set kernel_url http://${boot_domain}/ubuntu-squash/20.04.1-8de3099a/
set codename focal
set version_number 20.04.1
goto sub_boot
:groovy
set kernel_url http://${boot_domain}/ubuntu-squash/20.10-424a54b4/
set codename groovy
set version_number 20.10
goto sub_boot
:sub_boot
imgfree
isset ${dhcp-server} && set netboot_params ip=dhcp url=https://mirrors.aliyun.com/ubuntu-releases/${codename}/ubuntu-${version_number}-live-server-${arch_a}.iso || set netboot_params