FS#3971 - Zyxel nbg-419v2 bootloop

[openwrt-bot]

diego0815:

after upgrading my zyxel nbg-419v2 to 2021.02RC4 i noticed a bootloop

when connecting the serial cable it turned out to be a kernel unpacking issue:

raspi_read: from:50000 len:40
. Image Name: MIPS OpenWrt Linux-5.4.137
Created: 2021-07-31 17:21:01 UTC
Image Type: MIPS Linux Kernel Image (lzma compressed)
Data Size: 1496161 Bytes = 1.4 MB
Load Address: 80000000
Entry Point: 80000000
raspi_read: from:50040 len:16d461
....................... Verifying Checksum ... OK
Uncompressing Kernel Image ... LZMA ERROR 1 - must RESET board to recover

U-Boot 1.1.3 (Jun 9 2012 - 07:23:11)

Board: Ralink APSoC DRAM: 64 MB
relocate_code Pointer at: 83fac000

---

Software System Reset Occurred

---

spi_wait_nsec: 3c
spi device id: c2 20 17 c2 20 (2017c220)
find flash: MX25L6405D


once i managed flashing 19.07.08 via tftp it works again as expected.

unfortunately [[https://openwrt.org/toh/zyxel/nbg-419n_v2#oem_installation_using_the_tftp_method|the wiki]] was more misleading than helping, especally the magic number is wrong, it seems the right one is already in the normal images, so changing makes things worse.

[openwrt-bot]

walterav1984:

Can you post the mtd partition sizes/layout, newer openwrt releases are to big for certain partitions of the layout altering them may fix it on some routers. See first 2 comments in this wifi bug but related topic:
https://bugs.openwrt.org/index.php?do=details&task_id=3906&string=zyxel

Sometimes loading from serial/tftp may bypass mtd restrictions.

Eventhough partition sizes may not be the problem it can be the bootloader itself which cannot load bigger files. This has also occurred on some routers but I can't find a recent example.

[openwrt-bot]

diego0815:

Oh really sorry, I completely forgot about this bug, now took my router out again after a long time and checked the mtd sizes:

root@OpenWrt:~# cat /proc/mtd
dev: size erasesize name
mtd0: 00030000 00001000 "u-boot"
mtd1: 00010000 00001000 "u-boot-env"
mtd2: 00010000 00001000 "factory"
mtd3: 007b0000 00001000 "firmware"
mtd4: 0014985f 00001000 "kernel"
mtd5: 006667a1 00001000 "rootfs"
mtd6: 00448000 00001000 "rootfs_data"


In the meantime I retired the router and replaced it with an nbg6617, so my urge to get this fixed has dropped slightly...