# NFS root wont boot on QEMU / KVM

## spacewalker

Hi folks,

driving me nuts since one entire day now: Using a recent Kernel on Host, I can's get a guest VM (KVM) to boot with root set to nfs. 

1. NFS-root support compiled in

2. NFS-Server working, share confirmed working

3. Switching guest kernel Versions makes no difference

4. Different kvm drivers (virtio, e1000) on guest make no difference

5. vhost-net enabled / disabled makes no difference

Any thoughts?

qemu startup command:

```
  

#DEBUG: (not daemonized)

start-stop-daemon --start --pidfile /var/run/nexus.virtual.pid --exec /usr/bin/qemu-kvm -- -vnc :2 -k de -smp 2 -cpu host -m 4096 -usb -usbdevice tablet -net nic,macaddr=52:54:00:12:34:71,model=virtio -net tap,script=no,downscript=no,ifname=tap0 -serial stdio -kernel /storage/_VM/nexus/sda1.boot/Kernel-3.13.2-V1 -append "root=/dev/nfs rootdelay=5 console=ttyAMA0 console=ttyS0 ip=192.168.0.22:192.168.0.21:192.168.0.21:255.255.255.0:nexus:eth0:off nfsroot=192.168.0.21:/storage/_VM/nexus/sda4.root.use nfsrootdebug" -name $NAME,process=VM-NEXUS -pidfile /var/run/nexus.virtual.pid

