Using pxe boot for usb installer

Question

I have a disk image (A) with a custom installation of CentOS 7. This disk image is included in another disk image (B) which also contains an installation of CentOS (minimal) as well as an installer which is using dd to write disk image A to the target disk. Disk image B (which includes disk image A) is then typically written to a usb drive and installation of disk image A is done by booting from this usb drive and running the installer.

Now I would like to have the option to install disk image A using pxe boot as well. Preferably I would like to use disk image B for this, so that I don't have to create two different artifacts, but if this is not possible I am open to alternatives.

I have tried loading disk image B (3.3 Gb) using memdisk, and it starts loading the image, but after a while I get the error message "Not enough memory to load specified image". I have tried resolving this by setting "uppermem" and "append hardisk", but neither does help.

This is by pxe-boot configuration for that label:

label 1 menu label ^5) Custom CentOS uppermem 5000000 kernel memdisk initrd installer_image 

Answer 1

Forget about memedisk.

The first image has to be PXE booted. By editing its init script somehow net retrieve the second image (wget, curl, SMB mapped disk, NFS, etc) next the init script has to do what it always did installing the second image with dd etc etc.. On a PXE environment every component must be net-retrieved before its use.