想优化linux启动速度，看打印信息
在[ 0.327926] 1c28000.serial: ttyS0 at MMIO 0x1c28000 (irq = 99, base_baud = 1500000) is a U6_16550A
耗时较长， 请问这里有什么问题吗？能不能优化？
U-Boot SPL 2022.07 (Oct 18 2022 - 14:34:38 +0800)
DRAM: 64 MiB
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 5.19.9-c3130 (yss@yw) (arm-linux-gnueabihf-gcc (Linaro GCC 7.5-2019.12) 7.5.0, GNU ld (Lin2
[ 0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=10c5387d
[ 0.000000] CPU: div instructions available: patching division code
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] OF: fdt: Machine model: Lichee Pi Zero
[ 0.000000] Memory policy: Data cache writealloc
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x0000000040000000-0x0000000043ffffff]
[ 0.000000] HighMem empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000040000000-0x0000000043ffffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000040000000-0x0000000043ffffff]
[ 0.000000] psci: probing for conduit method from DT.
[ 0.000000] psci: Using PSCI v0.1 Function IDs from DT
[ 0.000000] percpu: Embedded 11 pages/cpu s15444 r8192 d21420 u45056
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 16256
[ 0.000000] Kernel command line: console=ttyS0,115200 panic=5 rootwait root=/dev/mmcblk0p2 earlyprintk rw vt.global_0
[ 0.000000] Unknown kernel command line parameters "earlyprintk", will be passed to user space.
[ 0.000000] Dentry cache hash table entries: 8192 (order: 3, 32768 bytes, linear)
[ 0.000000] Inode-cache hash table entries: 4096 (order: 2, 16384 bytes, linear)
[ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[ 0.000000] Memory: 53592K/65536K available (7168K kernel code, 690K rwdata, 1772K rodata, 1024K init, 293K bss, 119)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] rcu: Hierarchical RCU implementation.
[ 0.000000] rcu: RCU event tracing is enabled.
[ 0.000000] rcu: RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=1.
[ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
[ 0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
[ 0.000000] NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
[ 0.000000] GIC: Using split EOI/Deactivate mode
[ 0.000000] rcu: srcu_init: Setting srcu_struct sizes based on contention.
[ 0.000000] arch_timer: cp15 timer(s) running at 24.00MHz (phys).
[ 0.000000] clocksource: arch_sys_counter: mask: 0xffffffffffffff max_cycles: 0x588fe9dc0, max_idle_ns: 440795202592s
[ 0.000002] sched_clock: 56 bits at 24MHz, resolution 41ns, wraps every 4398046511097ns
[ 0.000016] Switching to timer-based delay loop, resolution 41ns
[ 0.000225] clocksource: timer: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635851949 ns
[ 0.000613] Console: colour dummy device 80x30
[ 0.000686] Calibrating delay loop (skipped), value calculated using timer frequency.. 48.00 BogoMIPS (lpj=240000)
[ 0.000709] pid_max: default: 32768 minimum: 301
[ 0.000947] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.000971] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.001783] CPU: Testing write buffer coherency: ok
[ 0.002341] /cpus/cpu@0 missing clock-frequency property
[ 0.002387] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[ 0.003756] Setting up static identity map for 0x40100000 - 0x40100060
[ 0.004045] rcu: Hierarchical SRCU implementation.
[ 0.004058] rcu: Max phase no-delay instances is 1000.
[ 0.004858] smp: Bringing up secondary CPUs ...
[ 0.004880] smp: Brought up 1 node, 1 CPU
[ 0.004890] SMP: Total of 1 processors activated (48.00 BogoMIPS).
[ 0.004901] CPU: All CPU(s) started in HYP mode.
[ 0.004904] CPU: Virtualization extensions available.
[ 0.005748] devtmpfs: initialized
[ 0.009624] VFP support v0.3: implementor 41 architecture 2 part 30 variant 7 rev 5
[ 0.010020] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[ 0.010060] futex hash table entries: 256 (order: 2, 16384 bytes, linear)
[ 0.010290] pinctrl core: initialized pinctrl subsystem
[ 0.011959] NET: Registered PF_NETLINK/PF_ROUTE protocol family
[ 0.013716] thermal_sys: Registered thermal governor 'step_wise'
[ 0.014072] hw-breakpoint: found 5 (+1 reserved) breakpoint and 4 watchpoint registers.
[ 0.014094] hw-breakpoint: maximum watchpoint size is 8 bytes.
