cubieboard2-kernel-shutdown-problem

<0>Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,2)
[    4.462712] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,2)
[<c0015034>] (unwind_backtrace+0x0/0x138) from [<c05d9604>] (panic+0x8c/0x1d0)
[    4.478118] [<c0015034>] (unwind_backtrace+0x0/0x138) from [<c05d9604>] (panic+0x8c/0x1d0)
[<c05d9604>] (panic+0x8c/0x1d0) from [<c086fd70>] (mount_block_root+0x174/0x228)
[    4.493502] [<c05d9604>] (panic+0x8c/0x1d0) from [<c086fd70>] (mount_block_root+0x174/0x228)
[<c086fd70>] (mount_block_root+0x174/0x228) from [<c0870004>] (mount_root+0xf4/0x114)
[    4.509486] [<c086fd70>] (mount_block_root+0x174/0x228) from [<c0870004>] (mount_root+0xf4/0x114)
[<c0870004>] (mount_root+0xf4/0x114) from [<c0870188>] (prepare_namespace+0x164/0x1c8)
[    4.525990] [<c0870004>] (mount_root+0xf4/0x114) from [<c0870188>] (prepare_namespace+0x164/0x1c8)
[<c0870188>] (prepare_namespace+0x164/0x1c8) from [<c086fa24>] (kernel_init+0x1d4/0x218)
[    4.542754] [<c0870188>] (prepare_namespace+0x164/0x1c8) from [<c086fa24>] (kernel_init+0x1d4/0x218)
[<c086fa24>] (kernel_init+0x1d4/0x218) from [<c000f768>] (kernel_thread_exit+0x0/0x8)
[    4.559434] [<c086fa24>] (kernel_init+0x1d4/0x218) from [<c000f768>] (kernel_thread_exit+0x0/0x8)
<2>CPU1: stopping
[    4.569960] CPU1: stopping
[<c0015034>] (unwind_backtrace+0x0/0x138) from [<c0013b50>] (handle_IPI+0x194/0x1c8)
[    4.580142] [<c0015034>] (unwind_backtrace+0x0/0x138) from [<c0013b50>] (handle_IPI+0x194/0x1c8)
[<c0013b50>] (handle_IPI+0x194/0x1c8) from [<c00084fc>] (gic_handle_irq+0x50/0x58)
[    4.596214] [<c0013b50>] (handle_IPI+0x194/0x1c8) from [<c00084fc>] (gic_handle_irq+0x50/0x58)
[<c00084fc>] (gic_handle_irq+0x50/0x58) from [<c000e840>] (__irq_svc+0x40/0x70)
[    4.611852] [<c00084fc>] (gic_handle_irq+0x50/0x58) from [<c000e840>] (__irq_svc+0x40/0x70)
Exception stack(0xef065f88 to 0xef065fd0)
[    4.623930] Exception stack(0xef065f88 to 0xef065fd0)
5f80:                   ffffffed 00000001 0ff6d000 00000000 ef064000 ef064000
[    4.635835] 5f80:                   ffffffed 00000001 0ff6d000 00000000 ef064000 ef064000
5fa0: c0914188 c05e69d4 ef064000 410fc074 c08bcb50 00000000 ffff8c93 ef065fd0
[    4.650862] 5fa0: c0914188 c05e69d4 ef064000 410fc074 c08bcb50 00000000 ffff8c93 ef065fd0
5fc0: c000f7cc c000f7d0 60000013 ffffffff
[    4.662766] 5fc0: c000f7cc c000f7d0 60000013 ffffffff
[<c000e840>] (__irq_svc+0x40/0x70) from [<c000f7d0>] (default_idle+0x28/0x30)
[    4.674676] [<c000e840>] (__irq_svc+0x40/0x70) from [<c000f7d0>] (default_idle+0x28/0x30)
[<c000f7d0>] (default_idle+0x28/0x30) from [<c000fb04>] (cpu_idle+0xd0/0x114)
[    4.689707] [<c000f7d0>] (default_idle+0x28/0x30) from [<c000fb04>] (cpu_idle+0xd0/0x114)
[<c000fb04>] (cpu_idle+0xd0/0x114) from [<405d5e94>] (0x405d5e94)
[    4.703697] [<c000fb04>] (cpu_idle+0xd0/0x114) from [<405d5e94>] (0x405d5e94)
<6>[hotplug]: cpu(0) try to kill cpu(1)
[    4.714392] [hotplug]: cpu(0) try to kill cpu(1)
<3>[hotplug]: try to kill cpu:1 failed!
[    5.720225] [hotplug]: try to kill cpu:1 failed!