A question about "gptprio.next"

[Jovi Zhangwei]

Hi,


When I look into CoreOS's grub config, I cannot understand the meaning of 
"gptprio.next", also cannot find any clue in Grub Manual.

So does anyone knows the meaning of gptprio.next instruction? great thanks. 


menuentry "CoreOS default" --id=coreos {

    gptprio.next -d usr -u usr_uuid

    if [ "$usr_uuid" = "7130c94a-213a-4e5a-8e26-6cce9662f132" ]; then

      linux$suf /coreos/vmlinuz-a @@MOUNTUSR@@=PARTUUID=$usr_uuid 
$linux_cmdline

    else

      linux$suf /coreos/vmlinuz-b @@MOUNTUSR@@=PARTUUID=$usr_uuid 
$linux_cmdline

    fi

}