6I25 --recover

Well that brings up some strangeness of this install
It doesn't have lspci.
a search in Synaptic package manager shows no results for it.

Do you know what library it might be hiding in?

Thank you for that Tommy!

Here are the results:
Without the 6i25 card installed:
00:00.0 Host bridge: Intel Corporation 8th Gen Core 4-core Desktop Processor Host Bridge/DRAM Registers [Coffee Lake S] (rev 08)
00:02.0 VGA compatible controller: Intel Corporation 8th Gen Core Processor Gaussian Mixture Model
00:14.0 USB controller: Intel Corporation 200 Series/Z370 Chipset Family USB 3.0 xHCI Controller
00:16.0 Communication controller: Intel Corporation 200 Series PCH CSME HECI
00:17.0 SATA controller: Intel Corporation 200 Series PCH SATA controller [AHCI mode]
00:1c.0 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port (rev f0)
00:1d.0 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port (rev f0)
00:1d.3 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port (rev f0)
00:1f.0 ISA bridge: Intel Corporation Device a2ca
00:1f.2 Memory controller: Intel Corporation 200 Series/Z370 Chipset Family Power Management Controller
00:1f.4 SMBus: Intel Corporation 200 Series/Z370 Chipset Family SMBus Controller
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 15)


With the 6i25 installed:
00:00.0 Host bridge: Intel Corporation 8th Gen Core 4-core Desktop Processor Host Bridge/DRAM Registers [Coffee Lake S] (rev 08)
00:01.0 PCI bridge: Intel Corporation Skylake PCIe Controller (x16) (rev 08)
00:02.0 VGA compatible controller: Intel Corporation 8th Gen Core Processor Gaussian Mixture Model
00:14.0 USB controller: Intel Corporation 200 Series/Z370 Chipset Family USB 3.0 xHCI Controller
00:16.0 Communication controller: Intel Corporation 200 Series PCH CSME HECI
00:17.0 SATA controller: Intel Corporation 200 Series PCH SATA controller [AHCI mode]
00:1c.0 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port (rev f0)
00:1d.0 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port (rev f0)
00:1d.3 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port (rev f0)
00:1f.0 ISA bridge: Intel Corporation Device a2ca
00:1f.2 Memory controller: Intel Corporation 200 Series/Z370 Chipset Family Power Management Controller
00:1f.4 SMBus: Intel Corporation 200 Series/Z370 Chipset Family SMBus Controller
01:00.0 PCI bridge: Texas Instruments XIO2001 PCI Express-to-PCI Bridge
02:00.0 DPIO module: Device 2718:5125 (rev 01)
05:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 15)

I still am not understanding why the ethernet controller stops working with the card installed.

I downloaded the mesaflash from GitHub & compiled.
It behaves very much better! It now shows me there is firmware on the card & I verified it to the .bit file I have, and it matches!

Still having issues with the ethernet port with the 6i25 installed.

Digging some more.

Can you try:

lspci -vv


It look to me like the BIOs has messed up the Ethernet slot information
somehow thinking that its behind the 6I25s bridge

I seem to have gotten the ethernet port to work with the 6i25 card installed.
While the card was out, I forced NetworkManager to write out the ethernet scripts.
Put the card back in the machine, and now works. Not the first time NetworkManager has burned me.

Attached are the lspci dumps

With PCIE motherboards, control over IRQs is pretty much gone, since it is no longer hardware bound, and virtualized in the chipset.

Please correct me if that is wrong, with some examples.

That was the beauty of the PCI & PCIE busses. We got away form hardware interrupts! The Bus Mastering system eliminated all that grief.

The motherboard I am working with is a mini ITX, with an Intel i3 processor with internal GPU, one PCIE-16 slot. The board has an M2 socket that can work in a SATA mode for an SSD, or PCIE mode for another expansion card. A second M2 socket is set up for a WI-FI/Bluetooth card.
The only BIOS configurable IRQ is for the RS-232 port, which is a legacy interface.

The systems I care for @ work are high end workstations, with a PCIE expansion box that adds 8 more 16 lane PCIE slots, that are stuffed with high end nVidia GPUs. They all pick up IRQs from the bus mastering system, and pretty much never have a conflict.