifies the path to the config file to use
-d specifies the "root" directory (paths in the config file are relative to it), this is not a working directory (any output file locations are specified in the config and any temporary files are in /tmp)
-t specifies the u-boot command to load the binaries. "tftp", "sd" and "scsi" are shorthands for "tftpb", "load mmc 0:1" and "load scsi 0:1", but actually any arbitrary command can be used, for instance -t "fatload" is valid.
-o specifies the output filename for the uboot script and its source.\

scripts/disk_image

The ImageBuilder script that generates a disk image file to load on a SD or SATA drive. This creates multiple partitions: 1 boot partition where the boot files from working directory (-c option) are, and 1 additional partition for each Dom0/DomU cpio archive to write to disk.

disk_image will write to disk as separate partition each file specified as follows:

• DOM0_ROOTFS specifies the Dom0 rootfs to use. Note that the file to write should be a regular cpio.gz file, not a u-boot binary.

• DOMU_ROOTFS[number] specifies the DomU rootfs to use. Note that it should be a regular cpio.gz file, not a u-boot binary.

After you've generated the u-boot scripts using the uboot-script-gen script, disk_image is run as follows:

$ sudo bash ./scripts/disk_image -c /path/to/config-file -d . \
                                 -w /path/to/tmp/dir          \
                                 -o /path/to/output/disk.img

Where:
-c specifies the path to the config file to use
-d specifies the working directory (paths in the config file are relative to it)
-w specifies the temporary working directory that the script uses for building the disk image, and if not set, one is created in /tmp
-o specifies the output disk image file name\