lexxai:

Used TP-Link TL-WR841N/D v9 with mod 8M
tested with build for 8M firmware.

updated via:
scp copy to /tmp
mtd -r write /tmp/firmwaew.bin firmware

18.06 work ok on this hardware, report:[[https://lexxai.blogspot.com/2019/07/hardware-modding-tp-link-tl-wr841n-v9.html]].

[ 0.000000] Linux version 4.14.167 (builder@buildhost) (gcc version 7.5.0 (OpenWrt GCC 7.5.0 r10911-c155900f66)) #0 Wed Jan 29 16:05:35 2020
[ 0.000000] bootconsole [early0] enabled
[ 0.000000] CPU0 revision is: 00019374 (MIPS 24Kc)
[ 0.000000] MIPS: machine is TP-Link TL-WR841N/ND v9
[ 0.000000] SoC: Qualcomm Atheros QCA9533 ver 1 rev 1
[ 0.000000] Determined physical RAM map:
[ 0.000000] memory: 02000000 @ 00000000 (usable)
[ 0.000000] Initrd not found or empty - disabling initrd
[ 0.000000] Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
[ 0.000000] Primary data cache 32kB, 4-way, VIPT, cache aliases, linesize 32 bytes
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x0000000000000000-0x0000000001ffffff]
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000000000000-0x0000000001ffffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x0000000001ffffff]
[ 0.000000] random: get_random_bytes called from 0x804776ec with crng_init=0
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 8128
[ 0.000000] Kernel command line: console=ttyS0,115200n8 rootfstype=squashfs,jffs2
[ 0.000000] PID hash table entries: 128 (order: -3, 512 bytes)
[ 0.000000] Dentry cache hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.000000] Inode-cache hash table entries: 2048 (order: 1, 8192 bytes)
[ 0.000000] Writing ErrCtl register=00000000
[ 0.000000] Readback ErrCtl register=00000000
[ 0.000000] Memory: 19648K/32768K available (3544K kernel code, 144K rwdata, 492K rodata, 7972K init, 203K bss, 13120K reserved, 0K cma-reserved)
[ 0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] NR_IRQS: 51
[ 0.000000] CPU clock: 550.000 MHz
[ 0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 6950037990 ns
[ 0.000011] sched_clock: 32 bits at 275MHz, resolution 3ns, wraps every 7809031678ns
[ 0.008899] Calibrating delay loop... 366.18 BogoMIPS (lpj=1830912)
[ 0.075976] pid_max: default: 32768 minimum: 301
[ 0.081456] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.088993] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.102006] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[ 0.113239] futex hash table entries: 256 (order: -1, 3072 bytes)
[ 0.120271] pinctrl core: initialized pinctrl subsystem
[ 0.129130] NET: Registered protocol family 16
[ 0.159871] clocksource: Switched to clocksource MIPS
[ 0.166986] NET: Registered protocol family 2
[ 0.173070] TCP established hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.181077] TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.188304] TCP: Hash tables configured (established 1024 bind 1024)
[ 0.195734] UDP hash table entries: 256 (order: 0, 4096 bytes)
[ 0.202443] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[ 0.209932] NET: Registered protocol family 1
[ 0.441778] Crashlog allocated RAM at address 0x1f00000
[ 0.449761] workingset: timestamp_bits=30 max_order=13 bucket_order=0
[ 0.463652] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 0.470338] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORITY) (c) 2001-2006 Red Hat, Inc.
