boot.iso vs netinst.iso vs efiboot.img

[Chris Murphy]

Documentation says to use boot.iso to create minimal boot media for BIOS, and efiboot.img for UEFI. This appears to be outdated but I need some clarification on a few things before taking it up with the docs team. Here is the docs page for reference, I'm referring to the preface and the matrix:

http://docs.fedoraproject.org/en-US/Fedora/18/html/Installation_Guide/sn-making-media.html

These two files are identical:

/pub/fedora/linux/releases/18/Fedora/x86_64/os/images/boot.iso
/pub/fedora/linux/releases/18/Fedora/x86_64/iso/Fedora-18-x86_64-netinst.iso

They have the same sha256sum. So what's the distinction? Why different locations and names? I'm going to guess that boot.iso forms the base bootable installer for everything else; and netins is the "public" version of this. Yet documentation tells users to download boot.iso. It seems to be a more obscure file, slightly more difficult to locate, and impossible to know what version of Fedora it is unless you look inside or boot it. Conclusion: we should tell users to use netinst if they want to create minimal boot media. Agree? Disagree (and why)?

Next, what is the use case for efiboot.img? Because I can't figure out why I'd use it, at all. It only contains boot loaders. There's no vmlinuz, initrd, system, or installer. So it does not qualify as minimal boot media, yet that's what's recommended in documentation for UEFI minimal boot media. In fact, the last three UEFI entries in the matrix appear to be wrong:

1. UEFI/Installation USB flash drive: This works with the DVD ISO dd'd to USB media. It even appears to work for UEFI Secure Boot, when dd'd. I can't vouch for any other method [1].

2. Boot CD or boot DVD: This works with the netinst.iso burned to actual media.

3. Boot USB flash drive: efiboot.img does not work as "minimal bootable USB flash drive that boots the installer". However, netinst.iso dd'd to a USB stick does work.

So it appears in every single case where boot.iso is in the matrix, where efiboot.img is in the matrix, and two "Not available" notes in the matrix, all work with netinst.iso (or the one case of DVD ISO dd'd to USB media). Am I understanding this correctly?

Chris Murphy

[1] I'm honestly confused why LiveCD Creator is recommended first and second. Livecd-tools is recommended 3rd. And dd is linguistically not recommended, ergo recommended only as a last resort. I have had extremely high success with dd to USB media, and comparatively low success with the other methods. livecd-tools can be as good, but it's 15000% more complicated, and the Installation Guide provides zero guidance on any of the livecd-tools switches for either UEFI use case, so failure here will be very high.

Why is this order being used? dd is recommended dead last, really? Maybe someone more experienced with installations with the various methods can convince me that dd is actually pretty flakey and I've been lucky.