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The XGS 126 and 136's status light, lit once the appliance is up, 2026-10-27

735: under OPNsense the status light on the front of an XGS 126 blinked for as long as the appliance ran. The vendor's appliance table, which its installer images carry, gives each model a STATUS_LED field. For the XGS 126 and 136 it is I2C, in the installer images of vendor versions 21, 22 and 23 alike: the light is two registers of the board's controller at slave 0x40 on the host's SMBus - 0xf2 the green, 0xf3 the red, each 0x01 lit, 0x51 blinking and 0x00 dark; a blinking one can read back as 0x29. The board's own start leaves the green blinking, and the vendor's software lights it at the end of its boot. Under OPNsense nothing did. (The XGS 3300's field is NO: the vendor's software never sets that one.)

Read, then lit

tools/statusled/xgs-statusled.c reads the two registers through the host's auxiliary SMBus controller, the AMD FCH's second PIIX4-style block at I/O 0x0b20. It writes those two registers and those three values only - the same controller holds other registers, a factory-reset flag among them - and before writing anything it reads 0xf2: on a bus where nothing answers, it writes nothing. Built on the first XGS 3300, the build box, with -Wall -Wextra -Werror, and run by images/deploy/lab-735-statusled.sh:

The XGS 136, board 201, vendor version 21: the green blinking (0x29) and the red dark before; lit green; read back lit two seconds later. The first XGS 3300, board 202: no controller at 0x40 on that bus, nothing written

On the XGS 136 (board 201, vendor version 21) the green read blinking (0x29) and the red dark: what an owner's XGS 126 showed. Lit green, it read lit (0x01) two seconds later. On the first XGS 3300 (board 202), where nothing answers at 0x40 on that bus, the tool refused and wrote nothing.

At every boot

install.sh builds the tool on board 201 only, with the appliance's own cc as it does the XGS 3300's sensor tool, and lights the light. The start hook 70-xgs-statusled lights it again at the end of every boot; it asks board.sh, and does nothing on any other board. The XGS 136 with this change installed by install.sh, the light set blinking (0x51), then restarted (images/deploy/lab-735-boot.sh):

The XGS 136 restarted at 17:51:30 after its light was set blinking: the start hook xgs-statusled run 79 s into the boot, the light read lit green (0x01), the tool and the hook installed

The hook ran 79 s into the boot, and the light read lit (0x01).

Not done

  • An XGS 126 was not run. It has the same board (201) and the same table entry as the XGS 136, so the same registers; there is no XGS 126 in the lab.
  • Other models are left alone. The table drives the 87, 88, 107 and 108's lights through the host's GPIO, and the 118 and 128's through their embedded controller; neither is this change's.
  • XGS: Overview does not show the light yet.

Discussion

The discussion of this page is held in the project's GitHub Discussions. Showing it here loads giscus from giscus.app and GitHub, and writing in it needs a GitHub account - what that means.