在我的嵌入式系统上，有一个实时时钟 (RTC) 连接到 uart 2。
21e8000.serial: ttymxc1 at MMIO 0x21e8000 (irq = 59, base_baud = 5000000) is a IMX
我编写了一个 rtc 内核驱动程序，它使用 filp_open("/dev/ttymxc1", O_RDWR | O_NOCTTY | O_SYNC, 0) 与 RTC 通信。在我启动并登录后，一切正常。hwclock 做它应该做的事情。问题是在引导过程中 filp_open 返回 -2 /* ENOENT - 没有这样的文件或目录 */。
silhouettestar2_rtc rtc.24: RTC-SilhouetteStar2: file open error = -2
我的 rtc_read_time 函数在启动过程中被调用了两次，两次都返回了相同的错误。Dmesg 显示 uart 驱动程序在 RTC 驱动程序之前加载。我怀疑 ttymxc1 尚未启用。像控制台一样加载驱动程序时可以启用 ttymxc1 吗？内核模块中是否可以使用另一个接口直接与 ttymxc1 通信？
$> dmesg
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 3.14.79+g5dcba44 (schustercp@Ubuntu-Dev2) (gcc version 4.9.2 (GCC) ) #1 SMP Tue May 1 15:46:06 NZST 2018
[ 0.000000] CPU: ARMv7 Processor [412fc09a] revision 10 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] Machine model: ARANZ SilhouetteStar with i.MX6 Solo/DualLite
[ 0.000000] cma: dma_contiguous_reserve(limit 50000000)
[ 0.000000] cma: dma_contiguous_reserve: reserving 256 MiB for global area
[ 0.000000] cma: cma_declare_contiguous(size 10000000, base 00000000, limit 50000000 alignment 00000000)
[ 0.000000] cma: CMA: reserved 256 MiB at 40000000
[ 0.000000] Memory policy: Data cache writealloc
[ 0.000000] On node 0 totalpages: 262144
[ 0.000000] free_area_init_node: node 0, pgdat 807cf000, node_mem_map af777000
[ 0.000000] DMA zone: 2048 pages used for memmap
[ 0.000000] DMA zone: 0 pages reserved
[ 0.000000] DMA zone: 262144 pages, LIFO batch:31
[ 0.000000] PERCPU: Embedded 7 pages/cpu @af754000 s8192 r8192 d12288 u32768
[ 0.000000] pcpu-alloc: s8192 r8192 d12288 u32768 alloc=8*4096
[ 0.000000] pcpu-alloc: [0] 0 [0] 1
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 260096
[ 0.000000] Kernel command line: console=ttymxc0,115200,115200 quiet coherent_pool=180M root=/dev/mmcblk0p2 rootwait ro rootfstype=ext4
[ 0.000000] PID hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.000000] Dentry cache hash table entries: 131072 (order: 7, 524288 bytes)
[ 0.000000] Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
[ 0.000000] Memory: 768360K/1048576K available (5516K kernel code, 233K rwdata, 1876K rodata, 336K init, 399K bss, 280216K reserved, 0K highmem)
[ 0.000000] Virtual kernel memory layout:
vector : 0xffff0000 - 0xffff1000 ( 4 kB)
fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB)
vmalloc : 0xc0800000 - 0xff000000 (1000 MB)
lowmem : 0x80000000 - 0xc0000000 (1024 MB)
pkmap : 0x7fe00000 - 0x80000000 ( 2 MB)
modules : 0x7f000000 - 0x7fe00000 ( 14 MB)
.text : 0x80008000 - 0x80740534 (7394 kB)
.init : 0x80741000 - 0x80795000 ( 336 kB)
.data : 0x80796000 - 0x807d04a0 ( 234 kB)
.bss : 0x807d04a8 - 0x8083448c ( 400 kB)
[ 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=4 to nr_cpu_ids=2.
