dmesg.txt

root@lede:/# dmesg
[    0.000000] Linux version 4.4.42 (builder@3d0c773196e1) (gcc version 5.4.0 (LEDE GCC 5.4.0 r3011-5faad30) ) #0 Thu Jan 19 15:29:00 2017
[    0.000000] bootconsole [early0] enabled
[    0.000000] CPU0 revision is: 00019374 (MIPS 24Kc)
[    0.000000] SoC: Qualcomm Atheros QCA9533 ver 2 rev 0
[    0.000000] Determined physical RAM map:
[    0.000000]  memory: 02000000 @ 00000000 (usable)
[    0.000000] User-defined physical RAM map:
[    0.000000]  memory: 02000000 @ 00000000 (usable)
[    0.000000] Initrd not found or empty - disabling initrd
[    0.000000] No valid device tree found, continuing without
[    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] On node 0 totalpages: 8192
[    0.000000] free_area_init_node: node 0, pgdat 8046a3d0, node_mem_map 81000000
[    0.000000]   Normal zone: 64 pages used for memmap
[    0.000000]   Normal zone: 0 pages reserved
[    0.000000]   Normal zone: 8192 pages, LIFO batch:0
[    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] pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768
[    0.000000] pcpu-alloc: [0] 0
[    0.000000] Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 8128
[    0.000000] Kernel command line: console=ttyS0,115200 no-nand parts=1 boot_part_size=16777216 gpio=8586815 HZ=325000000 mem=32M kmac=6C:3B:6B:67:B0:1A board=H951L ver=3.22 hw_opt=00284000 boot=1 mlc=8 rootfstype=squashfs noinitrd
[    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: 27360K/32768K available (3288K kernel code, 167K rwdata, 812K rodata, 204K init, 198K bss, 5408K 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] Clocks: CPU:650.000MHz, DDR:400.000MHz, AHB:200.000MHz, Ref:25.000MHz
[    0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 5880801374 ns
[    0.000009] sched_clock: 32 bits at 325MHz, resolution 3ns, wraps every 6607641598ns
[    0.008856] Calibrating delay loop... 432.53 BogoMIPS (lpj=2162688)
[    0.071954] pid_max: default: 32768 minimum: 301
[    0.077326] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.084839] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.095920] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.107910] NET: Registered protocol family 16
[    0.114620] MIPS: machine is MikroTik RouterBOARD 941-2nD
[    0.353841] clocksource: Switched to clocksource MIPS
[    0.361063] NET: Registered protocol family 2
[    0.366856] TCP established hash table entries: 1024 (order: 0, 4096 bytes)
[    0.374846] TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
[    0.382073] TCP: Hash tables configured (established 1024 bind 1024)
[    0.389408] UDP hash table entries: 256 (order: 0, 4096 bytes)
[    0.396081] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[    0.403533] NET: Registered protocol family 1
[    0.408572] PCI: CLS 0 bytes, default 32
[    0.413506] futex hash table entries: 256 (order: -1, 3072 bytes)
[    0.420604] Crashlog allocated RAM at address 0x1f00000
[    0.440897] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[    0.447601] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORITY) (c) 2001-2006 Red Hat, Inc.
[    0.461849] io scheduler noop registered
[    0.466373] io scheduler deadline registered (default)
[    0.472480] Serial: 8250/16550 driver, 1 ports, IRQ sharing disabled
[    0.480179] console [ttyS0] disabled
[    0.504397] serial8250.0: ttyS0 at MMIO 0x18020000 (irq = 11, base_baud = 1562500) is a 16550A
[    0.514209] console [ttyS0] enabled
[    0.521756] bootconsole [early0] disabled
[    0.533266] m25p80 spi0.0: found w25q128, expected m25p80
[    0.538940] m25p80 spi0.0: w25q128 (16384 Kbytes)
[    0.543812] Creating 7 MTD partitions on "spi0.0":
[    0.548779] 0x000000000000-0x00000000e000 : "routerboot"
[    0.556530] 0x00000000e000-0x00000000f000 : "hard_config"
[    0.563931] 0x00000000f000-0x000000010000 : "bios"
[    0.570629] 0x000000010000-0x00000001f000 : "routerboot2"
[    0.578016] 0x00000001f000-0x000000020000 : "soft_config"
[    0.585412] 0x000000020000-0x000000a00000 : "rootfs"
[    0.592252] mtd: device 5 (rootfs) set to be root filesystem
[    0.598234] 1 squashfs-split partitions found on MTD device rootfs
[    0.604637] 0x0000001f8000-0x000000a00000 : "rootfs_data"
[    0.611948] 0x000000a00000-0x000001000000 : "kernel"
[    0.642977] libphy: ag71xx_mdio: probed
[    1.236177] ag71xx-mdio.1: Found an AR934X built-in switch
[    1.279750] eth0: Atheros AG71xx at 0xba000000, irq 5, mode:GMII
[    1.287973] NET: Registered protocol family 10
[    1.296540] NET: Registered protocol family 17
[    1.301218] bridge: automatic filtering via arp/ip/ip6tables has been deprecated. Update your scripts to load br_netfilter if you need this.
[    1.314450] 8021q: 802.1Q VLAN Support v1.8
[    1.329113] VFS: Mounted root (squashfs filesystem) readonly on device 31:5.
[    1.337864] Freeing unused kernel memory: 204K (8048d000 - 804c0000)
[    2.351030] init: Console is alive
[    2.354908] init: - watchdog -
[    3.262394] init: - preinit -
[    3.822617] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[    3.849921] random: procd: uninitialized urandom read (4 bytes read, 6 bits of entropy available)
[    5.916051] eth0: link up (1000Mbps/Full duplex)
[    5.930271] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[    7.057775] mount_root: no usable overlay filesystem found, using tmpfs overlay