[ 0.017804] platform 1c0c000.lcd-controller: Fixing up cyclic dependency with 1100000.mixer
[ 0.023367] platform panel: Fixing up cyclic dependency with 1c0c000.lcd-controller
[ 0.033663] SCSI subsystem initialized
[ 0.033864] usbcore: registered new interface driver usbfs
[ 0.033928] usbcore: registered new interface driver hub
[ 0.033990] usbcore: registered new device driver usb
[ 0.034263] mc: Linux media interface: v0.10
[ 0.034302] videodev: Linux video capture interface: v2.00
[ 0.036021] clocksource: Switched to clocksource arch_sys_counter
[ 0.049311] NET: Registered PF_INET protocol family
[ 0.049625] IP idents hash table entries: 2048 (order: 2, 16384 bytes, linear)
[ 0.050642] tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 4096 bytes, linear)
[ 0.050692] Table-perturb hash table entries: 65536 (order: 6, 262144 bytes, linear)
[ 0.050710] TCP established hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.050735] TCP bind hash table entries: 1024 (order: 1, 8192 bytes, linear)
[ 0.050760] TCP: Hash tables configured (established 1024 bind 1024)
[ 0.050903] UDP hash table entries: 256 (order: 1, 8192 bytes, linear)
[ 0.050960] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes, linear)
[ 0.051309] NET: Registered PF_UNIX/PF_LOCAL protocol family
[ 0.052624] Initialise system trusted keyrings
[ 0.053925] workingset: timestamp_bits=30 max_order=14 bucket_order=0
[ 0.160663] Key type asymmetric registered
[ 0.160694] Asymmetric key parser 'x509' registered
[ 0.160936] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 250)
[ 0.160954] io scheduler mq-deadline registered
[ 0.160961] io scheduler kyber registered
[ 0.244254] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
[ 0.250277] panel-simple panel: supply power not found, using dummy regulator
[ 0.250591] panel-simple panel: Specify missing connector_type
[ 0.252651] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 0.252677] ehci-platform: EHCI generic platform driver
[ 0.252806] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[ 0.252842] ohci-platform: OHCI generic platform driver
[ 0.253044] usbcore: registered new interface driver usb-storage
[ 0.255106] sun6i-rtc 1c20400.rtc: registered as rtc0
[ 0.255196] sun6i-rtc 1c20400.rtc: setting system clock to 1970-01-01T02:40:17 UTC (9617)
[ 0.255381] sun6i-rtc 1c20400.rtc: RTC enabled
[ 0.255632] i2c_dev: i2c /dev entries driver
[ 0.256757] sunxi-wdt 1c20ca0.watchdog: Watchdog enabled (timeout=16 sec, nowayout=0)
[ 0.257885] sun4i-ss 1c15000.crypto: Die ID 7
[ 0.258797] usbcore: registered new interface driver usbhid
[ 0.258815] usbhid: USB HID core driver
[ 0.259421] Initializing XFRM netlink socket
[ 0.259466] NET: Registered PF_PACKET protocol family
[ 0.260170] Registering SWP/SWPB emulation handler
[ 0.260494] Loading compiled-in X.509 certificates
[ 0.276459] sun8i-v3s-pinctrl 1c20800.pinctrl: initialized sunXi PIO driver
[ 0.276902] sun8i-v3s-pinctrl 1c20800.pinctrl: supply vcc-pb not found, using dummy regulator
[ 0.277667] pwm-backlight backlight: supply power not found, using dummy regulator
[ 0.307600] printk: console [ttyS0] disabled
[ 0.327926] 1c28000.serial: ttyS0 at MMIO 0x1c28000 (irq = 99, base_baud = 1500000) is a U6_16550A
[ 1.044357] printk: console [ttyS0] enabled
[ 1.049755] sun8i-v3s-pinctrl 1c20800.pinctrl: supply vcc-pe not found, using dummy regulator
[ 1.082509] sun4i-drm display-engine: bound 1100000.mixer (ops 0xc084b480)
[ 1.090335] sun4i-drm display-engine: bound 1c0c000.lcd-controller (ops 0xc0847f84)
[ 1.099338] [drm] Initialized sun4i-drm 1.0.0 20150629 for display-engine on minor 0
[ 1.151464] Console: switching to colour frame buffer device 100x30
[ 1.176319] sun4i-drm display-engine: [drm] fb0: sun4i-drmdrmfb frame buffer device离线
某处死锁等超时了,有一个偏方就是波尔率拉到1500000就快了
离线
还有个偏方是直接关掉串口，:P
离线