[ 0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=2
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] L2C-310 erratum 769419 enabled
[ 0.000000] L2C-310 enabling early BRESP for Cortex-A9
[ 0.000000] L2C-310 cache controller enabled, 16 ways, 512 kB
[ 0.000000] L2C-310: CACHE_ID 0x410000c8, AUX_CTRL 0x72450000
[ 0.000000] Switching to timer-based delay loop
[ 0.000008] sched_clock: 32 bits at 3000kHz, resolution 333ns, wraps every 1431655765682ns
[ 0.000980] Calibrating delay loop (skipped), value calculated using timer frequency.. 6.00 BogoMIPS (lpj=30000)
[ 0.000992] pid_max: default: 32768 minimum: 301
[ 0.001165] Mount-cache hash table entries: 2048 (order: 1, 8192 bytes)
[ 0.001175] Mountpoint-cache hash table entries: 2048 (order: 1, 8192 bytes)
[ 0.007102] CPU: Testing write buffer coherency: ok
[ 0.007371] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[ 0.007450] Setting up static identity map for 0x1053ef70 - 0x1053efc8
[ 0.008959] CPU1: Booted secondary processor
[ 0.008987] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[ 0.009096] Brought up 2 CPUs
[ 0.009107] SMP: Total of 2 processors activated (12.00 BogoMIPS).
[ 0.009112] CPU: All CPU(s) started in SVC mode.
[ 0.009757] devtmpfs: initialized
[ 0.013214] VFP support v0.3: implementor 41 architecture 3 part 30 variant 9 rev 4
[ 0.026956] pinctrl core: initialized pinctrl subsystem
[ 0.027224] regulator-dummy: no parameters
[ 0.027501] NET: Registered protocol family 16
[ 0.028182] cma: cma_alloc(cma 8081d358, count 46080, align 8)
[ 0.048082] cma: cma_alloc(): returned afd77000
[ 0.730786] DMA: preallocated 184320 KiB pool for atomic coherent allocations
[ 0.731204] cpuidle: using governor ladder
[ 0.731211] cpuidle: using governor menu
[ 0.731330] CPU identified as i.MX6DL, silicon rev 1.1
[ 0.731428] Use WDOG1 as reset source
[ 0.739809] syscon 20c8000.anatop: regmap [mem 0x020c8000-0x020c8fff] registered
[ 0.740120] vdd1p1: 800 <--> 1375 mV at 1100 mV
[ 0.740430] vdd3p0: 2800 <--> 3150 mV at 3000 mV
[ 0.740789] vdd2p5: 2000 <--> 2750 mV at 2400 mV
[ 0.741128] vddarm: 725 <--> 1450 mV at 1150 mV
[ 0.750683] vddpu: 725 <--> 1450 mV at 1150 mV
[ 0.751032] vddsoc: 725 <--> 1450 mV at 1175 mV
[ 0.753291] syscon 20e0000.iomuxc-gpr: regmap [mem 0x020e0000-0x020e0037] registered
[ 0.755630] syscon 21bc000.ocotp-ctrl: regmap [mem 0x021bc000-0x021bffff] registered
[ 0.759444] hw-breakpoint: found 5 (+1 reserved) breakpoint and 1 watchpoint registers.
[ 0.759452] hw-breakpoint: maximum watchpoint size is 4 bytes.
[ 0.761410] imx6dl-pinctrl 20e0000.iomuxc: initialized IMX pinctrl driver
[ 0.770481] bio: create slab <bio-0> at 0
[ 0.772859] mxs-dma 110000.dma-apbh: initialized
[ 0.773567] brcm_osc_reg: 3300 mV
[ 0.773828] brcm_reg: 3300 mV
[ 0.774027] 3P3V: 3300 mV
[ 0.774234] usb_otg_vbus: 5000 mV
[ 0.774490] reg_boost_aux: 5000 mV
[ 0.774760] reg_cam: 2800 mV
[ 0.775451] SCSI subsystem initialized
[ 0.775631] libata version 3.00 loaded.
[ 0.775880] usbcore: registered new interface driver usbfs
[ 0.775941] usbcore: registered new interface driver hub
[ 0.776035] usbcore: registered new device driver usb
[ 0.776192] usbphy_nop1.10 supply vcc not found, using dummy regulator
[ 0.776258] usbphy_nop2.11 supply vcc not found, using dummy regulator
[ 0.777491] i2c i2c-0: IMX I2C adapter registered
[ 0.777866] i2c i2c-1: IMX I2C adapter registered
[ 0.777974] Linux video capture interface: v2.00
[ 0.778018] pps_core: LinuxPPS API ver. 1 registered
[ 0.778023] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[ 0.778042] PTP clock support registered
[ 0.790721] imx-ipuv3 2400000.ipu: IPU DMFC NORMAL mode: 1(0~1), 5B(4,5), 5F(6,7)
[ 0.791800] mxc_mipi_csi2 21dc000.mipi_csi: i.MX MIPI CSI2 driver probed
[ 0.791811] mxc_mipi_csi2 21dc000.mipi_csi: i.MX MIPI CSI2 dphy version is 0x3130302a
[ 0.791874] MIPI CSI2 driver module loaded
[ 0.791942] Advanced Linux Sound Architecture Driver Initialized.