```

Here is the dmesg of the guest:

```

[    0.000000] Initializing cgroup subsys cpuset

[    0.000000] Initializing cgroup subsys cpu

[    0.000000] Initializing cgroup subsys cpuacct

[    0.000000] Linux version 3.13.2-gentoo (root@xxxx.xx) (gcc version 4.3.2 (Gentoo 4.3.2-r3 p1.6, pie-10.1.5) ) #3 SMP Thu Feb 13 17:41:32 CET 2014

[    0.000000] Command line: root=/dev/nfs rootdelay=5 console=ttyAMA0 console=ttyS0 ip=192.168.0.22:192.168.0.21:192.168.0.21:255.255.255.0:nexus:eth0:off nfsroot=192.168.0.21:/storage/_VM/nexus/sda4.root.use nfsrootdebug

[    0.000000] e820: BIOS-provided physical RAM map:

[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable

[    0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved

[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000dfffdfff] usable

[    0.000000] BIOS-e820: [mem 0x00000000dfffe000-0x00000000dfffffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000feffc000-0x00000000feffffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved

[    0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000011fffffff] usable

[    0.000000] NX (Execute Disable) protection: active

[    0.000000] SMBIOS 2.4 present.

[    0.000000] Hypervisor detected: KVM

[    0.000000] e820: last_pfn = 0x120000 max_arch_pfn = 0x400000000

[    0.000000] x86 PAT enabled: cpu 0, old 0x70406, new 0x7010600070106

[    0.000000] e820: last_pfn = 0xdfffe max_arch_pfn = 0x400000000

[    0.000000] found SMP MP-table at [mem 0x000f1840-0x000f184f] mapped at [ffff8800000f1840]

[    0.000000] Scanning 1 areas for low memory corruption

[    0.000000] Using GB pages for direct mapping

[    0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff]

[    0.000000] init_memory_mapping: [mem 0x11fe00000-0x11fffffff]

[    0.000000] init_memory_mapping: [mem 0x11c000000-0x11fdfffff]

[    0.000000] init_memory_mapping: [mem 0x100000000-0x11bffffff]

[    0.000000] init_memory_mapping: [mem 0x00100000-0xdfffdfff]

[    0.000000] ACPI: RSDP 00000000000f1690 000014 (v00 BOCHS )

[    0.000000] ACPI: RSDT 00000000dfffe3f0 000034 (v01 BOCHS  BXPCRSDT 00000001 BXPC 00000001)

[    0.000000] ACPI: FACP 00000000dfffff80 000074 (v01 BOCHS  BXPCFACP 00000001 BXPC 00000001)

[    0.000000] ACPI: DSDT 00000000dfffe430 001137 (v01   BXPC   BXDSDT 00000001 INTL 20100528)

[    0.000000] ACPI: FACS 00000000dfffff40 000040

[    0.000000] ACPI: SSDT 00000000dffff6a0 000899 (v01 BOCHS  BXPCSSDT 00000001 BXPC 00000001)

[    0.000000] ACPI: APIC 00000000dffff5b0 000080 (v01 BOCHS  BXPCAPIC 00000001 BXPC 00000001)

[    0.000000] ACPI: HPET 00000000dffff570 000038 (v01 BOCHS  BXPCHPET 00000001 BXPC 00000001)

[    0.000000] No NUMA configuration found

[    0.000000] Faking a node at [mem 0x0000000000000000-0x000000011fffffff]

[    0.000000] Initmem setup node 0 [mem 0x00000000-0x11fffffff]

[    0.000000]   NODE_DATA [mem 0x11fffa000-0x11fffdfff]

[    0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00

[    0.000000] kvm-clock: cpu 0, msr 1:1fff9001, boot clock

[    0.000000] Zone ranges:

[    0.000000]   DMA      [mem 0x00001000-0x00ffffff]

[    0.000000]   DMA32    [mem 0x01000000-0xffffffff]

[    0.000000]   Normal   [mem 0x100000000-0x11fffffff]

[    0.000000] Movable zone start for each node

[    0.000000] Early memory node ranges

[    0.000000]   node   0: [mem 0x00001000-0x0009efff]

[    0.000000]   node   0: [mem 0x00100000-0xdfffdfff]

[    0.000000]   node   0: [mem 0x100000000-0x11fffffff]

[    0.000000] ACPI: PM-Timer IO Port: 0xb008

[    0.000000] ACPI: LAPIC (acpi_id[0x00] lapic_id[0x00] enabled)

[    0.000000] ACPI: LAPIC (acpi_id[0x01] lapic_id[0x01] enabled)

[    0.000000] ACPI: LAPIC_NMI (acpi_id[0xff] dfl dfl lint[0x1])

[    0.000000] ACPI: IOAPIC (id[0x00] address[0xfec00000] gsi_base[0])

[    0.000000] IOAPIC[0]: apic_id 0, version 17, address 0xfec00000, GSI 0-23

[    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl)

[    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 5 global_irq 5 high level)

[    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)

[    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 10 global_irq 10 high level)

[    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 11 global_irq 11 high level)

[    0.000000] Using ACPI (MADT) for SMP configuration information