[    7.069568] urandom-seed: Seed file not found (/etc/urandom.seed)
[    7.246879] eth0: link down
[    7.261341] procd: - early -
[    7.265205] procd: - watchdog -
[    7.881955] procd: - ubus -
[    7.935816] random: ubusd: uninitialized urandom read (4 bytes read, 13 bits of entropy available)
[    7.945658] random: ubusd: uninitialized urandom read (4 bytes read, 13 bits of entropy available)
[    7.955110] random: ubusd: uninitialized urandom read (4 bytes read, 13 bits of entropy available)
[    7.964877] random: ubusd: uninitialized urandom read (4 bytes read, 13 bits of entropy available)
[    7.974298] random: ubusd: uninitialized urandom read (4 bytes read, 13 bits of entropy available)
[    7.983784] random: ubusd: uninitialized urandom read (4 bytes read, 13 bits of entropy available)
[    7.993324] random: ubusd: uninitialized urandom read (4 bytes read, 13 bits of entropy available)
[    8.003120] procd: - init -
[    8.289667] ip6_tables: (C) 2000-2006 Netfilter Core Team
[    8.307464] Loading modules backported from Linux version wt-2016-10-03-1-g6fcb1a6
[    8.315374] Backport generated by backports.git backports-20160324-9-g0e38f5c
[    8.326238] ip_tables: (C) 2000-2006 Netfilter Core Team
[    8.340677] nf_conntrack version 0.5.0 (430 buckets, 1720 max)
[    8.383951] xt_time: kernel timezone is -0000
[    8.454882] PPP generic driver version 2.4.2
[    8.462045] NET: Registered protocol family 24
[    8.515302] ath: EEPROM regdomain: 0x0
[    8.515327] ath: EEPROM indicates default country code should be used
[    8.515336] ath: doing EEPROM country->regdmn map search
[    8.515357] ath: country maps to regdmn code: 0x3a
[    8.515369] ath: Country alpha2 being used: US
[    8.515377] ath: Regpair used: 0x3a
[    8.526993] ieee80211 phy0: Selected rate control algorithm 'minstrel_ht'
[    8.533261] ieee80211 phy0: Atheros AR9531 Rev:2 mem=0xb8100000, irq=47
[    9.867542] random: jshn: uninitialized urandom read (4 bytes read, 16 bits of entropy available)
[    9.940909] random: jshn: uninitialized urandom read (4 bytes read, 16 bits of entropy available)
[   14.713050] jffs2: Node at 0x00008044 with length 0x00001044 would run over the end of the erase block
[   14.722767] jffs2: Perhaps the file system was created with the wrong erase size?
[   14.753941] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0000804c: 0xee2d instead
[   14.763748] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00008064: 0x5884 instead
[   14.844140] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00008068: 0x5884 instead
[   14.853989] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0000806c: 0x5884 instead
[   14.863783] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00008080: 0xd0c8 instead
[   14.893921] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00008084: 0x98ff instead
[   14.903732] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00008088: 0x1f8b instead
[   14.933851] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00008090: 0x0203 instead
[   14.943653] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00008094: 0x0b94 instead
[   14.993885] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00008098: 0x7576 instead
[   15.003690] jffs2: Further such events for this erase block will not be printed
[   15.046592] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00009000: 0xea02 instead
[   15.083853] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00009004: 0x2770 instead
[   15.093664] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00009008: 0x38a2 instead
[   15.143876] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0000900c: 0xb762 instead
[   15.153688] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00009010: 0x2501 instead
[   15.193904] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00009014: 0x7d43 instead
[   15.203712] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00009018: 0xfd3d instead
[   15.263905] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0000901c: 0xb3b4 instead
[   15.273718] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00009020: 0x9a88 instead
[   15.323920] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00009024: 0x4f8c instead
[   15.333723] jffs2: Further such events for this erase block will not be printed
[   15.378502] jffs2_scan_eraseblock(): End of filesystem marker found at 0x18000
[   15.414606] jffs2_build_filesystem(): unlocking the mtd device... done.
[   15.421467] jffs2_build_filesystem(): erasing all blocks after the end marker...
[   19.165340] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[   19.191734] device eth0.1 entered promiscuous mode
[   19.196780] device eth0 entered promiscuous mode
[   19.252969] IPv6: ADDRCONF(NETDEV_UP): br-lan: link is not ready
[   19.360726] IPv6: ADDRCONF(NETDEV_UP): eth0.2: link is not ready
[   20.766065] eth0: link up (1000Mbps/Full duplex)
[   20.770885] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[   20.814006] br-lan: port 1(eth0.1) entered forwarding state
[   20.819844] br-lan: port 1(eth0.1) entered forwarding state
[   20.825745] IPv6: ADDRCONF(NETDEV_CHANGE): eth0.2: link becomes ready
[   20.945202] IPv6: ADDRCONF(NETDEV_CHANGE): br-lan: link becomes ready
[   22.813859] br-lan: port 1(eth0.1) entered forwarding state
[   54.629022] random: nonblocking pool is initialized

