OpenWrt/LEDE Project

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  • Task Type Bug Report
  • Category Base system
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  • Operating System All
  • Severity Medium
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Attached to Project: OpenWrt/LEDE Project
Opened by nwf - 06.09.2020

FS#3324 - Zyxel EMG2926-Q10A (aka NBG6716) requires changes in tree

459c8c9ef816156107e297964d088ddee2b4eef5 added support for the Zyxel NBG6716 device. Unfortunately, I believe it made an error in the partition layout. Because the RAS image header is written to flash, the offsets for sub-partitions of firmware must be shifted down by the size of this header (i.e., 128KiB):

diff --git a/target/linux/ath79/dts/qca9558_zyxel_nbg6716.dts b/target/linux/ath79/dts/qca9558_zyxel_nbg6716.dts                                            
index 90328078dd..148a6ea2d1 100644
--- a/target/linux/ath79/dts/qca9558_zyxel_nbg6716.dts
+++ b/target/linux/ath79/dts/qca9558_zyxel_nbg6716.dts
@@ -148,14 +148,19 @@
                        reg = <0x500000 0x7b00000>;
                };

-               partition@500000 {
+               // There's a RAS image header inside the firmware partition,
+               // taking up one erase block (128KiB), so the kernel and ubi
+               // partitions are shifted by that amount.
+
+               partition@520000 {
+                       // JFFS2 containing the compressed kernel
                        label = "kernel";
-                       reg = <0x500000 0x400000>;
+                       reg = <0x520000 0x400000>;
                };

-               partition@900000 {
+               partition@920000 {
                        label = "ubi";
-                       reg = <0x900000 0x7700000>;
+                       reg = <0x920000 0x76C0000>;
                };
        };
 };

Without this change, the bootloader finds the kernel inside its JFFS2 partition just fine, but then the kernel dies when it cannot find the UBI header at the indicated offset.

It is not clear to me whether this change should be applied to all NBG6716-equivalent devices or merely the one I have in hand.

Speaking of, that device calls itself a AAVK-EMG2926Q10A in its RAS header and refuses to flash anything not so labeled. Therefore, I have added a target for it by lightly extending the existing one:

diff --git a/target/linux/ath79/dts/qca9558_zyxel_aavk-emg2926q10a.dts b/target/linux/ath79/dts/qca9558_zyxel_aavk-emg2926q10a.dts                          
new file mode 100644
index 0000000000..ec94aa0d73
--- /dev/null
+++ b/target/linux/ath79/dts/qca9558_zyxel_aavk-emg2926q10a.dts
@@ -0,0 +1,2 @@
+/* This is just an alias, really */
+#include "qca9558_zyxel_nbg6716.dts"
diff --git a/target/linux/ath79/image/nand.mk b/target/linux/ath79/image/nand.mk                                                                            
index ad79c487ad..7336dc45d7 100644
--- a/target/linux/ath79/image/nand.mk
+++ b/target/linux/ath79/image/nand.mk
@@ -263,3 +263,9 @@ define Device/zyxel_nbg6716
   UBINIZE_OPTS := -E 5
 endef
 TARGET_DEVICES += zyxel_nbg6716
+
+define Device/zyxel_aavk-emg2926q10a
+  $(call Device/zyxel_nbg6716)
+  RAS_BOARD := AAVK-EMG2926Q10A
+endef
+TARGET_DEVICES += zyxel_aavk-emg2926q10a

A commented on 17.08.2021 18:26

I can confirm - I have Zyxel NBG6716 with 256MB flash and it's not possible to flash 21.02 on the device - it bootlops:

[    7.134014] ubi0: user volume: 0, internal volumes: 1, max. volumes count: 128
[    7.141345] ubi0: max/mean erase counter: 2/1, WL threshold: 4096, image sequence number: 97628008
[    7.150435] ubi0: available PEBs: 1948, total reserved PEBs: 43, PEBs reserved for bad PEB handling: 39
[    7.159989] hctosys: unable to open rtc device (rtc0)
[    7.165200] ubi0: background thread "ubi_bgt0d" started, PID 368
[    7.171602] VFS: Cannot open root device "(null)" or unknown-block(0,0): error -6
[    7.179227] Please append a correct "root=" boot option; here are the available partitions:
[    7.187711] 1f00             256 mtdblock0
[    7.187715]  (driver?)
[    7.194341] 1f01              64 mtdblock1
[    7.194344]  (driver?)
[    7.200986] 1f02              64 mtdblock2
[    7.200989]  (driver?)
[    7.207632] 1f03           16000 mtdblock3
[    7.207635]  (driver?)
[    7.214263] 1f04            2048 mtdblock4
[    7.214266]  (driver?)
[    7.220900] 1f05            2048 mtdblock5
[    7.220903]  (driver?)
[    7.227546] 1f06            1024 mtdblock6
[    7.227549]  (driver?)
[    7.234178] 1f07            2048 mtdblock7
[    7.234181]  (driver?)
[    7.240815] 1f08          254976 mtdblock8
[    7.240818]  (driver?)
[    7.247459] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[    7.256820] Rebooting in 1 seconds.. 
Admin
john commented on 17.08.2021 18:29

full boot log plz, does it work with the patch pasted above ? if so kindly post the patch on openwrt-devel

A commented on 17.08.2021 18:33

I don't have oppoturnity right now to have bootlog again (I need that hardware working) and I don't have option to test out the patch (as I don't have knowledge and tools needed to compile that).

If firmware with patch provided, I can test it later on and provide bootlog.

A commented on 17.08.2021 21:14

Thanks to local openwrt forum user I was able to test firmware compiled with patch (nbg6716) and it works flawlessly.

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