[    0.000000] ACPI: HPET id: 0x8086a201 base: 0xfed00000

[    0.000000] smpboot: Allowing 2 CPUs, 0 hotplug CPUs

[    0.000000] PM: Registered nosave memory: [mem 0x0009f000-0x0009ffff]

[    0.000000] PM: Registered nosave memory: [mem 0x000a0000-0x000effff]

[    0.000000] PM: Registered nosave memory: [mem 0x000f0000-0x000fffff]

[    0.000000] PM: Registered nosave memory: [mem 0xdfffe000-0xdfffffff]

[    0.000000] PM: Registered nosave memory: [mem 0xe0000000-0xfeffbfff]

[    0.000000] PM: Registered nosave memory: [mem 0xfeffc000-0xfeffffff]

[    0.000000] PM: Registered nosave memory: [mem 0xff000000-0xfffbffff]

[    0.000000] PM: Registered nosave memory: [mem 0xfffc0000-0xffffffff]

[    0.000000] e820: [mem 0xe0000000-0xfeffbfff] available for PCI devices

[    0.000000] Booting paravirtualized kernel on KVM

[    0.000000] setup_percpu: NR_CPUS:64 nr_cpumask_bits:64 nr_cpu_ids:2 nr_node_ids:1

[    0.000000] PERCPU: Embedded 28 pages/cpu @ffff88011fc00000 s85120 r8192 d21376 u1048576

[    0.000000] kvm-clock: cpu 0, msr 1:1fff9001, primary cpu clock

[    0.000000] KVM setup async PF for cpu 0

[    0.000000] kvm-stealtime: cpu 0, msr 11fc0df40

[    0.000000] Built 1 zonelists in Node order, mobility grouping on.  Total pages: 1032071

[    0.000000] Policy zone: Normal

[    0.000000] Kernel command line: root=/dev/nfs rootdelay=5 console=ttyAMA0 console=ttyS0 ip=192.168.0.22:192.168.0.21:192.168.0.21:255.255.255.0:nexus:eth0:off nfsroot=192.168.0.21:/storage/_VM/nexus/sda4.root.use nfsrootdebug

[    0.000000] PID hash table entries: 4096 (order: 3, 32768 bytes)

[    0.000000] Memory: 4042036K/4193904K available (11531K kernel code, 1035K rwdata, 3692K rodata, 1288K init, 1092K bss, 151868K reserved)

[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=1

[    0.000000] Hierarchical RCU implementation.

[    0.000000]  RCU restricting CPUs from NR_CPUS=64 to nr_cpu_ids=2.

[    0.000000] NR_IRQS:4352 nr_irqs:512 16

[    0.000000] Console: colour VGA+ 80x25

[    0.000000] console [ttyS0] enabled

[    0.000000] tsc: Detected 2400.030 MHz processor

[    0.008000] Calibrating delay loop (skipped) preset value.. 4800.06 BogoMIPS (lpj=9600120)

[    0.008000] pid_max: default: 32768 minimum: 301

[    0.008000] Security Framework initialized

[    0.008000] SELinux:  Initializing.

[    0.008444] Dentry cache hash table entries: 524288 (order: 10, 4194304 bytes)

[    0.010963] Inode-cache hash table entries: 262144 (order: 9, 2097152 bytes)

[    0.012319] Mount-cache hash table entries: 256

[    0.013140] Initializing cgroup subsys freezer

[    0.013851] Initializing cgroup subsys blkio

[    0.014487] Initializing cgroup subsys hugetlb

[    0.015206] mce: CPU supports 10 MCE banks

[    0.016006] Last level iTLB entries: 4KB 0, 2MB 0, 4MB 0

[    0.016006] Last level dTLB entries: 4KB 0, 2MB 0, 4MB 0

[    0.016006] tlb_flushall_shift: 6

[    0.018336] Freeing SMP alternatives memory: 44K (ffffffff82246000 - ffffffff82251000)

[    0.024026] ACPI: Core revision 20131115

[    0.025563] ACPI: All ACPI Tables successfully acquired

[    0.026701] Enabling x2apic

[    0.027181] Enabled x2apic

[    0.027790] Switched APIC routing to physical x2apic.

[    0.029154] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1

[    0.030201] smpboot: CPU0: Intel(R) Xeon(R) CPU           E5620  @ 2.40GHz (fam: 06, model: 2c, stepping: 02)

[    0.036000] Performance Events: 16-deep LBR, Westmere events, Intel PMU driver.

[    0.036000] perf_event_intel: CPUID marked event: 'bus cycles' unavailable

[    0.036000] ... version:                2

[    0.036000] ... bit width:              48

[    0.036003] ... generic registers:      4

[    0.036696] ... value mask:             0000ffffffffffff

[    0.037610] ... max period:             000000007fffffff

[    0.038488] ... fixed-purpose events:   3

[    0.039153] ... event mask:             000000070000000f

[    0.040063] KVM setup paravirtual spinlock

[    0.040964] x86: Booting SMP configuration:

[    0.041670] .... node  #0, CPUs:      #1[    0.008000] kvm-clock: cpu 1, msr 1:1fff9041, secondary cpu clock

[    0.056032] x86: Booted up 1 node, 2 CPUs

[    0.056023] KVM setup async PF for cpu 1

[    0.056023] kvm-stealtime: cpu 1, msr 11fd0df40

