Preventing automatic driver loading on live boot disk

[Vadim Lebedev <vadiml1024@xxxxxxxxx>]

I'm preparing ubuntu-based live boot disk. It works fine mostly, but on some machines equipped with Nvidia Quadro cards the default nouveau driver causes problems (temporary freezes). I've determined that buy blacklisting nouveau driver (in /etc/modprobe.d/blacklist.conf) I can fix the problem. However this approach inhibits nouveau driver for every nvidia equipped machine which is an overkill. Of course, i can detect the presence of the Quadro card after the boot, blacklist it, do update-initramfs -u and reboot but this approach modifies live boot disk and I would like to avoid that. I wonder if there is a way to detect the presence of nvidia Quadro somewhere very early in the boot sequence and prevent loading of the offending driver and fall back to standard VESA driver.

I've tried too create a service file:
[Unit]
Description=Disable Nouveau driver
DefaultDependencies=no
Before=kmod.service


[Service]
Type=oneshot
ExecStart=/usr/bin/ocd-blacklist-nouveau.sh

========================
and the shell script

#!/bin/bash
set -x
if /usr/bin/lspci | /usr/bin/grep Quadro >/dev/null; then
   /usr/bin/logger Found Nvidia Quadro device. Disabling Nouveau driver
   echo blacklist nouveau >/etc/modprobe.d/blacklist-nouveau.conf
else
   rm -f /etc/modprobe.d/blacklist-nouveau.conf
fi

But it seems that the service is not executed...

Any ideas, please?