[ 0.573035] io scheduler noop registered
[ 0.577495] io scheduler deadline registered (default)
[ 0.586478] pinctrl-single 1804002c.pinmux: 576 pins at pa b804002c size 72
[ 0.595622] Serial: 8250/16550 driver, 16 ports, IRQ sharing enabled
[ 0.605887] console [ttyS0] disabled
[ 0.610067] 18020000.uart: ttyS0 at MMIO 0x18020000 (irq = 9, base_baud = 1562500) is a 16550A
[ 0.619896] console [ttyS0] enabled
[ 0.619896] console [ttyS0] enabled
[ 0.627446] bootconsole [early0] disabled
[ 0.627446] bootconsole [early0] disabled
[ 0.655906] m25p80 spi0.0: s25fl064k (8192 Kbytes)
[ 0.660968] 3 fixed-partitions partitions found on MTD device spi0.0
[ 0.667534] Creating 3 MTD partitions on "spi0.0":
[ 0.672514] 0x000000000000-0x000000020000 : "u-boot"
[ 0.678707] 0x000000020000-0x0000003f0000 : "firmware"
[ 0.685921] 2 tplink-fw partitions found on MTD device firmware
[ 0.692126] Creating 2 MTD partitions on "firmware":
[ 0.697268] 0x000000000000-0x00000036a170 : "kernel"
[ 0.703347] 0x000000370000-0x0000003d0000 : "rootfs"
[ 0.709470] mtd: device 3 (rootfs) set to be root filesystem
[ 0.715429] mtdsplit: no squashfs found in "rootfs"
[ 0.720527] 0x0000003f0000-0x000000400000 : "art"
[ 0.727132] libphy: Fixed MDIO Bus: probed
[ 1.071005] ag71xx 19000000.eth: Could not connect to PHY device. Deferring probe.
[ 1.750303] libphy: ag71xx_mdio: probed
[ 1.755849] libphy: ar8xxx-mdio: probed
[ 1.821951] switch0: Atheros AR8229 rev. 1 switch registered on mdio-bus.0
[ 1.908098] ag71xx 1a000000.eth: connected to PHY at fixed-0:00 [uid=00000000, driver=Generic PHY]
[ 1.918258] eth0: Atheros AG71xx at 0xba000000, irq 5, mode: gmii
[ 1.927890] NET: Registered protocol family 10
[ 1.939093] Segment Routing with IPv6
[ 1.943086] NET: Registered protocol family 17
[ 1.947742] bridge: filtering via arp/ip/ip6tables is no longer available by default. Update your scripts to load br_netfilter if you need this.
[ 1.961897] 8021q: 802.1Q VLAN Support v1.8
[ 2.302222] ag71xx 19000000.eth: connected to PHY at mdio-bus.0:1f:04 [uid=004dd042, driver=Generic PHY]
[ 2.313243] eth1: Atheros AG71xx at 0xb9000000, irq 4, mode: mii
[ 2.370657] Freeing unused kernel memory: 7972K
[ 2.375356] This architecture does not have kernel memory protection.
[ 2.403375] init: Console is alive
[ 2.407211] init: - watchdog -
[ 2.437672] kmodloader: loading kernel modules from /etc/modules-boot.d/*
[ 2.448667] kmodloader: done loading kernel modules from /etc/modules-boot.d/*
[ 2.466809] init: - preinit -
[ 2.509932] random: fast init done
[ 2.808648] random: jshn: uninitialized urandom read (4 bytes read)
[ 2.917601] random: jshn: uninitialized urandom read (4 bytes read)
[ 3.163179] random: jshn: uninitialized urandom read (4 bytes read)
[ 3.805753] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[ 3.811977] IPv6: ADDRCONF(NETDEV_UP): eth0.1: link is not ready
Press the [f] key and hit [enter] to enter failsafe mode
Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level
[ 4.821087] eth0: link up (1000Mbps/Full duplex)
[ 4.825913] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 4.833060] IPv6: ADDRCONF(NETDEV_CHANGE): eth0.1: link becomes ready
[ 7.014588] eth0: link down
[ 7.042239] procd: - early -
[ 7.045358] procd: - watchdog -
[ 7.636953] procd: - watchdog -
[ 7.640695] procd: - ubus -
[ 7.652470] urandom_read: 5 callbacks suppressed
[ 7.652481] random: ubusd: uninitialized urandom read (4 bytes read)
[ 7.694505] random: ubusd: uninitialized urandom read (4 bytes read)
[ 7.702822] procd: - init -
Please press Enter to activate this console.