[    0.057916] smpboot: Total of 2 processors activated (9600.12 BogoMIPS)

[    0.060370] devtmpfs: initialized

[    0.060752] kworker/u4:0 (18) used greatest stack depth: 6672 bytes left

[    0.061319] RTC time: 19:35:04, date: 02/13/14

[    0.064046] NET: Registered protocol family 16

[    0.064846] kworker/u4:0 (29) used greatest stack depth: 6576 bytes left

[    0.064846] cpuidle: using governor ladder

[    0.064846] cpuidle: using governor menu

[    0.065275] ACPI: bus type PCI registered

[    0.068034] kworker/u4:0 (35) used greatest stack depth: 6144 bytes left

[    0.068034] dca service started, version 1.12.1

[    0.068170] PCI: Using configuration type 1 for base access

[    0.068253] kworker/u4:0 (41) used greatest stack depth: 5808 bytes left

[    0.092150] bio: create slab <bio-0> at 0

[    0.096040] ACPI: Added _OSI(Module Device)

[    0.096877] ACPI: Added _OSI(Processor Device)

[    0.097723] ACPI: Added _OSI(3.0 _SCP Extensions)

[    0.098608] ACPI: Added _OSI(Processor Aggregator Device)

[    0.103248] ACPI: Interpreter enabled

[    0.104009] ACPI Exception: AE_NOT_FOUND, While evaluating Sleep State [\_S1_] (20131115/hwxface-580)

[    0.105762] ACPI Exception: AE_NOT_FOUND, While evaluating Sleep State [\_S2_] (20131115/hwxface-580)

[    0.107104] ACPI: (supports S0 S3 S4 S5)

[    0.107667] ACPI: Using IOAPIC for interrupt routing

[    0.108031] PCI: Using host bridge windows from ACPI; if necessary, use "pci=nocrs" and report a bug

[    0.109745] ACPI: No dock devices found.

[    0.116270] ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-ff])

[    0.117044] acpi PNP0A03:00: _OSC: OS supports [ASPM ClockPM Segments MSI]

[    0.118033] acpi PNP0A03:00: _OSC failed (AE_NOT_FOUND); disabling ASPM

[    0.119597] acpi PNP0A03:00: fail to add MMCONFIG information, can't access extended PCI configuration space under this bridge.

[    0.124153] PCI host bridge to bus 0000:00

[    0.125025] pci_bus 0000:00: root bus resource [bus 00-ff]

[    0.125025] pci_bus 0000:00: root bus resource [io  0x0000-0x0cf7]

[    0.125463] pci_bus 0000:00: root bus resource [io  0x0d00-0xffff]

[    0.126884] pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000bffff]

[    0.128040] pci_bus 0000:00: root bus resource [mem 0xe0000000-0xfebfffff]

[    0.144352] pci 0000:00:01.3: quirk: [io  0xb000-0xb03f] claimed by PIIX4 ACPI

[    0.144352] pci 0000:00:01.3: quirk: [io  0xb100-0xb10f] claimed by PIIX4 SMB

[    0.172577] ACPI: PCI Interrupt Link [LNKA] (IRQs 5 *10 11)

[    0.172577] ACPI: PCI Interrupt Link [LNKB] (IRQs 5 *10 11)

[    0.173412] ACPI: PCI Interrupt Link [LNKC] (IRQs 5 10 *11)

[    0.174479] ACPI: PCI Interrupt Link [LNKD] (IRQs 5 10 *11)

[    0.175455] ACPI: PCI Interrupt Link [LNKS] (IRQs *9)

[    0.176341] ACPI: Enabled 16 GPEs in block 00 to 0F

[    0.176993] vgaarb: device added: PCI:0000:00:02.0,decodes=io+mem,owns=io+mem,locks=none

[    0.177229] vgaarb: loaded

[    0.177624] vgaarb: bridge control possible 0000:00:02.0

[    0.180061] SCSI subsystem initialized

[    0.180643] ACPI: bus type USB registered

[    0.184005] usbcore: registered new interface driver usbfs

[    0.184845] usbcore: registered new interface driver hub

[    0.184845] usbcore: registered new device driver usb

[    0.184845] pps_core: LinuxPPS API ver. 1 registered

[    0.184845] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>

[    0.188025] PTP clock support registered

[    0.188644] Advanced Linux Sound Architecture Driver Initialized.

[    0.188957] PCI: Using ACPI for IRQ routing

[    0.192079] NetLabel: Initializing

[    0.192609] NetLabel:  domain hash size = 128

[    0.193251] NetLabel:  protocols = UNLABELED CIPSOv4

[    0.193251] NetLabel:  unlabeled traffic allowed by default

[    0.193251] cfg80211: Calling CRDA to update world regulatory domain

[    0.196115] HPET: 3 timers in total, 0 timers will be used for per-cpu timer

[    0.197163] hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0

[    0.197163] hpet0: 3 comparators, 64-bit 100.000000 MHz counter

[    0.204081] Switched to clocksource kvm-clock

[    0.211693] FS-Cache: Loaded

[    0.220534] pnp: PnP ACPI init

[    0.221005] ACPI: bus type PNP registered

[    0.223071] pnp: PnP ACPI: found 8 devices

[    0.223675] ACPI: bus type PNP unregistered

