From ea4f248945f195c3fb9038a02218be1d4ce19ee7 Mon Sep 17 00:00:00 2001
From: Eric Fahlgren <ericfahlgren@gmail.com>
Date: Mon, 24 Aug 2026 10:23:34 -0700
Subject: [PATCH] system: provide missing image type information

An ongoing chronic pain point when performing upgrades is determining
which of several images is the correct one.  For most devices,
this is a simple choice between "factory" or "sysupgrade", with the
latter being the correct choice.  On several targets, the choice
is not so obvious.

For example, on the x86/64 target, we have "combined" and
"combined-efi" images, and users must somehow determine which is
appropriate.  The armsr and loongarch devices are simpler with only
"combined-efi", and tegra only has "sdcard".  On the ramips/mt7621
target there are five Mikrotik devices that have both "sysupgrade"
and "sysupgrade-v7".  Further, the new spacemit/k1 target has three:
"sdcard", "emmc" and "other".

Note that although much of this deals with automated systems (ASU),
it will also benefit manual upgrades by providing the user with
needed information from a reliable source.

Since there is currently no way to determine which image is installed
on-device, we are adding a new mechanism to allow per-target
definition of that data and exposing it through the system board call.

On-device generation of "/tmp/sysinfo/image_type" contents is left
open so as to allow flexibility of implementation.

Details
-------
To illustrate the selection mechanism, we'll provide an example
taken from ath79/generic/profiles.json.  This is a minimized snippet,
all "images" entries are retained, but unrelated field values have
been deleted.

  {
    "profiles": {
      "tplink_archer-c7-v4": {
        "images": [
          {
            "filesystem": "squashfs",
            "name": "openwrt-ath79-generic-tplink_archer-c7-v4-squashfs-sysupgrade.bin",
            "type": "sysupgrade"
          },
          {
            "filesystem": "initramfs",
            "name": "openwrt-ath79-generic-tplink_archer-c7-v4-initramfs-kernel.bin",
            "type": "kernel"
          },
          {
            "filesystem": "squashfs",
            "name": "openwrt-ath79-generic-tplink_archer-c7-v4-squashfs-factory.bin",
            "type": "factory"
          }
        ]
      }
    }
  }

Currently we can derive two of the three keys easily:

  ubus call system board | \
    jsonfilter -e 'profile=$.board_name' \
               -e 'filesystem=$.rootfs_type'

Then image selection becomes

  profiles[$profile].images[@.filesystem = $filesystem && @.type = "sysupgrade"]

For most targets, guessing that the profile's image type is
'sysupgrade' works, but for quite a few it fails.

Examples from x86/64 and spacemit/generic, in both we've omitted
many sections and fields to focus on the issue at hand:

  "images": [
    {
      "filesystem": "squashfs",
      "name": "openwrt-x86-64-generic-squashfs-combined.img.gz",
      "type": "combined"
    },
    {
      "filesystem": "squashfs",
      "name": "openwrt-x86-64-generic-squashfs-combined-efi.img.gz",
      "type": "combined-efi"
    }
  ]

  "images": [
    {
      "filesystem": "erofs",
      "name": "openwrt-spacemit-k1-generic-erofs-other.img.gz",
      "type": "other"
    },
    {
      "filesystem": "erofs",
      "name": "openwrt-spacemit-k1-generic-erofs-emmc.img.gz",
      "type": "emmc"
    },
    {
      "filesystem": "erofs",
      "name": "openwrt-spacemit-k1-generic-erofs-sdcard.img.gz",
      "type": "sdcard"
    }
  ]

Link: https://github.com/efahl/owut/issues/68
Link: https://github.com/openwrt/openwrt/pull/23231#issuecomment-5386675525
Signed-off-by: Eric Fahlgren <ericfahlgren@gmail.com>
---
 system.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/system.c b/system.c
index f6fe444..f748e6f 100644
--- a/system.c
+++ b/system.c
@@ -251,6 +251,22 @@ static int system_board(struct ubus_context *ctx, struct ubus_object *obj,
 	if (rootfs_type)
 		blobmsg_add_string(&b, "rootfs_type", rootfs_type);
 
+	if ((f = fopen("/tmp/sysinfo/image_type", "r")) != NULL)
+	{
+		/* Strictly optional, don't try to guess if it is
+		 * not explicit.
+		 */
+		if (fgets(line, sizeof(line), f))
+		{
+			val = strtok(line, "\t\n");
+
+			if (val)
+				blobmsg_add_string(&b, "image_type", val);
+		}
+
+		fclose(f);
+	}
+
 	if ((f = fopen("/usr/lib/os-release", "r")) != NULL)
 	{
 		c = blobmsg_open_table(&b, "release");