[ 8.251779] kmodloader: loading kernel modules from /etc/modules.d/*
[ 8.275535] ip6_tables: (C) 2000-2006 Netfilter Core Team
[ 8.306112] Loading modules backported from Linux version v4.19.98-0-gd183c8e2647a
[ 8.314024] Backport generated by backports.git v4.19.98-1-0-g8204eb99
[ 8.342826] ip_tables: (C) 2000-2006 Netfilter Core Team
[ 8.369084] nf_conntrack version 0.5.0 (1024 buckets, 4096 max)
[ 8.509039] xt_time: kernel timezone is -0000
[ 8.643102] PPP generic driver version 2.4.2
[ 8.661009] NET: Registered protocol family 24
[ 8.746124] Data bus error, epc == 801f4180, ra == 8129febc
[ 8.751898] Oops[#1]:
[ 8.754255] CPU: 0 PID: 497 Comm: kmodloader Not tainted 4.14.167 #0
[ 8.760819] task: 81878000 task.stack: 811f8000
[ 8.765491] $ 0 : 00000000 00000001 deadc0de 00014000
[ 8.770901] $ 4 : b81143fc 000143fc 00014000 00000004
[ 8.776305] $ 8 : 00000001 7c7c3c7c 7c7c7c7c 7c7c7c7c
[ 8.781707] $12 : 7c7c3c7c 81236500 ffffff80 7c7c7c3c
[ 8.787120] $16 : 8115c080 00000018 00000000 00030000
[ 8.792522] $20 : 00010000 00031018 00000004 000003ff
[ 8.797925] $24 : 00000000 00000000
[ 8.803328] $28 : 811f8000 811f9a30 811f9a84 8129febc
[ 8.808740] Hi : 00000003
[ 8.811715] Lo : 000000ff
[ 8.814696] epc : 801f4180 0x801f4180
[ 8.818663] ra : 8129febc 0x8129febc [ath9k_hw@81280000+0x51660]
[ 8.825129] Status: 1000f403 KERNEL EXL IE
[ 8.829458] Cause : 1080001c (ExcCode 07)
[ 8.833598] PrId : 00019374 (MIPS 24Kc)
[ 8.837644] Modules linked in: ath9k(+) ath9k_common pppoe ppp_async ath9k_hw ath pppox ppp_generic nf_conntrack_ipv6 mac80211 iptable_nat ipt_REJECT ipt_MASQUERADE cfg80211 xt_time xt_tcpudp xt_state xt_nat xt_multiport xt_mark xt_mac xt_limit xt_conntrack xt_comment xt_TCPMSS xt_REDIRECT xt_LOG xt_FLOWOFFLOAD xt_CT slhc nf_reject_ipv4 nf_nat_redirect nf_nat_masquerade_ipv4 nf_conntrack_ipv4 nf_nat_ipv4 nf_nat nf_log_ipv4 nf_flow_table_hw nf_flow_table nf_defrag_ipv6 nf_defrag_ipv4 nf_conntrack_rtcache nf_conntrack iptable_mangle iptable_filter ip_tables crc_ccitt compat nf_log_ipv6 nf_log_common ip6table_mangle ip6table_filter ip6_tables ip6t_REJECT x_tables nf_reject_ipv6 gpio_button_hotplug
[ 8.901314] Process kmodloader (pid: 497, threadinfo=811f8000, task=81878000, tls=77fb3efc)
[ 8.909933] Stack : ffffffff 81236500 ffffff80 ffffffff 00002710 8115c080 000003ff 812a0000
[ 8.918580] 8111a800 8115c080 811f9b14 00000004 812ccda8 8115c4bc 00000001 8129ea64
[ 8.927226] 811f8000 811f9a98 00000220 00000220 00008000 ffffffff 811f9b14 812a0ab0
[ 8.935872] 8115a080 81283e88 00000001 80450000 812d9500 81201ff0 000186a0 8115c080
[ 8.944519] 8115c080 8115c0a8 00008000 00000001 811f9b14 00000004 812ccda8 99999999
[ 8.953165] ...
