[syslinux] FWD: Re: Is efiboot.img required?

[Geert Stappers]

For the sake of the discussion.

Screenshots not included due size limit.

----- Forwarded message from syslinux-owner op zytor.com -----

Date: Sun, 05 Apr 2015 17:09:50 -0700
from: syslinux-owner op zytor.com
To: syslinux-owner op zytor.com
Subject: Syslinux post from piranna op gmail.com requires approval

    List:    Syslinux op zytor.com
    From:    piranna op gmail.com
    Subject: Re: [syslinux] Is efiboot.img required?
    Reason:  El cuerpo del mensaje es demasiado grande: 8282739 bytes con un l?mite de 512 KB


Date: Mon, 6 Apr 2015 02:09:10 +0200
from: "piranna op gmail.com" <piranna op gmail.com>
To: Thomas Schmitt <scdbackup op gmx.net>
Cc: syslinux op zytor.com
Subject: Re: [syslinux] Is efiboot.img required?

El 06/04/2015 01:37, "piranna op gmail.com" <piranna op gmail.com> escribió:

> Just to be clear on the topic, I decided to do some tests from scratch
> on my MacBook Pro. This are the steps and results:
>
> 1. I've pick my USB pendrive and zeroed it, and after that created a
> new MBR partition scheme with fdisk and a VFAT partition of 32MB.
> Later I dd'd the file /usr/lib/syslinux/mbr/mbr.bin from SysLinux 6.03
> and set the boot flag on the partition, so it could be able to boot
> SysLinux.
>
> 2. Copied all the files of my IsoHybrid image:
>
> - initram.gz
> - isolinux.bin
> - kernel.img
> - ldlinux.c32
> - syslinux.cfg
>
> Obviously this would be booted by SysLinux MBR, so I've changed
> isolinux.bin for syslinux.c32 (from /usr/lib/syslinux/modules/bios).
> Now rEFInd show a new "Legacy OS" entry pointing to the USB "whole
> device". Now I should be able to boot on Legacy OS mode, but it didn't
> worked.
>
> 3. Created a /EFI/boot folder and put there the files syslinux.efi
> (from /usr/lib/SYSLINUX.EFi/efi64) and ldlinux.e64 (from
> /usr/lib/syslinux/modules/efi64). Didn't worked.
>
> 4. Renamed /EFI/boot/syslinux.efi to /EFI/boot/bootx64.efi. Didn't worked.
>
> 5. Set the esp flag on the partition. Now rEFInd show two entries, one
> for the Legacy OS and a new one for "Default fallback loader on 32 MiB
> device". Executing it, it loads the kernel and the initram but didn't
> loaded.
>
> 6. Renamed back /EFI/boot/bootx64.efi to /EFI/boot/syslinux.efi, just
> to be sure. The "Default fallback loader on 32 MiB device" entry has
> changed to "Syslinux on 32 MiB device". Executing it, it loads the
> kernel and the initram but didn't loaded.
>
> 7. Moved /EFI/boot/syslinux.efi and /EFI/boot/ldlinux.e64 to root
> folder of the partition, so now the files in the root partition are:
>
> - initram.gz
> - kernel.img
> - ldlinux.c32
> - ldlinux.e64
> - syslinux.c32
> - syslinux.cfg
> - syslinux.efi
>
> The "Syslinux on 32 MiB device" entry is still there, so the theory
> that "syslinux" is hardcoded somewhere (the MBR code?) and the
> executable is searched in the partition the same way it happens with
> the syslinux.cfg file makes sense. Executing it, it loads the kernel
> and the initram but didn't loaded.
>
> So my conclusions are:
>
> 1. Just by having a MBR (and an active partition?) the Legacy OS
> appear, but it's not working on my MacBook while it does on my PCs.
> Maybe the MBR code is not being executed? Maybe it needs something on
> the partition boot sector?
> 2. EFI option only appear when a partition has the esp flag. Probably
> related, with the esp flag the partition is NOT automounted on my
> Ubuntu machine, I need to mount it by hand using the "mount" command.
> 3. The /EFI/boot/bootx64.efi path is the fallback one, but not
> necesarily the one needed to boot. In fact, my Ubuntu system on the
> MacBook doesn't have it (and it boot using EFI...).
> 4. The syslinux.efi executable is searched on the EFI partition, at
> least from /EFI/boot to /EFI to / the same way that happens with the
> syslinux.cfg file (that it was always on the root folder of the
> partition).
>
> The most annoying thing (to me) is that it doesn't boot at all on
> Legacy OS mode (MBR), while it should... :-/
>

After the previous mail I found the syslinux.sys was not between the files,
so I tested the USB drive on my PC and didn't work, saying that's not a
bootable image. I used the installed and it added it, so now it worked on
my PC again, but not in the Mac. Only thing, rEFInd now it says "Linux on
32 MiB device" instead of "Legacy OS on 32 MiB device"... it's something!
:-) But anyway, on Legacy OS mode it still don't boot and on EFI it sill
load the kernel and the initramfs but doesn't boot, too. I've added some
screenshots so you can see the output messages.


----- End forwarded message -----


Groeten
Geert Stappers
one the moderators of the Syslinux mailinglist
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