Welcome to the forums.
First, please note that vague questions like these are likely to result in low-quality responses that are not particularly helpful. You have posted a question along the lines of "my vehicle won't start". We don't know if you've got a car, truck, motorcycle, airplane, helicopter, or bicycle, or whether it's fueled by gasonline, diesel, hydrogen, or electric battery. The lack of any relevant detail makes this extremely hard to come up with good answers.
As a result, and as required by the Forum Rules, conveniently linked at the top of every page in red, we ask that you post a reasonably detailed hardware manifest of your system, versions of both Proxmox and TrueNAS involved, etc. For the hardware manifest, we don't usually need detail down to the exact brands, but telling us that you have a Supermicro X10SRL with an E5-1650v3 along with 4x 16GB sticks of DDR4-2400 ECC, etc.
Some general points here in response to your vague question:
Proxmox has not proven itself to be a reliably stable hypervisor platform for FreeNAS/TrueNAS. It is a new entrant into the hypervisor game and its PCIe passthru is still in the "experimental" stage. See this wiki:
pve.proxmox.com
where it says
"PCI passthrough is an experimental feature in Proxmox VE"
It's recommended that you follow the guidance in
[---- 2018/02/27: This is still as relevant as ever. As PCIe-Passthru has matured, fewer problems are reported. I've updated some specific things known to be problematic ----] [---- 2014/12/24: Note, there is another post discussing how to deploy a small FreeNAS VM instance for basic file...
www.truenas.com
for proper virtualization.
Version 16.00.00.00 (2017.05.02)
This is the wrong firmware version, although to me it looks like you just typed "sas3flash" without any arguments, so that's the version of the flash utility, not the card.
Please make sure you have installed 16.00.12.00 on the card.
Hey Community, If you are using an LSI 9300 HBA with FreeNAS or the soon-to-be TrueNAS CORE, you may experience some performance issues causing the controller to reset when using SATA HDDs. After working with Broadcom, we’ve come up with a...
www.truenas.com
So the question is, if the HBA is also in IT-Mode, if 'rombar=0'?
And is it important for TrueNAS to see the whole firmware (rombar=1)?
This is ambiguous. It looks to me like what may be happening is that the PC BIOS ROM portion of things is barfing. There is ALSO a thing called the firmware, which is the program that runs ON the HBA's CPU to provide all the I/O capabilities. Both things can be referred to as "firmware". The card firmware is probably running just fine.
You can check the firmware version of the card by running "sas3flash -list" and looking in the output.
Code:
# sas3flash -list
Avago Technologies SAS3 Flash Utility
Version 16.00.00.00 (2017.05.02)
Copyright 2008-2017 Avago Technologies. All rights reserved.
Adapter Selected is a Avago SAS: SAS3008(C0)
Controller Number : 0
Controller : SAS3008(C0)
PCI Address : 00:03:00:00
SAS Address : 5003528-0-2ab1-eb01
NVDATA Version (Default) : 0e.01.30.28
NVDATA Version (Persistent) : 0e.01.30.28
Firmware Product ID : 0x2221 (IT)
Firmware Version : 16.00.10.00
NVDATA Vendor : LSI
NVDATA Product ID : LSI3008-IT
BIOS Version : 08.37.00.00
UEFI BSD Version : 18.00.00.00
FCODE Version : N/A
Board Name : LSI3008-IT
Board Assembly : N/A
Board Tracer Number : N/A
Finished Processing Commands Successfully.
Exiting SAS3Flash.
The card CPU firmware MUST be running in order for the HBA to work. I suspect that what's broken for you is the PC BIOS firmware, which may be broken because you're using a dodgy hypervisor, or passthru is broken in some manner.