[    0.229469] NET: Registered protocol family 2

[    0.230440] TCP established hash table entries: 32768 (order: 6, 262144 bytes)

[    0.231858] TCP bind hash table entries: 32768 (order: 7, 524288 bytes)

[    0.233214] TCP: Hash tables configured (established 32768 bind 32768)

[    0.234444] TCP: reno registered

[    0.235051] UDP hash table entries: 2048 (order: 4, 65536 bytes)

[    0.236237] UDP-Lite hash table entries: 2048 (order: 4, 65536 bytes)

[    0.237290] NET: Registered protocol family 1

[    0.238077] RPC: Registered named UNIX socket transport module.

[    0.238931] RPC: Registered udp transport module.

[    0.239599] RPC: Registered tcp transport module.

[    0.240285] RPC: Registered tcp NFSv4.1 backchannel transport module.

[    0.241204] pci 0000:00:00.0: Limiting direct PCI/PCI transfers

[    0.242059] pci 0000:00:01.0: PIIX3: Enabling Passive Release

[    0.242892] pci 0000:00:01.0: Activating ISA DMA hang workarounds

[    0.244090] ACPI: PCI Interrupt Link [LNKD] enabled at IRQ 11

[    0.245571] PCI-DMA: Using software bounce buffering for IO (SWIOTLB)

[    0.246502] software IO TLB [mem 0xdbffe000-0xdfffe000] (64MB) mapped at [ffff8800dbffe000-ffff8800dfffdfff]

[    0.247961] kvm: no hardware support

[    0.249838] microcode: CPU0 sig=0x206c2, pf=0x1, revision=0x1

[    0.251308] microcode: CPU1 sig=0x206c2, pf=0x1, revision=0x1

[    0.252292] microcode: Microcode Update Driver: v2.00 <tigran@aivazian.fsnet.co.uk>, Peter Oruba

[    0.253553] Scanning for low memory corruption every 60 seconds

[    0.255548] audit: initializing netlink socket (disabled)

[    0.256367] type=2000 audit(1392320104.696:1): initialized

[    0.287130] HugeTLB registered 2 MB page size, pre-allocated 0 pages

[    0.295702] VFS: Disk quotas dquot_6.5.2

[    0.296811] Dquot-cache hash table entries: 512 (order 0, 4096 bytes)

[    0.299513] FS-Cache: Netfs 'nfs' registered for caching

[    0.300830] NFS: Registering the id_resolver key type

[    0.301706] Key type id_resolver registered

[    0.302446] Key type id_legacy registered

[    0.303128] nfs4filelayout_init: NFSv4 File Layout Driver Registering...

[    0.304309] Installing knfsd (copyright (C) 1996 okir@monad.swb.de).

[    0.305927] Key type cifs.idmap registered

[    0.306794] msgmni has been set to 7894

[    0.308763] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 250)

[    0.309978] io scheduler noop registered

[    0.310606] io scheduler deadline registered (default)

[    0.311498] io scheduler cfq registered

[    0.312496] pci_hotplug: PCI Hot Plug PCI Core version: 0.5

[    0.313641] pciehp: PCI Express Hot Plug Controller Driver version: 0.4

[    0.314880] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled

[    0.337430] 00:05: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A

[    0.340274] Non-volatile memory driver v1.3

[    0.341191] Linux agpgart interface v0.103

[    0.342307] ipmi message handler version 39.2

[    0.343123] input: Power Button as /devices/LNXSYSTM:00/LNXPWRBN:00/input/input0

[    0.344226] ACPI: Power Button [PWRF]

[    0.345754] GHES: HEST is not enabled!

[    0.346415] ioatdma: Intel(R) QuickData Technology Driver 4.00

[    0.348145] ACPI: PCI Interrupt Link [LNKC] enabled at IRQ 10

[    0.350181] xenfs: not registering filesystem on non-xen platform

[    0.351492] [drm] Initialized drm 1.1.0 20060810

[    0.352448] drm/i810 does not support SMP

[    0.355669] loop: module loaded

[    0.356504] nbd: registered device at major 43

[    0.362061] blk-mq: CPU -> queue map

[    0.362735]   CPU 0 -> Queue 0

[    0.363251]   CPU 1 -> Queue 0

[    0.363996]  nullb0: unknown partition table

[    0.364962] blk-mq: CPU -> queue map

[    0.365627]   CPU 0 -> Queue 0

[    0.366144]   CPU 1 -> Queue 0

[    0.366930]  nullb1: unknown partition table

[    0.367859] null: module loaded

[    0.368792] Loading iSCSI transport class v2.0-870.

[    0.370959] iscsi: registered transport (tcp)

[    0.371727] 3ware 9000 Storage Controller device driver for Linux v2.26.02.014.

[    0.373109] LSI 3ware SAS/SATA-RAID Controller device driver for Linux v3.26.02.000.

[    0.374524] VMware PVSCSI driver - version 1.0.2.0-k

[    0.378036] scsi0 : ata_piix

[    0.378865] scsi1 : ata_piix

