[syslinux] Extlinux no longer bootable, how to fix?

[Gene Cumm]

On Sun, Aug 4, 2019 at 6:13 PM Tong Sun via Syslinux
<syslinux at syslinux.org> wrote:
>
> Hi,
>
> I'm experiencing a strange problem, my extlinux is no longer bootable,
> and I'm wondering how to troubleshoot the problem for a fix.
>
> It's not just an one-off thing, but is happening to me all the time --
> I use extlinux to boot up all my linux, and it has always been working
> for me, for at least 10+ years. However recently I started to
> duplicate my linux system from partition to partition, from a
> carefully configured one, and from machine to machine as well.
>
> - during the mirror/transfer, I always exclude the
> /boot/extlinux/ldlinux.sys file

Presumably this is just a file copy and not duplicating things like
the VBR (the first sector of the file system/partition).

> - then after the transfer, I always do a extlinux install via
>
>     extlinux --install $new_os_mnt/boot/extlinux
>
> I think this should be enough, however, the strange problem is that it
> is not fully working:
>
> - its menu shows up fine but can’t boot /vmlinuz

In the context of your shell command, I assume this exists as
"$new_os_mnt/vmlinuz"?  Or did you really want to load
"$new_os_mnt/boot/extlinux/vmlinuz" and should have specified
"vmlinuz"?

> - after sellecting the menu, it shows “Loading /vmlinuz...” then
> flashed “failed”, and go back to the menu again.

What is "$new_os_mnt/vmlinuz"?  A real file or a symlink?

> Here is my extlinux menu:
>
> LABEL LU18R1
>         MENU LABEL LUbuntu ^Bionic
>         MENU DEFAULT
>         KERNEL /vmlinuz
>         APPEND initrd=/initrd.img
> root=UUID=ad26a5d8-a4ee-42d3-96aa-1f6f0eaa3968 ro net.ifnames=0 --
>
> - the same extlinux config works from the original mirroring source.
> - I've made sure the UUID is updated, thought I think it is irrelevant
> as it is the loading of /vmlinuz failed.
> - I.e., the real problem is loading the /vmlinuz from extlinux
>
> To confirm the situation, I've duplicate my linux system to at least
> three HD partitions, and none of them works. However, using the
> exactly same steps, when duplicate to my USB key, the system boots up
> beautifully. That's why I'm saying that it is a strange problem.
>
> If you are curious how I boot different linux from different partitions,
>
> - I have extlinux booted from the active partition,
> - then chain loading into different linux partitions
> - the linux system from the mirrored partitions boot up fine, as I can
> start them from Grub4dos. Moreover,
> - I Install & boot from grub2, and it is OK too. But I really don't
> like grub2, and would like to make extlinux work instead.
>
> All in all, the only problem is loading the /vmlinuz from extlinux, as
> the chainloading is fine, and the linux system itself boots up fine
> too. and I'm wondering how to troubleshoot the problem, and the fix
> too.
>
> Thanks

-- 
-Gene