How can I pass kernel arguments via PXE to an Ubuntu-like OS installer ISO?

I'm in a tough situation in which I need to perform a remote installation of a QuantaStor (Ubuntu-based - hiss) appliance onto hardware with limited out-of-band access functionality.

The target system is an HP ProLiant DL180 G6 server, which has a fully-licensed Lights-Out LO100i remote KVM. This is a big step down from the ILO3 or ILO4 management processors. The challenge with this hardware is that the LO100i's virtual media functions are not reliable. As Java releases have progressed, this ILO has become less useful. Right now, I cannot get the system to boot via the remote media, even though this function worked well in the past.

So my next step was to attempt to PXE boot this server using the QuantaStor ISO image. Oddly, there are a number of conflicting accounts of how one can PXE boot an ISO image directly without chaining boot loaders, etc. After some experimentation, I found that I could boot an ISO using memdisk through the PXE server. I control the DNS and DHCP in this environment, so I went the standard route of modifying the /etc/dhcpd.conf configuration file to reflect:

# Begin temporary PXE boot
allow booting;
allow bootp;
option option-128 code 128 = string;
option option-129 code 129 = text;
next-server 172.30.27.5;
filename "/pxelinux.0";
# End temporary PXE boot

For my PXE config, I set /tftpboot/pxelinux.cfg/default to:

default menu.c32
prompt 0
timeout 300
ONTIMEOUT local

MENU TITLE PXE Menu

LABEL QuantaStor
        MENU LABEL QuantaStor
        KERNEL memdisk
        APPEND iso initrd=images/osn_quantastor_v3.8.2.5441.iso raw

Together, these features allowed me to get the system to begin booting the ISO. Unfortunately, the remote KVM's console produced the following garbled video output:

The appliance's installation screen should look like this:

Several reboots and after some basic research, I discovered that the LO100 remote KVM shares this framebuffer symptom with some Supermicro IPMI boards. The workaround is to pass vga16fb.modeset=0 to the boot arguments. This is unique to Ubuntu (sigh).

How can I get this statement into the argument line of the PXE-booted ISO?

Where should I add the statement?

Attempts to do so in the "APPEND" line of the /tftpboot/pxelinux.cfg/default don't seem to help. The Ubuntu hints suggest adding the line by pressing F6 at the ISO boot screen. My remote KVM is garbled by that point, and I'm not able to add it manually.

Any ideas?

Update:

I extracted the ISO and modified the isolinux.cfg file to change the installer's frame buffer support on the kernel APPEND line. The system boots and the installer appears to work... except I now receive an error about the CDROM. I'm assuming my PXE method is incorrect.

What is the proper way to use an ISO over PXE in this context?

Altering the append with desired parameters definitely won't help from PXELINUX in this setup, as the boot disk has its own ISOLINUX handling the kernel boot.

Two ways to fix this.

The simpler option: extract the ISO, modify the isolinux/isolinux.cfg file's append line with the needed boot arguments, re-pack the ISO. Have PXELINUX chain to the modified ISO.

The more complex (but possibly better, as it removes the chaining) option: instead of using memdisk to boot into the ISO, directly boot in the same way that the ISO's ISOLINUX would be doing.

Edit: clearer steps for booting to the OS within the ISO:

• Extract the ISO to /tftpboot/quantastore
• Copy the file preseed/quantastor.seed from the extracted ISO to the web root of an HTTP service running on your PXE server so that it's available at http://172.30.27.5/quantastor.seed

• Change your pxelinux.cfg/default file to boot directly to the extracted contents of the ISO. Remove the current LABEL QuantaStor and replace with:

  LABEL QuantaStor
    menu label QuantaStor
    kernel quantastor/install/vmlinuz
    append preseed/url=http://172.30.27.5/quantastor.seed locale=en_US.UTF-8 keyboard-configuration/layoutcode=us initrd=quantastor/install/initrd.gz ramdisk_size=16384 nodmraid acpi=off root=/dev/ram vga16fb.modeset=0 rw quiet
  

This should get a successful install for the most part, but the commands that QuantaStor runs at the end of the install will fail since they're looking directly for /cdrom. From the quantastor.seed file:

 d-i preseed/late_command string mkdir -p /target/lib/plymouth/themes/quantastor; \
 chroot /target echo "creating package dirs, setting up splash screens" >> /var/log/qs_install.log; \
 mkdir /target/qs-pkgs; \
 mkdir -p /target/qs-pkgs/drivers; \
 mkdir -p /target/opt/osnexus/quantastor/raid-tools; \
 cp /cdrom/finisher/raid-tools/* /target/opt/osnexus/quantastor/raid-tools; \
 cp /cdrom/finisher/deb/*.deb /target/qs-pkgs; \
 cp /cdrom/finisher/qs_preseed.sh /target/qs-pkgs; \
 cp /cdrom/finisher/drivers/* /target/qs-pkgs/drivers; \
 cp /cdrom/finisher/splash/* /target/lib/plymouth/themes/quantastor; \
 cp /cdrom/finisher/osnexus.gpg /target/qs-pkgs; \
 cp /cdrom/finisher/osnexus.list /target/etc/apt/sources.list.d/osnexus.list; \
 cp /cdrom/finisher/rc.local /target/etc/rc.local; \
 cp /cdrom/finisher/qs_runonce.sh /target/etc/qs_runonce.sh; \
 chroot /target /qs-pkgs/qs_preseed.sh

Probably just run that stuff manually after the install completes the first time around (removing the /target stuff) - if it's working other that that, we can adapt these commands to put their stuff in place without depending on the CD being in the drive.

Type it "blind"?

Hit Enter as soon as the (garbled) language selection appears, since it times out quickly.

Then tap F6, Esc, type in vga16fb.modeset=0 and press Enter.

You were probably missing the need to hit Esc right after F6.