[    0.379609] ata1: PATA max MWDMA2 cmd 0x1f0 ctl 0x3f6 bmdma 0xc040 irq 14

[    0.380840] ata2: PATA max MWDMA2 cmd 0x170 ctl 0x376 bmdma 0xc048 irq 15

[    0.383258] bonding: Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)

[    0.387865] tun: Universal TUN/TAP device driver, 1.6

[    0.388835] tun: (C) 1999-2004 Max Krasnyansky <maxk@qualcomm.com>

[    0.391086] e100: Intel(R) PRO/100 Network Driver, 3.5.24-k2-NAPI

[    0.392159] e100: Copyright(c) 1999-2006 Intel Corporation

[    0.393270] e1000: Intel(R) PRO/1000 Network Driver - version 7.3.21-k8-NAPI

[    0.394547] e1000: Copyright (c) 1999-2006 Intel Corporation.

[    0.395703] e1000e: Intel(R) PRO/1000 Network Driver - 2.3.2-k

[    0.396843] e1000e: Copyright(c) 1999 - 2013 Intel Corporation.

[    0.398085] igb: Intel(R) Gigabit Ethernet Network Driver - version 5.0.5-k

[    0.399345] igb: Copyright (c) 2007-2013 Intel Corporation.

[    0.400571] igbvf: Intel(R) Gigabit Virtual Function Network Driver - version 2.0.2-k

[    0.401994] igbvf: Copyright (c) 2009 - 2012 Intel Corporation.

[    0.403215] ixgbe: Intel(R) 10 Gigabit PCI Express Network Driver - version 3.15.1-k

[    0.404661] ixgbe: Copyright (c) 1999-2013 Intel Corporation.

[    0.405664] ixgbevf: Intel(R) 10 Gigabit PCI Express Virtual Function Network Driver - version 2.11.3-k

[    0.407021] ixgbevf: Copyright (c) 2009 - 2012 Intel Corporation.

[    0.408088] i40e: Intel(R) Ethernet Connection XL710 Network Driver - version 0.3.11-k

[    0.409252] i40e: Copyright (c) 2013 Intel Corporation.

[    0.410188] ixgb: Intel(R) PRO/10GbE Network Driver - version 1.0.135-k2-NAPI

[    0.411244] ixgb: Copyright (c) 1999-2008 Intel Corporation.

[    0.412341] sky2: driver version 1.30

[    0.413844] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver

[    0.414830] ehci-pci: EHCI PCI platform driver

[    0.415572] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver

[    0.416567] ohci-pci: OHCI PCI platform driver

[    0.417440] uhci_hcd: USB Universal Host Controller Interface driver

[    0.419627] uhci_hcd 0000:00:01.2: UHCI Host Controller

[    0.420769] uhci_hcd 0000:00:01.2: new USB bus registered, assigned bus number 1

[    0.422009] uhci_hcd 0000:00:01.2: detected 2 ports

[    0.422902] uhci_hcd 0000:00:01.2: irq 11, io base 0x0000c020

[    0.423946] usb usb1: New USB device found, idVendor=1d6b, idProduct=0001

[    0.425149] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1

[    0.426376] usb usb1: Product: UHCI Host Controller

[    0.427236] usb usb1: Manufacturer: Linux 3.13.2-gentoo uhci_hcd

[    0.428321] usb usb1: SerialNumber: 0000:00:01.2

[    0.429461] hub 1-0:1.0: USB hub found

[    0.430015] hub 1-0:1.0: 2 ports detected

[    0.430939] usbcore: registered new interface driver usblp

[    0.431853] usbcore: registered new interface driver usb-storage

[    0.433029] i8042: PNP: PS/2 Controller [PNP0303:KBD,PNP0f13:MOU] at 0x60,0x64 irq 1,12

[    0.434943] serio: i8042 KBD port at 0x60,0x64 irq 1

[    0.435700] serio: i8042 AUX port at 0x60,0x64 irq 12

[    0.436710] mousedev: PS/2 mouse device common for all mice

[    0.438111] input: AT Translated Set 2 keyboard as /devices/platform/i8042/serio0/input/input1

[    0.439477] I2O subsystem v1.325

[    0.440025] i2o: max drivers = 8

[    0.442567] I2O Configuration OSM v1.323

[    0.443907] I2O Bus Adapter OSM v1.317

[    0.444662] I2O Block Device OSM v1.325

[    0.445669] I2O SCSI Peripheral OSM v1.316

[    0.446522] I2O ProcFS OSM v1.316

[    0.447272] rtc_cmos 00:00: RTC can wake from S4

[    0.448567] rtc_cmos 00:00: rtc core: registered rtc_cmos as rtc0

[    0.449653] rtc_cmos 00:00: alarms up to one day, 114 bytes nvram, hpet irqs

[    0.450861] i2c /dev entries driver

[    0.452100] device-mapper: ioctl: 4.27.0-ioctl (2013-10-30) initialised: dm-devel@redhat.com

[    0.453721] hidraw: raw HID events driver (C) Jiri Kosina

[    0.456628] usbcore: registered new interface driver usbhid

[    0.457606] usbhid: USB HID core driver

[    0.458803] intel_oaktrail: Platform not recognized (You could try the module's force-parameter)

[    0.461384] Netfilter messages via NETLINK v0.30.

[    0.462279] nf_conntrack version 0.5.0 (16384 buckets, 65536 max)

[    0.463493] ctnetlink v0.93: registering with nfnetlink.

