[syslinux] Help! Extlinux no longer bootable after reorder disk numbers

[Tong Sun]

I split one partition, then my hard drive partitions and my partition
numbers are listed in the wrong order and I fixed them
<https://journalxtra.com/linux/how-to-reorder-linux-drive-partition-numbers/>
so
they run sequentially from lowest to highest.

And the problem is, as the article
<https://journalxtra.com/linux/how-to-reorder-linux-drive-partition-numbers/>
has
warned, my disks are "completely buggered" and none of my existing Ubuntu
systems can boot now. The Extlinux boot will complain something about:

requested disk number partition combination not found

If booting from Live CD, all the Ubuntu systems/partitions are still
mountable, no data have lost, but just none of them are bootable any more,
even after I reinstalled the extlinux boot to them (extlinux --install
/mnt/sdax/boot/extlinux), which is what I've been using before.

Now, details on how I boot my Ubuntu systems -- the active partition is a
Linux/Ubuntu system, that can still boot (from extlinux, because it resides
before the reordered partitions), and it in turn chain boots other Ubuntu
systems, with

  KERNEL chain.c32
  APPEND hd0 x

Judging from the extlinux above boot error message, it looks to me that the
chain boot is not working properly -- as if it still have an old copy of
the partitions' mapping, but this is only a wild guess.

my system:

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.1 LTS
Release:        18.04
Codename:       bionic

Is it still possible to get my Ubuntu systems booted?


Thanks a lot!