[ 0.792873] Switched to clocksource mxc_timer1
[ 0.794795] NET: Registered protocol family 2
[ 0.795497] TCP established hash table entries: 8192 (order: 3, 32768 bytes)
[ 0.795576] TCP bind hash table entries: 8192 (order: 4, 65536 bytes)
[ 0.795703] TCP: Hash tables configured (established 8192 bind 8192)
[ 0.795843] TCP: reno registered
[ 0.795855] UDP hash table entries: 512 (order: 2, 16384 bytes)
[ 0.795892] UDP-Lite hash table entries: 512 (order: 2, 16384 bytes)
[ 0.796150] NET: Registered protocol family 1
[ 0.796438] RPC: Registered named UNIX socket transport module.
[ 0.796444] RPC: Registered udp transport module.
[ 0.796448] RPC: Registered tcp transport module.
[ 0.796453] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.796908] hw perfevents: enabled with ARMv7 Cortex-A9 PMU driver, 7 counters available
[ 0.798888] Bus freq driver module loaded
[ 0.799778] futex hash table entries: 512 (order: 3, 32768 bytes)
[ 0.808299] zbud: loaded
[ 0.808637] VFS: Disk quotas dquot_6.5.2
[ 0.808935] Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[ 0.811123] NFS: Registering the id_resolver key type
[ 0.811162] Key type id_resolver registered
[ 0.811166] Key type id_legacy registered
[ 0.811398] fuse init (API version 7.22)
[ 0.811899] msgmni has been set to 2012
[ 0.814579] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 250)
[ 0.814589] io scheduler noop registered
[ 0.814593] io scheduler deadline registered
[ 0.814814] io scheduler cfq registered (default)
[ 0.816425] imx-sdma 20ec000.sdma: no iram assigned, using external mem
[ 0.816443] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 0.817803] cma: cma_alloc(): returned afedf000
[ 0.817851] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 0.818412] cma: cma_alloc(): returned afedf020
[ 0.818460] imx-sdma 20ec000.sdma: no event needs to be remapped
[ 0.818600] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 0.819179] cma: cma_alloc(): returned afedf040
[ 0.819292] cma: cma_release(page afedf040)
[ 0.819306] imx-sdma 20ec000.sdma: loaded firmware 3.1
[ 0.822617] imx-sdma 20ec000.sdma: initialized
[ 0.823223] Serial: IMX driver
[ 0.823492] 2020000.serial: ttymxc0 at MMIO 0x2020000 (irq = 58, base_baud = 5000000) is a IMX
[ 0.823637] console [ttymxc0] enabled
[ 0.824366] 21e8000.serial: ttymxc1 at MMIO 0x21e8000 (irq = 59, base_baud = 5000000) is a IMX
[ 0.824836] 21f0000.serial: ttymxc3 at MMIO 0x21f0000 (irq = 61, base_baud = 5000000) is a IMX
[ 0.825166] serial: Freescale lpuart driver
[ 0.826280] imx sema4 driver is registered.
[ 0.826321] [drm] Initialized drm 1.1.0 20060810
[ 0.826690] [drm] Initialized vivante 1.0.0 20120216 on minor 0
[ 0.834551] brd: module loaded
[ 0.838664] loop: module loaded
[ 0.840265] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 0.840342] usbcore: registered new interface driver usb-storage
[ 0.841090] 2184800.usbmisc supply vbus-wakeup not found, using dummy regulator
[ 0.844951] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 0.845655] cma: cma_alloc(): returned afedf040
[ 0.847848] mousedev: PS/2 mouse device common for all mice
[ 0.848631] silhouettestar2_rtc rtc.24: RTC-SilhouetteStar2 Probe
[ 0.848669] silhouettestar2_rtc rtc.24: RTC-SilhouetteStar2 Get Time
[ 0.848703] silhouettestar2_rtc rtc.24: RTC-SilhouetteStar2: file open error = -2
[ 0.855154] silhouettestar2_rtc rtc.24: rtc core: registered rtc.24 as rtc0
[ 0.855195] i2c /dev entries driver
[ 0.856658] imx2-wdt 20bc000.wdog: IMX2+ Watchdog Timer enabled. timeout=60s (nowayout=0)
[ 0.856898] sdhci: Secure Digital Host Controller Interface driver
[ 0.856902] sdhci: Copyright(c) Pierre Ossman
[ 0.856907] sdhci-pltfm: SDHCI platform and OF driver helper
[ 0.858740] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 0.859396] cma: cma_alloc(): returned afedf060
[ 0.859450] mmc1: no vqmmc regulator found
[ 1.162907] mmc1: SDHCI controller on 2190000.usdhc [2190000.usdhc] using ADMA
[ 1.165494] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 1.170216] cma: cma_alloc(): returned afedf080
[ 1.172928] mmc0: no vqmmc regulator found
[ 1.173269] 2194000.usdhc supply card-external-vcc not found, using dummy regulator
[ 1.186120] mmc1: queuing unknown CIS tuple 0x80 (2 bytes)
[ 1.187813] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[ 1.189509] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[ 1.192539] mmc1: queuing unknown CIS tuple 0x80 (7 bytes)
[ 1.195577] mmc1: queuing unknown CIS tuple 0x80 (7 bytes)
[ 1.245767] mmc1: new high speed SDIO card at address 0001
[ 1.272904] mmc0: SDHCI controller on 2194000.usdhc [2194000.usdhc] using ADMA
[ 1.273425] galcore: clk_get vg clock failed, disable vg!
