tl; dr; eventual success but it turned out (as expected) that the efforts were useless.
A little learning came out of it though.
Plop is mostly a waste of time. I made plop 5 running off MBR. It has a script to install it there from windows. It hung though when trying to search USB no matter the USB options set in the setup.
Also it initially starts with a black screen untul Ctrl+PgDown was used to change resolution. btw this stupid compaq doesn't seem to support normal VESA modes as anything but the standard console mode made it turn black. See below.
Then I setup PXE boot on my OpenWRT router according to the
OpenWRT wiki. And put there all plop version (5, 6 and plopkexec). This is the pxe config I ended up with
Code:
DEFAULT Debian
# DEFAULT vesamenu.c32
PROMPT 1
TIMEOUT 80
MENU TITLE OpenWrt PXE-Boot Menu
label Debian
MENU LABEL Debian x86
KERNEL disks/deb-netinst-x86/install.386/vmlinuz
APPEND netboot=nfs nfsroot=192.168.1.1:/mnt/extstorage/tftp/disks/deb-netinst-x86/ initrd=disks/deb-netinst-x86/install.386/gtk/initrd.gz
TEXT HELP
Starts the Debian Netinst CD
ENDTEXT
label plop6
MENU LABEL Plop Boot Manager 6
KERNEL pbm6
label plopkexec
MENU LABEL PlopKExec Boot Manager
KERNEL plopkexec
label plop5
MENU LABEL Plop Boot Manager
KERNEL plpbt.bin
Keep in mind `DEFAULT Debian` is probably incorrect because boot ended up in the boot prompt. So I had to type `plop5` or whatever other label to actually start them.
On the compaq plop5 couldn't be started for some reason, plopkexec crashed with some kernel errors and plop6 got stuck while loading USB drivers. So no luck at all. I decided to try network boot on an old core 2 duo PC I had in storage as well. On it plop 5 and 6 didn't want to start and plopkexec worked to a point. It detected the USB but then computer rebooted when attempting to boot.
So that was about plop, no good at all.
One more point about pxelinux is that `vesamenu.c32` worked well on the core 2 duo PC but it resulted in a black screen on the compaq. I could select an option with the keyboard though and run it, just knowing what to do on memory.
So the next option was to try staging startup of the debian installer (the only solid remaining i386 distro I think). So I ended up with the `Debian` entry above, where I copied the files from the install flash drive to the tftp root. It was just substituting ubuntu config from OpenWRT wiki with the files I saw on Debian install drive.
I also tried to add the `vga=788` option that I saw in debian install flash drive grub.cfg but it resulted in a black screen on the compaq (while it worked for the core 2 duo PC.
Anyway, that `Debian` entry booted and installer reached the mount installation media step, where it failed. Either my OpenWRT server didn't work out or maybe I didn't setup the boot entry properly for Debian. Maybe it could be fixed by looking at the
debian PXE install howto (that I didn't do).
I had the brilliant at this point to connect the installation USB media and ask installer to try again scan for installation media. And it recognized it! (although on the compaq the installer started in console mode, not the graphical mode).
Now finally happy and satisfied, I started the install. While installing packages though, the disk drive started to produce super strange screeching noises. I looked at the logs and saw some failed ata commands. installer soon failed, apparently the disk drive is defective or it requires some special workarounds. But that was enough for me. The old s*&^t goes to the trash.