My Linux kernel image uImage is in my U-disk. And I want to boot it from U-Boot. Also the device tree file am335x-evm.dtb is in my U-disk.
What I did is below:
U-Boot# usb start
(Re)start USB...
USB0: scanning bus 0 for devices... 1 USB Device(s) found
scanning usb for storage devices... 1 Storage Device(s) found
U-Boot# fatls usb 0:1
3821960 uimage
kit3/
4065280 modules.tar
my_modules/
extra/
system volume information/
375 uenv.txt
40474 am335x-evm.dtb
4 file(s), 4 dir(s)
U-Boot# fatload usb 0:1 0xC0700000 uImage
reading uImage
3821960 bytes read in 2375 ms (1.5 MiB/s)
U-Boot# fatload usb 0:1 0xC0e00000 am335x-evm.dtb
reading am335x-evm.dtb
40474 bytes read in 48 ms (823.2 KiB/s)
U-Boot# bootm 0xC0700000 - 0xC0e00000
## Booting kernel from Legacy Image at c0700000 ...
Image Name: Linux-3.12.10-ge35dc10-dirty
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 3821896 Bytes = 3.6 MiB
Load Address: 80008000
Entry Point: 80008000
Verifying Checksum ... OK
## Flattened Device Tree blob at c0e00000
Booting using the fdt blob at 0xc0e00000
Loading Kernel Image ... OK
OK
Using Device Tree in place at c0e00000, end c0e0ce19
Starting kernel ...
And it stops here. How to do? Thanks!
Result: Thanks for everyone who answered in this post! Now I can boot the system by using the image in U-disk. What I do is:
setenv bootargs "console=ttyO0,115200n8 root=/dev/mmcblk0p2 rw rootfstype=ext4 mem=512M coherent_pool=8M loglevel=0 lpj=3317760 rootwait"
usb start; fatls usb 0:1; fatload usb 0:1 0x82000000 uImage-orig-onUSB;fatload usb 0:1 0x80F80000 am335x-evm.dtb;bootm 0x82000000 - 0x80F80000
Without the first sentence, the system can also boot and start the GUI program which will show in a display. But the debug serial port has no reaction any more!
As for the second sentence, if I use the ram address of 0xC0700000 and 0xC0e00000, like this below, then it will stop to load the kernel. The reason should be what sawdust mentioned in his answer. @sawdust
setenv bootargs "console=ttyO0,115200n8 root=/dev/mmcblk0p2 rw rootfstype=ext4 mem=512M coherent_pool=8M loglevel=0 lpj=3317760 rootwait"
usb start; fatls usb 0:1; fatload usb 0:1 0xC0700000 uImage-orig-onUSB;fatload usb 0:1 0xC0e00000 am335x-evm.dtb;bootm 0xC0700000 - 0xC0e00000
Despite the message "Starting kernel ...", the kernel has not actually started executing (because the image has to be first relocated and also uncompressed), and consequently enabling earlyprintk will have no effect yet.
What does look suspect are the RAM addresses.
The typical "am33xx-evm" board only has 512MB of RAM starting at 0x80000000.
Yet you are trying to use RAM addresses from 0xC0700000 to 0xC0E0CE19 where physical memory should not exist.
Obviously the kernel and the device tree are not loaded properly.
Instead of
fatload usb 0:1 0xC0700000 uImage
fatload usb 0:1 0xC0e00000 am335x-evm.dtb
bootm 0xC0700000 - 0xC0e00000
try using
fatload usb 0:1 0x80200000 uImage
fatload usb 0:1 0x80e00000 am335x-evm.dtb
bootm 0x80200000 - 0x80e00000