How to create filesystem for linux4 with nios2

After deselecting Nios II DIV and configuring some more options, I get the login prompt and a shell via JTAG UART.

Welcome to Nios II
nios2 login: root
^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@
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login: root login on 'ttyJ0'
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Welcome to Nios IILinux version 4.9.0-00104-g84d4f8a-dirty (developer@1604) (gcc version 6.2.0 (Sourcery CodeBench Lite 2016.11-32) )# 64 Mon Apr 10 22:33:34 CEST 2017
bootconsole  enabled
early_console initialized at 0xe8001440
Warning: icache size configuration mismatch (0x8000 vs 0x1000) of CONFIG_NIOS2_ICACHE_SIZE vs device tree icache-size
Warning: dcache size configuration mismatch (0x8000 vs 0x800) of CONFIG_NIOS2_DCACHE_SIZE vs device tree dcache-size
On node 0 totalpages: 32768
��free_area_init_node: node 0, pgdat c042824c, node_mem_map c043fb80
  Normal zone: 256 pages used for memmap
  Normal zone: 0 pages reserved
  Normal zone: 32768 pages, LIFO batch:7
pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768
pcpu-alloc:  0 
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 32512
Kernel command line: 
PID hash table entries: 512 (order: -1, 2048 bytes)
Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
Sorting __ex_table...
��Memory: 125564K/131072K available (1878K kernel code, 57K rwdata, 440K rodata, 1876K init, 79K bss, 5508K reserved, 0K cma-reserved)
NR_IRQS:64 nr_irqs:64 0
clocksource: nios2-clksrc: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 38225208935 ns
Calibrating delay loop (skipped), value calculated using timer frequency.. 100.00 BogoMIPS (lpj=50000)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
devtmpfs: initialized
cpu cpu0: Error -2 creating of_node link
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275000 ns
random: fast init done
clocksource: Switched to clocksource nios2-clksrc
futex hash table entries: 256 (order: -1, 3072 bytes)
workingset: timestamp_bits=30 max_order=15 bucket_order=0
jffs2: version 2.2. (NAND) © 2001-2006 Red Hat, Inc.
Block layer SCSI generic (bsg) driver version 0.4 loaded (major 254)
io scheduler noop registered
io scheduler deadline registered
io scheduler cfq registered (default)
8001400.serial: ttyAL0 at MMIO 0x8001400 (irq = 3, base_baud = 3125000) is a Altera UART
8001440.serial: ttyJ0 at MMIO 0x8001440 (irq = 2, base_baud = 0) is a Altera JTAG UART
console  enabled
console  enabled
bootconsole  disabled
bootconsole  disabled
loop: module loaded
mousedev: PS/2 mouse device common for all mice
Freeing unused kernel memory: 1876K (c01d7000 - c03ac000)
This architecture does not have kernel memory protection.
^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@random: crng init done
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Initializing random number generator... ���...�����������������������������������������������������������������^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@done.
^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^��...���������������@...@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@Starting network: ip: socket: Function not implemented
ip: socket: Function not implemented
FAIL
Welcome to Nios II
nios2 login: root
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login: root login on 'ttyJ0'
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