[    0.464547] ip_tables: (C) 2000-2006 Netfilter Core Team

[    0.465567] TCP: cubic registered

[    0.466167] Initializing XFRM netlink socket

[    0.467433] NET: Registered protocol family 10

[    0.468529] ip6_tables: (C) 2000-2006 Netfilter Core Team

[    0.469502] sit: IPv6 over IPv4 tunneling driver

[    0.470746] NET: Registered protocol family 17

[    0.471559] 8021q: 802.1Q VLAN Support v1.8

[    0.472375] Key type dns_resolver registered

[    0.473105] openvswitch: Open vSwitch switching datapath

[    0.475083] registered taskstats version 1

[    0.476429]   Magic number: 2:995:596

[    0.477103] console [netcon0] enabled

[    0.477764] netconsole: network logging started

[    0.478917] 8021q: adding VLAN 0 to HW filter on device eth0

[    0.492154] IP-Config: Complete:

[    0.492977]      device=eth0, hwaddr=52:54:00:12:34:71, ipaddr=192.168.0.22, mask=255.255.255.0, gw=192.168.0.21

[    0.495625]      host=nexus, domain=, nis-domain=(none)

[    0.497046]      bootserver=192.168.0.21, rootserver=192.168.0.21, rootpath=

[    0.498832] ALSA device list:

[    0.499517]   No soundcards found.

[    0.500724] Waiting 5 sec before mounting root device...

[    0.537243] ata2.00: ATAPI: QEMU DVD-ROM, 1.6.1, max UDMA/100

[    0.539273] ata2.00: configured for MWDMA2

[    0.541114] scsi 1:0:0:0: CD-ROM            QEMU     QEMU DVD-ROM     1.6. PQ: 0 ANSI: 5

[    0.543781] sr0: scsi3-mmc drive: 4x/4x cd/rw xa/form2 tray

[    0.544850] cdrom: Uniform CD-ROM driver Revision: 3.20

[    0.547366] sr 1:0:0:0: Attached scsi generic sg0 type 5

[    0.740121] usb 1-1: new full-speed USB device number 2 using uhci_hcd

[    0.906166] usb 1-1: New USB device found, idVendor=0627, idProduct=0001

[    0.907870] usb 1-1: New USB device strings: Mfr=1, Product=3, SerialNumber=5

[    0.909712] usb 1-1: Product: QEMU USB Tablet

[    0.910771] usb 1-1: Manufacturer: QEMU

[    0.911674] usb 1-1: SerialNumber: 42

[    0.922237] input: QEMU QEMU USB Tablet as /devices/pci0000:00/0000:00:01.2/usb1/1-1/1-1:1.0/input/input4

[    0.925426] hid-generic 0003:0627:0001.0001: input,hidraw0: USB HID v0.01 Pointer [QEMU QEMU USB Tablet] on usb-0000:00:01.2-1/input0

[    1.041681] input: ImExPS/2 Generic Explorer Mouse as /devices/platform/i8042/serio1/input/input3

[    1.248155] tsc: Refined TSC clocksource calibration: 2399.994 MHz

[    5.504121] md: Waiting for all devices to be available before autodetect

[    5.505449] md: If you don't use raid, use raid=noautodetect

[    5.507325] md: Autodetecting RAID arrays.

[    5.508080] md: Scanned 0 and added 0 devices.

[    5.508927] md: autorun ...

[    5.509557] md: ... autorun DONE.

[  100.534698] VFS: Unable to mount root fs via NFS, trying floppy.

[  100.536140] VFS: Cannot open root device "nfs" or unknown-block(2,0): error -6

[  100.537437] Please append a correct "root=" boot option; here are the available partitions:

[  100.538999] fc00       262144000 nullb0  (driver?)

[  100.540338] fc01       262144000 nullb1  (driver?)

[  100.541538] 0b00         1048575 sr0  driver: sr

[  100.542691] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)

[  100.544281] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.13.2-gentoo #3

[  100.544281] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011

[  100.544281]  00000000fffffffa ffff88011aa53d28 ffffffff81b2e749 ffff88011aa53e28

[  100.544281]  ffffffff81b2e250 0000003000000010 ffff88011aa53e38 ffff88011aa53d58

[  100.544281]  ffffffff81e7c618 ffff88011aa53da8 ffff88011aa53e48 0000000000000000

[  100.544281] Call Trace:

[  100.544281]  [<ffffffff81b2e749>] dump_stack+0x6a/0x76

[  100.544281]  [<ffffffff81b2e250>] panic+0xf8/0x237

[  100.544281]  [<ffffffff811eb7e8>] ? SyS_mount+0x58/0xe0

[  100.544281]  [<ffffffff8211a871>] mount_block_root+0x21f/0x24b

[  100.544281]  [<ffffffff8211a8f5>] mount_root+0x58/0x109

[  100.544281]  [<ffffffff8211aaa1>] prepare_namespace+0xfb/0x16a

[  100.544281]  [<ffffffff82119bc4>] kernel_init_freeable+0x250/0x272

[  100.544281]  [<ffffffff82119be6>] ? kernel_init_freeable+0x272/0x272

[  100.544281]  [<ffffffff81b29e70>] ? rest_init+0x80/0x80

[  100.544281]  [<ffffffff81b29e79>] kernel_init+0x9/0x130

[  100.544281]  [<ffffffff81b3ca4c>] ret_from_fork+0x7c/0xb0

[  100.544281]  [<ffffffff81b29e70>] ? rest_init+0x80/0x80