[ 1.273446] Galcore version 5.0.11.25762
[ 1.322143] mmc0: host does not support reading read-only switch. assuming write-enable.
[ 1.329647] mmc0: new high speed SDHC card at address 0007
[ 1.330377] mmcblk0: mmc0:0007 SD08G 7.21 GiB
[ 1.334584] mmcblk0: p1 p2 p3 p4 < p5 p6 p7 >
[ 1.594994] mxc_vdoa 21e4000.vdoa: i.MX Video Data Order Adapter(VDOA) driver probed
[ 1.595518] mxc_vpu 2040000.vpu: VPU initialized
[ 1.596267] ledtrig-cpu: registered to indicate activity on CPUs
[ 1.843486] caam 2100000.caam: Instantiated RNG4 SH0
[ 2.087961] caam 2100000.caam: Instantiated RNG4 SH1
[ 2.087973] caam 2100000.caam: device ID = 0x0a160100 (Era 4)
[ 2.087983] caam 2100000.caam: job rings = 2, qi = 0
[ 2.088433] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 2.089464] cma: cma_alloc(): returned afedf160
[ 2.089504] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 2.090342] cma: cma_alloc(): returned afedf180
[ 2.113030] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 2.113915] cma: cma_alloc(): returned afedf1a0
[ 2.113953] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 2.114797] cma: cma_alloc(): returned afedf1c0
[ 2.145816] caam algorithms registered in /proc/crypto
[ 2.149413] caam_jr 2101000.jr0: registering rng-caam
[ 2.152441] snvs-secvio 20cc000.caam-snvs: violation handlers armed - non-secure state
[ 2.152733] usbcore: registered new interface driver usbhid
[ 2.152738] usbhid: USB HID core driver
[ 2.155249] TCP: cubic registered
[ 2.155950] NET: Registered protocol family 10
[ 2.156836] sit: IPv6 over IPv4 tunneling driver
[ 2.157536] NET: Registered protocol family 17
[ 2.157597] 8021q: 802.1Q VLAN Support v1.8
[ 2.157647] Key type dns_resolver registered
[ 2.158776] Registering SWP/SWPB emulation handler
[ 2.159338] reg_cam: disabling
[ 2.159354] regulator-dummy: disabling
[ 2.159603] imx mcc test is registered.
[ 2.159961] silhouettestar2_rtc rtc.24: RTC-SilhouetteStar2 Get Time
[ 2.159997] silhouettestar2_rtc rtc.24: RTC-SilhouetteStar2: file open error = -2
[ 2.166212] silhouettestar2_rtc rtc.24: hctosys: unable to read the hardware clock
[ 2.174066] ALSA device list:
[ 2.174070] No soundcards found.
[ 2.193357] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[ 2.193388] VFS: Mounted root (ext4 filesystem) readonly on device 179:2.
[ 2.197512] devtmpfs: mounted
[ 2.198079] Freeing unused kernel memory: 336K (80741000 - 80795000)
[ 2.430273] random: systemd: uninitialized urandom read (16 bytes read, 21 bits of entropy available)
[ 2.443943] systemd[1]: systemd 219 running in system mode. (-PAM -AUDIT -SELINUX +IMA -APPARMOR +SMACK +SYSVINIT +UTMP -LIBCRYPTSETUP -GCRYPT -GNUTLS +ACL +XZ -LZ4 -SECCOMP +BLKID -ELFUTILS +KMOD -IDN)
[ 2.444442] systemd[1]: Detected architecture arm.
