Hi,
I tried to compile and install the latest git master 559b3384666bbc6e4e9e6d86cf54bd88d30b341f for Mikrotik RB750gr3. It boots, but ethernet does not work at all:
OpenWrt kernel loader for MIPS based SoC
Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
Decompressing kernel... done!
Starting kernel at 80001000...
[ 0.000000] Linux version 5.4.42 (user@build) (gcc version 8.4.0 (OpenWrt GCC 8.4.0 r0-559b338)) #0 SMP Fri May 29 08:34:58 2020
[ 0.000000] SoC Type: MediaTek MT7621 ver:1 eco:3
[ 0.000000] printk: bootconsole [early0] enabled
[ 0.000000] CPU0 revision is: 0001992f (MIPS 1004Kc)
[ 0.000000] MIPS: machine is MikroTik RouterBOARD 750Gr3
[ 0.000000] Initrd not found or empty - disabling initrd
[ 0.000000] VPE topology {2,2} total 4
[ 0.000000] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[ 0.000000] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[ 0.000000] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x0000000000000000-0x000000000fffffff]
[ 0.000000] HighMem empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000000000000-0x000000000fffffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x000000000fffffff]
[ 0.000000] percpu: Embedded 14 pages/cpu s26672 r8192 d22480 u57344
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 64960
[ 0.000000] Kernel command line: console=ttyS0,115200 rootfstype=squashfs,jffs2
[ 0.000000] Dentry cache hash table entries: 32768 (order: 5, 131072 bytes, linear)
[ 0.000000] Inode-cache hash table entries: 16384 (order: 4, 65536 bytes, linear)
[ 0.000000] Writing ErrCtl register=00024570
[ 0.000000] Readback ErrCtl register=00024570
[ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[ 0.000000] Memory: 250864K/262144K available (5562K kernel code, 198K rwdata, 1216K rodata, 1268K init, 230K bss, 11280K reserved, 0K cma-reserved, 0K highmem)
[ 0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
[ 0.000000] rcu: Hierarchical RCU implementation.
[ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
[ 0.000000] NR_IRQS: 256
[ 0.000000] random: get_random_bytes called from start_kernel+0x340/0x550 with crng_init=0
[ 0.000000] CPU Clock: 880MHz
[ 0.000000] clocksource: GIC: mask: 0xffffffffffffffff max_cycles: 0xcaf478abb4, max_idle_ns: 440795247997 ns
[ 0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 4343773742 ns
[ 0.000009] sched_clock: 32 bits at 440MHz, resolution 2ns, wraps every 4880645118ns
[ 0.007790] Calibrating delay loop... 583.68 BogoMIPS (lpj=1167360)
[ 0.042002] pid_max: default: 32768 minimum: 301
[ 0.046765] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.053990] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.064434] rcu: Hierarchical SRCU implementation.
[ 0.069876] smp: Bringing up secondary CPUs ...
[ 3.490508] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[ 3.490519] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[ 3.490531] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[ 3.490633] CPU1 revision is: 0001992f (MIPS 1004Kc)
[ 0.102654] Synchronize counters for CPU 1: done.
[ 8.646694] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[ 8.646703] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[ 8.646712] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[ 8.646766] CPU2 revision is: 0001992f (MIPS 1004Kc)
[ 0.167382] Synchronize counters for CPU 2: done.
[ 4.209019] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[ 4.209028] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[ 4.209036] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[ 4.209094] CPU3 revision is: 0001992f (MIPS 1004Kc)
[ 0.225241] Synchronize counters for CPU 3: done.
