Links to instructions for installing TrueNAS with front panel display capability on some ReadyNAS

Quick update, and thanks to you both. That was fast work.

Sandshark, your 528X/628X probes settled it. Pentium D1508 and Xeon D-1521 confirmed, C224 chipset, none of the hardware my LCD code talks to. So my README was wrong and I've now fixed it: the driver is for the RN426/428 only. The good news in your output is the dmesg lines showing the stock kernel drives the front panel through gpio_ich, with the button interrupt on gpio_ich line 2. That's the map I need for a proper 52x/62x port.

portalman, your GRML probes explained themselves once I checked: Debian stopped building the gpio-ich module entirely, in both current releases. Your modprobe didn't fail because of anything on your end, the module doesn't exist. TrueNAS and OMV use Debian kernels, so the same applies there.

That kills my "load the module and use libgpiod" plan, but there's a cleaner route anyway: the ICH GPIO block sits on plain I/O ports, so a driver can talk to it directly through /dev/port with no kernel module at all. That's how my RN426 code already works, and it would run the same on OS6, GRML, TrueNAS or OMV. That's the direction I'll take for the 52x/62x port, and possibly the 516 after that.

No need to run anything else for now. When I have code worth testing I'll say so here.