root@lede:/# mount
/dev/root on /rom type squashfs (ro,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,noatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,noatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime)
tmpfs on /tmp/root type tmpfs (rw,noatime,mode=755)
overlayfs:/tmp/root on / type overlay (rw,noatime,lowerdir=/,upperdir=/tmp/root/upper,workdir=/tmp/root/work)
tmpfs on /dev type tmpfs (rw,nosuid,relatime,size=512k,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,mode=600)
debugfs on /sys/kernel/debug type debugfs (rw,noatime)

mount -t jffs2 /dev/mtdblock6 /mnt/ 

later i tried: mount -t jffs2 /dev/mtdblock6 /mnt/, it was successfull in a few seconds. After all i got:

[  199.329180] jffs2: notice: (806) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orphan) and 0 of xref (0 dead, 0 orphan) found.

After reboot it seems to work fine, however:

root@lede:~# time dd if=/dev/urandom bs=1M count=2 of=test.rnd
2+0 records in
2+0 records out
real	0m 20.40s

Flashing using sysupgrade from such kernel also takes much longer time compared to the non/4 one, mostly hanged in [e] state.

In a first boot without 4k block option there are many 

[   19.586595] jffs2: CLEANMARKER node found at 0x004d2000, not first node in block (0x004d0000)
[   19.597764] jffs2: CLEANMARKER node found at 0x004d3000, not first node in block (0x004d0000)
[   19.608918] jffs2: CLEANMARKER node found at 0x004d4000, not first node in block (0x004d0000)
[   19.620099] jffs2: CLEANMARKER node found at 0x004d5000, not first node in block (0x004d0000)
[   19.631255] jffs2: CLEANMARKER node found at 0x004d6000, not first node in block (0x004d0000)
[   19.642447] jffs2: CLEANMARKER node found at 0x004d7000, not first node in block (0x004d0000)
[   19.653617] jffs2: CLEANMARKER node found at 0x004d8000, not first node in block (0x004d0000)
[   19.664817] jffs2: Empty flash at 0x004d800c ends at 0x004d9000

messages, but jffs2 related actions ends in 19s
[   19.822012] mount_root: switching to jffs2 overlay

Also dd works much faster:
root@lede:~#  time dd if=/dev/urandom bs=1M count=2 of=test.rnd
2+0 records in
2+0 records out
real	0m 13.19s
user	0m 0.00s
sys	0m 8.81s