[ 0.255112] smp: Brought up 1 node, 4 CPUs
[ 0.263447] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
[ 0.273144] futex hash table entries: 1024 (order: 3, 32768 bytes, linear)
[ 0.280248] pinctrl core: initialized pinctrl subsystem
[ 0.286999] NET: Registered protocol family 16
[ 0.319385] random: fast init done
[ 0.325503] clocksource: Switched to clocksource GIC
[ 0.332567] NET: Registered protocol family 2
[ 0.337641] tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 6144 bytes, linear)
[ 0.345934] TCP established hash table entries: 2048 (order: 1, 8192 bytes, linear)
[ 0.353557] TCP bind hash table entries: 2048 (order: 2, 16384 bytes, linear)
[ 0.360640] TCP: Hash tables configured (established 2048 bind 2048)
[ 0.367062] UDP hash table entries: 256 (order: 1, 8192 bytes, linear)
[ 0.373563] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes, linear)
[ 0.380709] NET: Registered protocol family 1
[ 0.385024] PCI: CLS 0 bytes, default 32
[ 0.477465] 4 CPUs re-calibrate udelay(lpj = 1167360)
[ 0.483903] workingset: timestamp_bits=14 max_order=16 bucket_order=2
[ 0.501938] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 0.507715] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORITY) (c) 2001-2006 Red Hat, Inc.
[ 0.520181] mt7621_gpio 1e000600.gpio: registering 32 gpios
[ 0.526040] mt7621_gpio 1e000600.gpio: registering 32 gpios
[ 0.531937] mt7621_gpio 1e000600.gpio: registering 32 gpios
[ 0.538376] Serial: 8250/16550 driver, 3 ports, IRQ sharing disabled
[ 0.546141] printk: console [ttyS0] disabled
[ 0.550436] 1e000c00.uartlite: ttyS0 at MMIO 0x1e000c00 (irq = 19, base_baud = 3125000) is a 16550A
[ 0.559419] printk: console [ttyS0] enabled
[ 0.559419] printk: console [ttyS0] enabled
[ 0.567677] printk: bootconsole [early0] disabled
[ 0.567677] printk: bootconsole [early0] disabled
[ 0.579821] spi-mt7621 1e000b00.spi: sys_freq: 220000000
[ 0.596654] spi-nor spi0.0: w25q128 (16384 Kbytes)
[ 0.601538] 2 fixed-partitions partitions found on MTD device spi0.0
[ 0.607877] Creating 2 MTD partitions on "spi0.0":
[ 0.612695] 0x000000000000-0x000000040000 : "RouterBoot"
[ 0.620238] 5 routerbootpart partitions found on MTD device RouterBoot
[ 0.626789] Creating 5 MTD partitions on "RouterBoot":
[ 0.631931] 0x000000000000-0x00000000f000 : "bootloader1"
[ 0.638427] 0x00000000f000-0x000000010000 : "hard_config"
[ 0.644934] 0x000000010000-0x00000001f000 : "bootloader2"
[ 0.651443] 0x000000020000-0x000000021000 : "soft_config"
[ 0.658004] 0x000000030000-0x000000031000 : "bios"
[ 0.663881] 0x000000040000-0x000001000000 : "firmware"
[ 0.670956] 2 minor-fw partitions found on MTD device firmware
[ 0.676831] Creating 2 MTD partitions on "firmware":
[ 0.681805] 0x000000000000-0x000000250000 : "kernel"
[ 0.687864] 0x000000250000-0x000000fc0000 : "rootfs"
[ 0.693905] mtd: device 8 (rootfs) set to be root filesystem
[ 0.699666] 1 squashfs-split partitions found on MTD device rootfs
[ 0.705846] 0x0000004f0000-0x000000fc0000 : "rootfs_data"
[ 0.713347] libphy: Fixed MDIO Bus: probed
[ 0.743885] libphy: mdio: probed
[ 0.747362] mt7530 mdio-bus:1f: MT7530 adapts as multi-chip module
[ 0.753715] mtk_soc_eth 1e100000.ethernet: generated random MAC address 4a:41:27:ff:f1:6e
[ 0.762675] mtk_soc_eth 1e100000.ethernet eth0: mediatek frame engine at 0xbe100000, irq 22
[ 0.775806] MikroTik RouterBOARD hardware configuration sysfs driver v0.04
[ 0.784735] MikroTik RouterBOARD software configuration sysfs driver v0.02