```

----------

## spacewalker

Solved.

Short answer: Wrong NFS version.

Tricky: By default, Linux seems to mount an NFS root using NFS-V2, even with recent Kernels. I could not find any Documentation about this. Also, in recent editions of NFS-Utils, NFS V2 is disabled by default. Result: Protocol is not supported. No such error messages are displayed anywhere - not on Host NFS logs and not in DMESG of guest Kernel. 

Solution here: Appended ",vers=3" to nfsroot kernel parameter in KVM startup script:

```
-kernel /storage/_VM/gentoo.blank/sda1.boot/Kernel-3.13.1-Virtual-V1 -append "root=/dev/nfs rw rootdelay=1 ip=192.168.0.55:192.168.0.21:192.168.0.2:255.255.255.0:gentoovm:eth0:off nfsroot=192.168.0.21:/storage/_VM/gentoo.blank/sda3.root,vers=3 nfsrootdebug"
```

works.

Background: In an older installation of nfs-utils, the same VM would come up. After emerge world, nfs-utils got upgraded too and the VM broke. Since all other clients I have natively support all kinds of NFS versions, there seemed to be no error on NFS. And actually, there is none. The way I figured it out was to manually mount a NFS share from the client with the same options my guest kernel used while booting (these are displayed). So, forcing a NFS V2 mount on a client would fail.

----------