[ 2.445565] systemd[1]: Set hostname to <SilhouetteStar_2010-01_L16X00000>.
[ 2.452569] random: systemd: uninitialized urandom read (16 bytes read, 21 bits of entropy available)
[ 2.452687] systemd[1]: Initializing machine ID from random generator.
[ 2.453256] systemd[1]: Installed transient /etc/machine-id file.
[ 2.466457] random: systemd: uninitialized urandom read (16 bytes read, 21 bits of entropy available)
[ 2.495941] random: systemd-sysv-ge: uninitialized urandom read (16 bytes read, 22 bits of entropy available)
[ 2.559118] random: systemd: uninitialized urandom read (16 bytes read, 24 bits of entropy available)
[ 2.559338] random: systemd: uninitialized urandom read (16 bytes read, 24 bits of entropy available)
[ 2.560660] random: systemd: uninitialized urandom read (16 bytes read, 24 bits of entropy available)
[ 2.560977] random: systemd: uninitialized urandom read (16 bytes read, 24 bits of entropy available)
[ 2.561545] random: systemd: uninitialized urandom read (16 bytes read, 24 bits of entropy available)
[ 2.566338] random: systemd: uninitialized urandom read (16 bytes read, 24 bits of entropy available)
[ 2.694349] systemd[1]: Cannot add dependency job for unit org.freedesktop.resolve1.busname, ignoring: Unit org.freedesktop.resolve1.busname failed to load: No such file or directory.
[ 2.697889] systemd[1]: Started Forward Password Requests to Wall Directory Watch.
[ 2.697956] systemd[1]: Starting Forward Password Requests to Wall Directory Watch.
[ 2.698137] systemd[1]: Reached target Remote File Systems.
[ 2.698192] systemd[1]: Starting Remote File Systems.
[ 2.698407] systemd[1]: Created slice Root Slice.
[ 2.698467] systemd[1]: Starting Root Slice.
[ 2.698705] systemd[1]: Listening on Journal Socket (/dev/log).
[ 2.698763] systemd[1]: Starting Journal Socket (/dev/log).
[ 2.698974] systemd[1]: Listening on Journal Socket.
[ 2.699052] systemd[1]: Starting Journal Socket.
[ 2.699212] systemd[1]: Listening on Syslog Socket.
[ 2.699265] systemd[1]: Starting Syslog Socket.
[ 2.719414] systemd[1]: Listening on Journal Audit Socket.
[ 2.719659] systemd[1]: Listening on udev Kernel Socket.
[ 2.719721] systemd[1]: Starting udev Kernel Socket.
[ 2.719986] systemd[1]: Listening on /dev/initctl Compatibility Named Pipe.
[ 2.720046] systemd[1]: Starting /dev/initctl Compatibility Named Pipe.
[ 2.720262] systemd[1]: Listening on udev Control Socket.
[ 2.720319] systemd[1]: Starting udev Control Socket.
[ 2.720707] systemd[1]: Listening on networkd rtnetlink socket.
[ 2.720767] systemd[1]: Starting networkd rtnetlink socket.
[ 2.721055] systemd[1]: Created slice System Slice.
[ 2.721138] systemd[1]: Starting System Slice.
[ 2.722708] systemd[1]: Starting Journal Service...
[ 2.723314] systemd[1]: Mounted Debug File System.
[ 2.723825] systemd[1]: Mounted Huge Pages File System.
[ 2.724328] systemd[1]: Created slice system-serial\x2dgetty.slice.
[ 2.724394] systemd[1]: Starting system-serial\x2dgetty.slice.
[ 2.728044] systemd[1]: Started Load Kernel Modules.
[ 2.728352] systemd[1]: Mounted Configuration File System.
[ 2.729944] systemd[1]: Starting Apply Kernel Variables...
[ 2.732610] systemd[1]: Mounting FUSE Control File System...
[ 2.733011] systemd[1]: Mounted POSIX Message Queue File System.
[ 2.736793] systemd[1]: Starting udev Coldplug all Devices...
[ 2.737450] systemd[1]: Created slice system-getty.slice.
[ 2.737564] systemd[1]: Starting system-getty.slice.
[ 2.739864] systemd[1]: Starting Create list of required static device nodes for the current kernel...
