/***************************************************************************
 *          I.MX6 Kernel BUG at include/linux/netdevice.h:520!
 * 声明：
 *     导致这个问题的原因是对应网卡控制器上的phy已经被移除。
 *
 *                                        2015-12-19 晴 南山平山村 曾剑锋
 **************************************************************************/


一、内核错误：
　　......
    Warning: `zygote' uses 32-bit capabilities (legacy support in use)
    Request_suspend_state: wakeup (3->0) at 29001684005 (2000-01-01 00:00:31.557669337 UTC)
    Eth0: no PHY, assuming direct connection to switch
    PHY 0:00 not found
    Eth0: could not attach to PHY
    Acc_open
    Acc_release
    Ehci_fsl_bus_resume begins, Host 1
    Ehci_fsl_bus_resume ends, Host 1
    Ehci_fsl_bus_resume begins, DR
    Ehci_fsl_bus_suspend begins, Host 1
    Ehci_fsl_bus_suspend ends, Host 1
    Binder: release 2582:2594 transaction 4968 in, still active
    Binder: send failed reply for transaction 4968 to 2769:2769
    Binder: release 2582:2845 transaction 5078 in, still active
    Binder: send failed reply for transaction 5078 to 2717:2717
    Binder: send failed reply for transaction 5369 to 2816:2816
    Binder: send failed reply for transaction 5370 to 2804:2804
    Binder: send failed reply for transaction 5375 to 2854:2854
    Binder: 2816:2816 transaction failed 29189, size 84-0
    Binder: 2816:2816 transaction failed 29189, size 2788-4
    Alarm_release: clear alarm, pending 0
    Alarm_release: clear alarm, pending 0
    Request_suspend_state: wakeup (0->0) at 38110961674 (2000-01-01 00:00:40.666946005 UTC)
    Init: untracked pid 2271 exited
    Init: untracked pid 2276 exited
    Init: untracked pid 2854 exited
    Request_suspend_state: wakeup (0->0) at 42255187340 (2000-01-01 00:00:44.811172672 UTC)
    Kernel BUG at include/linux/netdevice.h:520!
    Unable to handle kernel NULL pointer dereference at virtual address 00000000
    Pgd = d0494000
    [00000000] *pgd=00000000
    Internal error: Oops: 805 [#1] PREEMPT SMP
    Modules linked in:
    CPU: 0    Not tainted  (3.0.35 #105)
    PC is at __bug+0x1c/0x28
    LR is at __bug+0x18/0x28
    Pc : [<c004efec>]    lr : [<c004efe8>]    psr: 60000013
    Sp : d01ebdf8  ip : c09527d0  fp : 00000001
    R10: d01ea000  r9 : d4149ae0  r8 : 00000000
    R7 : d45f2044  r6 : 00000000  r5 : c06f5f88  r4 : d45f2000
    R3 : 00000000  r2 : 00000000  r1 : d5ac5a00  r0 : 00000033
    Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
    Control: 10c53c7d  Table: 2049404a  DAC: 00000015
    
    PC: 0xc004ef6c:
    Ef6c  e1a04000 e24dd010 e590003c eb01c8db e3500000 0594003c 0a00000d e2841034
    Ef8c  e594002c e891000e e88d000f ea000003 e59d000c eb01c8d1 e3500000 0a000006
    Efac  e1a0000d eb000eac e3500000 aafffff7 e3a00000 e28dd010 e8bd8010 e59d000c
    Efcc  eafffffb e92d4008 e1a03000 e1a02001 e59f0010 e1a01003 eb1998f3 e3a03000
    Efec  e5833000 eafffffe c0830ff8 e3010014 e30012e1 e92d4008 e34c0083 ebfffff0
    F00c  e1a01000 e301002c e92d4008 e34c0083 eb1998e5 e3010014 e30012c5 e34c0083
    F02c  ebffffe7 e92d4008 e1a02000 e1a03001 e301004c e1a0100e e34c0083 eb1998da
    F04c  e3010014 e3001299 e34c0083 ebffffdc e92d4ff0 e24dd06c e1a06002 e1a08000
　　......

二、解决方案：
    1. 导致的原因是网卡的phy已经被移除造成的；
    2. 注释arch/arm/mach-mx6/board-mx6q_sabresd.c网卡注册:
        //imx6_init_fec(fec_data);