kernel: linux-3.14.43
platform:AM437X
问题：用uboot的 tftp命令下载kernel，启动后无打印信息
tftp操作步骤：
step1: tftp 0x82000000 uImage
step2: tftp 0x83000000 am437x-gp-easyevm.dtb
step3: bootm 0x82000000 - 0x83000000
打印信息如下
U-Boot# U-Boot# U-Boot# U-Boot# tftp 0x82000000 uImage link up on port 0, speed 1000, full duplex Using cpsw device TFTP from server 192.168.65.106; our IP address is 192.168.65.249 Filename 'uImage'. Load address: 0x82000000 Loading: ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ##################################################### 178.7 KiB/s done Bytes transferred = 4593440 (461720 hex) U-Boot# tftp 0x83000000 am437x-gp-easyevm.dtb link up on port 0, speed 1000, full duplex Using cpsw device TFTP from server 192.168.65.106; our IP address is 192.168.65.249 Filename 'am437x-gp-easyevm.dtb'. Load address: 0x83000000 Loading: ########## 196.3 KiB/s done Bytes transferred = 50739 (c633 hex) U-Boot# bootm 0x82000000 - 0x83000000 ## Booting kernel from Legacy Image at 82000000 ... Image Name: Linux-3.14.43 Image Type: ARM Linux Kernel Image (uncompressed) Data Size: 4593376 Bytes = 4.4 MiB Load Address: 80008000 Entry Point: 80008000 Verifying Checksum ... OK ## Flattened Device Tree blob at 83000000 Booting using the fdt blob at 0x83000000 Loading Kernel Image ... OK Loading Device Tree to 8fff0000, end 8ffff632 ... OK Starting kernel ... _____ _____ _ _ | _ |___ ___ ___ ___ | _ |___ ___ |_|___ ___| |_ | | _| .'| . | . | | __| _| . | | | -_| _| _| |__|__|_| |__,|_ |___| |__| |_| |___|_| |___|___|_| |___| |___| Arago Project http://arago-project.org am437x-evm /dev/ttyO0 Arago 2015.05 am437x-evm /dev/ttyO0 am437x-evm login: root root@am437x-evm:~#
而直接从nand启动就有kernel的打印信息
U-Boot SPL 2014.07-00115-g6c69db3 (Jan 30 2016 - 17:32:22)
Could not probe the EEPROM at 0x50
Could not get board ID.
SPL: Please implement spl_start_uboot() for your board
SPL: Direct Linux boot not active!
U-Boot 2014.07-00115-g6c69db3 (Jan 30 2016 - 17:32:22) I2C: ready DRAM: 512 MiB NAND: 512 MiB MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1 reading uboot.env Could not probe the EEPROM at 0x50 Could not get board ID. Net: cpsw, usb_ether Hit any key to stop autoboot: 0 switch to partitions #0, OK mmc0 is current device SD/MMC found on device 0 reading uEnv.txt ** Unable to read file uEnv.txt ** 4576224 bytes read in 212 ms (20.6 MiB/s) 50683 bytes read in 9 ms (5.4 MiB/s) Booting from mmc0 ... Kernel image @ 0x82000000 [ 0x000000 - 0x45d3e0 ] ## Flattened Device Tree blob at 88000000 Booting using the fdt blob at 0x88000000 Loading Device Tree to 8fff0000, end 8ffff5fa ... OK Starting kernel ... [ 0.000000] Booting Linux on physical CPU 0x0 [ 0.000000] Linux version 3.14.43 (zxp@zxp) (gcc version 4.7.3 20130226 (prerelease) (crosstool-NG linaro-1.13.1-4.7-2013.03-20130313 - Linaro GCC 2013.03) ) #1 Fri Sep 9 16:13:52 CST 2016 [ 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: TI AM437x GP EVM [ 0.000000] cma: CMA: reserved 24 MiB at 9e400000 [ 0.000000] Memory policy: Data cache writeback [ 0.000000] CPU: All CPU(s) started in SVC mode. [ 0.000000] AM437x ES1.2 (sgx neon ) [ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 129536 [ 0.000000] Kernel command line: console=ttyO0,115200n8 root=/dev/mmcblk0p2 rw rootfstype=ext4 rootwait [ 0.000000] PID hash table entries: 2048 (order: 1, 8192 bytes) [ 0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes) [ 0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes) [ 0.000000] Memory: 483656K/522240K available (6215K kernel code, 312K rwdata, 2212K rodata, 269K init, 233K bss, 38584K reserved, 0K highmem) [ 0.000000] Virtual kernel memory layout: [ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB) [ 0.000000] fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB) [ 0.000000] vmalloc : 0xe0800000 - 0xff000000 ( 488 MB) [ 0.000000] lowmem : 0xc0000000 - 0xe0000000 ( 512 MB) [ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB) [ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB) [ 0.000000] .text : 0xc0008000 - 0xc08430c4 (8429 kB) [ 0.000000] .init : 0xc0844000 - 0xc08874cc ( 270 kB) [ 0.000000] .data : 0xc0888000 - 0xc08d6200 ( 313 kB) [ 0.000000] .bss : 0xc08d6200 - 0xc0910890 ( 234 kB) [ 0.000000] NR_IRQS:16 nr_irqs:16 16 [ 0.000000] GIC CPU mask not found - kernel will fail to boot. [ 0.000000] GIC CPU mask not found - kernel will fail to boot. [ 0.000000] OMAP clockevent source: timer2