[ 2.740495] systemd[1]: Created slice system-systemd\x2dfsck.slice.
[ 2.740614] systemd[1]: Starting system-systemd\x2dfsck.slice.
[ 2.743319] systemd[1]: Starting Remount Root and Kernel File Systems...
[ 2.775409] systemd[1]: Mounting Temporary Directory...
[ 2.778634] systemd[1]: Created slice User and Session Slice.
[ 2.778700] systemd[1]: Starting User and Session Slice.
[ 2.778800] systemd[1]: Started Setup Virtual Console.
[ 2.779737] systemd[1]: Started Dispatch Password Requests to Console Directory Watch.
[ 2.779797] systemd[1]: Starting Dispatch Password Requests to Console Directory Watch.
[ 2.779877] systemd[1]: Reached target Paths.
[ 2.779918] systemd[1]: Starting Paths.
[ 2.780229] systemd[1]: Created slice system-wpa_supplicant.slice.
[ 2.780276] systemd[1]: Starting system-wpa_supplicant.slice.
[ 2.780472] systemd[1]: Listening on Delayed Shutdown Socket.
[ 2.780518] systemd[1]: Starting Delayed Shutdown Socket.
[ 2.780604] systemd[1]: Reached target Swap.
[ 2.780647] systemd[1]: Starting Swap.
[ 2.780729] systemd[1]: Reached target Slices.
[ 2.780772] systemd[1]: Starting Slices.
[ 2.781935] systemd[1]: Started Create list of required static device nodes for the current kernel.
[ 2.793687] systemd[1]: Mounted FUSE Control File System.
[ 2.793859] systemd[1]: Mounted Temporary Directory.
[ 2.823354] systemd[1]: Started Apply Kernel Variables.
[ 2.834004] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[ 2.862172] systemd[1]: Started Remount Root and Kernel File Systems.
[ 2.882042] systemd[1]: Started udev Coldplug all Devices.
[ 2.958417] systemd[1]: Started Rebuild Hardware Database.
[ 2.958548] systemd[1]: Started First Boot Wizard.
[ 2.958620] systemd[1]: Started Create System Users.
[ 2.960200] systemd[1]: Starting Create Static Device Nodes in /dev...
[ 2.960396] systemd[1]: Started Rebuild Dynamic Linker Cache.
[ 2.996235] systemd[1]: Started Journal Service.
[ 3.498541] mxc_v4l_open: Mxc Camera no sensor ipu0/csi0
[ 3.635806] cfg80211: Calling CRDA to update world regulatory domain
[ 3.816727] random: nonblocking pool is initialized
[ 3.881444] brcmfmac: brcmf_c_preinit_dcmds: Firmware version = wl0: Jan 23 2013 17:47:32 version 5.90.195.114 FWID 01-f9e7e464
[ 4.188236] EXT4-fs (mmcblk0p7): mounted filesystem with ordered data mode. Opts: (null)
[ 4.377138] systemd-journald[144]: Received request to flush runtime journal from PID 1
[ 4.534245] EXT4-fs (mmcblk0p6): mounted filesystem with ordered data mode. Opts: (null)
[ 4.933892] using random self ethernet address
[ 4.933906] using random host ethernet address
[ 4.934572] usb0: HOST MAC 6e:9f:55:e3:b3:86
[ 4.934626] usb0: MAC 9a:2d:f9:b9:90:d9
[ 4.934659] using random self ethernet address
[ 4.934668] using random host ethernet address
[ 4.934708] g_ether gadget: Ethernet Gadget, version: Memorial Day 2008
[ 4.934714] g_ether gadget: g_ether ready
[ 5.337972] IPv6: ADDRCONF(NETDEV_UP): usb0: link is not ready
[ 5.982973] mxc_v4l2_master_attach: ipu0:/csi0 mipi attached ov5640_mipi:mxc_v4l2_cap0
[ 5.983000] camera ov5640_mipi is found
[ 8.459218] g_ether gadget: high-speed config #1: CDC Ethernet (ECM)
[ 8.460691] IPv6: ADDRCONF(NETDEV_CHANGE): usb0: link becomes ready
[ 11.674988] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 11.676195] cma: cma_alloc(): returned afedf1e0
[ 11.676250] cma: cma_alloc(cma 8081d358, count 20, align 5)
[ 11.676940] cma: cma_alloc(): returned afedf400
[ 11.677386] cma: cma_alloc(cma 8081d358, count 1, align 0)
[ 11.678082] cma: cma_alloc(): returned afedf200