Error mounting iso image when installing CentOS 7 from USB flash via UEFI, where am I wrong?

Question

ISO

I'm making a multiboot flash drive with iso images. The flash drive has two sections:

1. FAT32, 512 MB, with EFI folder, there is grub.cfg
   
2. FAT32, 31GB, with an iso folder, there are images in folders
   

grub.cfg content:

set timeout=10
set color_highlight=black/light-magenta

set root=(hd0,msdos2)

menuentry 'Install CentOS 7 Minimal from ISO' {
        set isofile="/iso/centos7minimal/CentOS-7-x86_64-Minimal-1511.iso"
        loopback loop $isofile
        linux (loop)/isolinux/vmlinuz iso-scan/filename=$isofile noeject
        initrd (loop)/isolinux/initrd.img
}

menuentry 'Install Ubuntu Server 16.04 from ISO' {
        set isofile="/iso/ubuntuserver16.04/ubuntu-16.04-server-amd64.iso"
        loopback loop $isofile
        linux (loop)/install/vmlinuz
        initrd (loop)/install/initrd.gz
}

The Ubuntu installer loads without problems and you can start the actual installation. I didn't get past the beginning.
What happened with CentOS:

• the installer loads up to the point kernel: loop: module loadedand starts thinking
  
• after about 2 minutes a repeated message appears

  dracut-initqueue timeout - starting timeout scripts

  
  
• this ends
  

Did you make a mistake in the config or is it a bug / feature of the installer?

Answer 1

Most likely, when loading, there is no section where the iso lies, you need to add where to look for it. Something like

linux (loop)/isolinux/vmlinuz iso-scan/filename=$isofile noeject root=live:LABEL=метка_раздела_флэшки rd.live.image