[ 0.792878] NET: Registered protocol family 10
[ 0.798936] Segment Routing with IPv6
[ 0.802749] NET: Registered protocol family 17
[ 0.807503] 8021q: 802.1Q VLAN Support v1.8
[ 0.813851] gpio-export gpio_export: 1 gpio(s) exported
[ 0.819253] mt7530 mdio-bus:1f: MT7530 adapts as multi-chip module
[ 1.709827] libphy: dsa slave smi: probed
[ 1.725536] mt7530 mdio-bus:1f wan (uninitialized): PHY [dsa-0.0:00] driver [Generic PHY]
[ 1.745543] mt7530 mdio-bus:1f lan2 (uninitialized): PHY [dsa-0.0:01] driver [Generic PHY]
[ 1.765551] mt7530 mdio-bus:1f lan3 (uninitialized): PHY [dsa-0.0:02] driver [Generic PHY]
[ 1.785547] mt7530 mdio-bus:1f lan4 (uninitialized): PHY [dsa-0.0:03] driver [Generic PHY]
[ 1.805560] mt7530 mdio-bus:1f lan5 (uninitialized): PHY [dsa-0.0:04] driver [Generic PHY]
[ 1.861492] mt7530 mdio-bus:1f: configuring for fixed/rgmii link mode
[ 2.477485] mt7530 mdio-bus:1f: Link is Up - 1Gbps/Full - flow control off
[ 2.553530] DSA: tree 0 setup
[ 2.557068] hctosys: unable to open rtc device (rtc0)
[ 2.568523] VFS: Mounted root (squashfs filesystem) readonly on device 31:8.
[ 2.579964] Freeing unused kernel memory: 1268K
[ 2.584519] This architecture does not have kernel memory protection.
[ 2.590944] Run /sbin/init as init process
[ 3.160742] init: Console is alive
[ 3.164411] init: - watchdog -
[ 3.506665] kmodloader: loading kernel modules from /etc/modules-boot.d/*
[ 3.621990] usbcore: registered new interface driver usbfs
[ 3.627636] usbcore: registered new interface driver hub
[ 3.633116] usbcore: registered new device driver usb
[ 3.648078] xhci-mtk 1e1c0000.xhci: 1e1c0000.xhci supply vbus not found, using dummy regulator
[ 3.656874] xhci-mtk 1e1c0000.xhci: 1e1c0000.xhci supply vusb33 not found, using dummy regulator
[ 3.665861] xhci-mtk 1e1c0000.xhci: xHCI Host Controller
[ 3.671205] xhci-mtk 1e1c0000.xhci: new USB bus registered, assigned bus number 1
[ 3.685649] xhci-mtk 1e1c0000.xhci: hcc params 0x01401198 hci version 0x96 quirks 0x0000000000210010
[ 3.694856] xhci-mtk 1e1c0000.xhci: irq 21, io mem 0x1e1c0000
[ 3.701910] hub 1-0:1.0: USB hub found
[ 3.705871] hub 1-0:1.0: 2 ports detected
[ 3.710578] xhci-mtk 1e1c0000.xhci: xHCI Host Controller
[ 3.715986] xhci-mtk 1e1c0000.xhci: new USB bus registered, assigned bus number 2
[ 3.723484] xhci-mtk 1e1c0000.xhci: Host supports USB 3.0 SuperSpeed
[ 3.730017] usb usb2: We don't know the algorithms for LPM for this host, disabling LPM.
[ 3.738989] hub 2-0:1.0: USB hub found
[ 3.742885] hub 2-0:1.0: 1 port detected
[ 3.751949] kmodloader: done loading kernel modules from /etc/modules-boot.d/*
[ 3.765805] init: - preinit -
[ 4.563851] mtk_soc_eth 1e100000.ethernet eth0: configuring for fixed/rgmii link mode
[ 4.572167] mtk_soc_eth 1e100000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx
[ 4.580629] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 4.789418] random: jshn: uninitialized urandom read (4 bytes read)
[ 4.898059] random: jshn: uninitialized urandom read (4 bytes read)
[ 4.960279] random: jshn: uninitialized urandom read (4 bytes read)
[ 5.197498] mt7530 mdio-bus:1f lan2: configuring for phy/gmii link mode
[ 5.229658] 8021q: adding VLAN 0 to HW filter on device lan2
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
[ 9.521303] jffs2: notice: (598) jffs2_build_xattr_subsystem: complete building xattr subsystem, 18 of xdatum (14 unchecked, 4 orphan) and 22 of xref (2 dead, 2 orphan) found.
