Syslinux - Jul 2020 - extlinux - Failed to load ldlinux.c32

Hello there

I built development version of syslinux from git 6.04-pre3-3-(sometag) 
and I am trying to boot a slackware-current system with it.  I do not 
use a separated partition for `/boot`.  It's just `/dev/sda1` here for 
`/` and `/boot` is just a folder.  I simply use `mbr.bin` against a DOS 
partition table and the first partition having the bootable flag.

With this layout, the only way I manage to get syslinux/extlinux up and 
running, has always been to use `/` as installation directory.

         extlinux --install /

When ever I try one of the following

         extlinux --install /boot
or

         extlinux --install /boot/syslinux

the boot process fails to find `ldlinux.c32`.

Is this a known problem?  A I doing something wrong?  Why can't I use 
`/boot` or `/boot/syslinux` instead of `/`?

It's not a very big issue, as I just use `/` as a workaround, but I feel 
this prevents syslinux/extlinux to be used as a default bootloader for 
distros that would consider it as an alternative to LILO or GRUB.  One 
usually wants things to be in `/boot` on GNU/Linux, though the UNIX 
tradition rather let's the kernel live in `/`.

Thanks
-- 
Pierre-Philipp

> I built development version of syslinux from git 6.04-pre3-3-(sometag)
> and I am trying to boot a slackware-current system with it.  I do not
> use a separated partition for `/boot`.  It's just `/dev/sda1` here for
> `/` and `/boot` is just a folder.  I simply use `mbr.bin` against a DOS
> partition table and the first partition having the bootable flag.
> 
> With this layout, the only way I manage to get syslinux/extlinux up and
> running, has always been to use `/` as installation directory.
> 
>          extlinux --install /
> 
> When ever I try one of the following
> 
>          extlinux --install /boot
> or
> 
>          extlinux --install /boot/syslinux
> 
> the boot process fails to find `ldlinux.c32`.
> 
> Is this a known problem?  A I doing something wrong?  Why can't I use
> `/boot` or `/boot/syslinux` instead of `/`?
 
 
Please try 6.04-pre1. FWIW, official binaries from 6.04-pre2 and pre3 
_will_ fail.

I would suggest trying first the official binaries that are already 
included in the official distribution archive (6.03-pre1). Let me 
emphasize: first test official binaries, not your own build.

If the official binaries fail, I would then suggest testing with the 
binaries from Debian Sid.

Only as a last resort, try you own build. Please be aware that there 
are some building issues ATM.

In any case, _avoid_ mixing binaries from different versions / builds 
(e.g. c32 modules from one version with the installer from another; 
that's a "no-no").

BTW, I would also suggest searching the official Syslinux wiki.

Regards,
Ady.

Thank you for your answer.  I need to correct some information from my 
previous post: booting from `/` did not work either.  I just assumed it 
did based on previous experience.  But with that successful build on 
development branch, it did not either.
> I would suggest trying first the official binaries that are already
> included in the official distribution archive (6.03-pre1). Let me
> emphasize: first test official binaries, not your own build.
I do not succeed building 6.03 nor 6.04-pre1 on slackware current with 
GCC 9 anyway.  This is why I was using the development branch.

v6.04-pre1 make install and installers were complaining so I used its 
binaries right away as such (I tried both / and /boot/syslinux/)

         dd if=./bios/mbr/mbr.bin of=/dev/sda
         ./bios/extlinux/extlinux --install /
         cp -f ./bios/com32/lib/libcom32.c32 /
         cp -f ./bios/com32/mboot/mboot.c32 /

but in the end I got the same error as previously:

	Failed to load ldlinux.c32

Thanks
-- 
Pierre-Philipp

> If the official binaries fail, I would then suggest testing with the
> binaries from Debian Sid.
I finally tried building syslinux with the patches I got from Debian and it
worked.

https://sources.debian.org/patches/syslinux/
--> and chose those against 6.03 so I don't need to play with GIT tags.
https://sources.debian.org/patches/syslinux/3:6.03+dfsg-14.1+deb9u1/

For the record

- 6.03 build --> coulnt build on slackware-current
- 6.03 binaries --> Failed to load ldlinux.c32
- 6.03 debian patched build --> works!
- 6.04-pre1 binaries --> Failed to load ldlinux.c32
- 6.04 git build --> Failed to load ldlinux.c32

Didier, when it works, SYSLINUX is in fact easier than GRUB.  What a nice syntax
we have there!  And the bootcode install process is not particularly hard
either.

Oh and for my originating question on `/` vs `/boot/booting` on a single root
partition, it's also solved.  I now host the second stage bootcode in
`/boot/syslinux` without an issue.

        dd if=./bios/mbr/mbr.bin of=/dev/sda
        ./bios/extlinux/extlinux --install /boot/syslinux/
        cp -f ./bios/com32/lib/libcom32.c32 /boot/sysliunx/
        cp -f ./bios/com32/mboot/mboot.c32 /boot/syslinux/

and if one also wants the menu to show up, `libutil.c32` and `menu.c32`.

	vi /boot/syslinux/syslinux.cfg

	default XEN
	prompt 1
	timeout 50

	label Linux
        	linux /boot/vmlinuz
       		append root=/dev/sda1 ro vt.default_utf8=0 mitigations=off vga=791
        #initrd=/boot/initrd.img

	label XEN
        	kernel mboot.c32
        	append /boot/xen.gz dom0=pvh dom0_mem=1024M,max:8192M loglvl=info
noreboot=true --- /boot/vmlinuz console=tty0 root=/dev/sda1 ro vt.default_utf8=0
mitigations=off vga=791
        	#pv-linear-pt=true
        	#--- /boot/initrd.img

Thank you both for your support
-- 
Pierre-Philipp