[syslinux] Is efiboot.img required?

Thomas Schmitt scdbackup at gmx.net
Sun Apr 5 07:18:30 PDT 2015


Hi,

i wrote:
> >   http://mjg59.dreamwidth.org/11285.html

piranna at gmail.com wrote:
> There it says about creating a third El Torito image only for Macs,
> since old ones could fail and this could be the problem I'm having.

The third boot image is HFS+, not FAT.
I understand this is for pre-EFI Macs.

Try a Debian amd64 ISO, e.g.:
  http://cdimage.debian.org/debian-cd/7.8.0/amd64/iso-cd/debian-7.8.0-amd64-netinst.iso
It does not have a HFS+ boot image, other than
Fedora-LiveCD.iso.


> > Of course, piranna could set up an EFI capable disk boot
> > image by help of SYSLINUX. But that would not boot from
> > optical media.

> This is what I've done, a FAT disk image with syslinux.efi and embed
> it inside the IsoHybrid disk image, but when dd'd to the USB pendrive,

I meant a disk-only image. No ISO, no hybrid.
Just an ESP and an operating system partition.
Created by partition editor, filesystem formatter,
and populated with files by you and SYSLINUX.


> SysLinux.efi loads the Linux kernel and its initramfs file but doesn't
> boot... :-/ As I put in the initial message I'm not using the
> /efi/boot/bootx64.efi path but instead just copied all files in the
> root directory of the FAT disk image, but since it already load the
> kernel and the initramfs maybe the canonical path is not required...
> is it? Do I need to use the canonical one (and why)?

I would have expected that EFI falls back to the EFI shell
if no /efi/boot/bootx64.efi is present in the ESP.

Hrmpf ... The file names are defined in 3.4.1.1 "Removable Media
Boot Behavior". In general, the file paths can be set by a NVRAM
variable (FilePathList[0] ?) for particular devices.

Do you have indications that syslinux.efi was really executed ?


> > The only non-expert option is --uefi.
> > There is no further non-expert documentation known to me.

> I think --mac could fall in this topic too.

Cough. I still riddle how to describe UEFI.
HFS+ for old Macs would introduce the topic of file blessing.
Not to speak of the fact that no tangible info is available
about the range of Macs which need it.


> Info about creation of the FAT disk image, and if there's any
> diference (that seems there are), example for EFI-based Macs.

First we would have to produce a SYSLINUX based ESP image
which is able to boot Linux so that it can use the surrounding
ISO 9660 filesystem.


Have a nice day :)

Thomas



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