[ 9.539096] mount_root: switching to jffs2 overlay
[ 9.562177] overlayfs: upper fs does not support tmpfile.
[ 9.574021] urandom-seed: Seeding with /etc/urandom.seed
[ 9.750337] procd: - early -
[ 9.753312] procd: - watchdog -
[ 10.341669] procd: - watchdog -
[ 10.345119] procd: - ubus -
[ 10.394876] urandom_read: 5 callbacks suppressed
[ 10.394889] random: ubusd: uninitialized urandom read (4 bytes read)
[ 10.407955] random: ubusd: uninitialized urandom read (4 bytes read)
[ 10.415811] procd: - init -
Please press Enter to activate this console.
[ 10.854879] kmodloader: loading kernel modules from /etc/modules.d/*
[ 10.875090] input: beeper as /devices/platform/beeper/input/input0
[ 10.901824] xt_time: kernel timezone is -0000
[ 10.921105] PPP generic driver version 2.4.2
[ 10.926830] NET: Registered protocol family 24
[ 10.940857] kmodloader: done loading kernel modules from /etc/modules.d/*
[ 11.057701] urngd: v1.0.2 started.
[ 11.192695] random: crng init done
[ 15.724522] mtk_soc_eth 1e100000.ethernet eth0: Link is Down
[ 15.839623] mtk_soc_eth 1e100000.ethernet eth0: configuring for fixed/rgmii link mode
[ 15.848027] mtk_soc_eth 1e100000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx
[ 15.853904] device eth0 entered promiscuous mode
[ 15.861502] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 15.868990] br-lan: port 1(eth0.1) entered blocking state
[ 15.874474] br-lan: port 1(eth0.1) entered disabled state
[ 15.880627] device eth0.1 entered promiscuous mode
[ 15.888953] br-lan: port 1(eth0.1) entered blocking state
[ 15.894480] br-lan: port 1(eth0.1) entered forwarding state
[ 22.534318] export_store: invalid GPIO 17
BusyBox v1.31.1 () built-in shell (ash)
_______ ________ __
| |.-----.-----.-----.| | | |.----.| |_
| - || _ | -__| || | | || _|| _|
|_______|| __|_____|__|__||________||__| |____|
|__| W I R E L E S S F R E E D O M
-----------------------------------------------------
OpenWrt SNAPSHOT, r0-559b338
-----------------------------------------------------
=== WARNING! =====================================
There is no root password defined on this device!
Use the "passwd" command to set up a new password
in order to prevent unauthorized SSH logins.
--------------------------------------------------
root@OpenWrt:/#
root@OpenWrt:/# ifconfig
br-lan Link encap:Ethernet HWaddr 6C:3B:6B:BD:3A:86
inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fdf9:51d2:bde1::1/60 Scope:Global
inet6 addr: fe80::6e3b:6bff:febd:3a86/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:2096 (2.0 KiB)
eth0 Link encap:Ethernet HWaddr 4A:41:27:FF:F1:6E
inet6 addr: fe80::4841:27ff:feff:f16e/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:48 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:7490 (7.3 KiB)
Interrupt:22
eth0.1 Link encap:Ethernet HWaddr 6C:3B:6B:BD:3A:86
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:2096 (2.0 KiB)
eth0.2 Link encap:Ethernet HWaddr 6C:3B:6B:BD:3A:87
inet6 addr: fe80::6e3b:6bff:febd:3a87/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:20 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:3362 (3.2 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:12 errors:0 dropped:0 overruns:0 frame:0
TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:816 (816.0 B) TX bytes:816 (816.0 B)
Ethernet does not work, the router does not respond to ping or ARP, neither inbound, not outbound
More interesting, when I plug ethernet into port 2 - the LED stays off. Other ports' leds are working correctly
But latest available release works fine: http://downloads.openwrt.org/releases/19.07.3/targets/ramips/mt7621/openwrt-19.07.3-ramips-mt7621-mikrotik_rb750gr3-squashfs-sysupgrade.bin