[ 8.955692] Call Trace:
[ 8.955740] [<812a0000>] 0x812a0000 [ath9k_hw@81280000+0x51660]
[ 8.964387] [<8129ea64>] 0x8129ea64 [ath9k_hw@81280000+0x51660]
[ 8.970516] [<812a0ab0>] 0x812a0ab0 [ath9k_hw@81280000+0x51660]
[ 8.976635] [<81283e88>] 0x81283e88 [ath9k_hw@81280000+0x51660]
[ 8.982755] [<81201ff0>] 0x81201ff0 [ath9k@81200000+0x16bb0]
[ 8.988619] [<812930f8>] 0x812930f8 [ath9k_hw@81280000+0x51660]
[ 8.994739] [<80093348>] 0x80093348
[ 8.998350] [<812864d0>] 0x812864d0 [ath9k_hw@81280000+0x51660]
[ 9.004467] [<80250bd8>] 0x80250bd8
[ 9.008081] [<80093348>] 0x80093348
[ 9.011691] [<812026a4>] 0x812026a4 [ath9k@81200000+0x16bb0]
[ 9.017543] [<800aefec>] 0x800aefec
[ 9.021168] [<8120e468>] 0x8120e468 [ath9k@81200000+0x16bb0]
[ 9.027023] [<80299160>] 0x80299160
[ 9.030649] [<8024f43c>] 0x8024f43c
[ 9.034250] [<8029367c>] 0x8029367c
[ 9.037852] [<8024db98>] 0x8024db98
[ 9.041454] [<8024fabc>] 0x8024fabc
[ 9.045058] [<8024dce4>] 0x8024dce4
[ 9.048656] [<8024bd38>] 0x8024bd38
[ 9.052263] [<8024dc60>] 0x8024dc60
[ 9.055870] [<8024bdf0>] 0x8024bdf0
[ 9.059471] [<803bf270>] 0x803bf270
[ 9.063074] [<8024bc3c>] 0x8024bc3c
[ 9.066680] [<8024d124>] 0x8024d124
[ 9.070291] [<8024e300>] 0x8024e300
[ 9.073905] [<81217000>] 0x81217000 [ath9k@81200000+0x16bb0]
[ 9.079748] [<8024e4a8>] 0x8024e4a8
[ 9.083366] [<81217018>] 0x81217018 [ath9k@81200000+0x16bb0]
[ 9.089214] [<80060a00>] 0x80060a00
[ 9.092822] [<800e6a40>] 0x800e6a40
[ 9.096423] [<800912d4>] 0x800912d4
[ 9.100025] [<8010fbe0>] 0x8010fbe0
[ 9.103642] [<800cbee4>] 0x800cbee4
[ 9.107247] [<80111044>] 0x80111044
[ 9.110854] [<800cb81c>] 0x800cb81c
[ 9.114462] [<800c9680>] 0x800c9680
[ 9.118071] [<80111a14>] 0x80111a14
[ 9.121673] [<8011c4e0>] 0x8011c4e0
[ 9.125275] [<800cbb3c>] 0x800cbb3c
[ 9.128878] [<800cbc28>] 0x800cbc28
[ 9.132487] [<8006ed8c>] 0x8006ed8c
[ 9.136093] [<803d0c74>] 0x803d0c74
[ 9.139698] [<800698a0>] 0x800698a0
[ 9.143307]
[ 9.144847] Code: 26310001 8c820000 0000000f <03e00008> 00000000 27bdffe8 afbf0014 0c0a76b2 00000000
[ 9.154936]
[ 9.156551] ---[ end trace eb9837c2a907321b ]---
[ 9.163433] Kernel panic - not syncing: Fatal exception
[ 9.169959] Rebooting in 1 seconds..


same crash and with public images:
https://downloads.openwrt.org/releases/19.07.0/targets/ath79/tiny/openwrt-19.07.0-ath79-tiny-tplink_tl-wr841-v9-initramfs-kernel.bin