I'm using ATLYS board. I got linux from here:
git clone git://git.openrisc.net/jonas/linux

I cannot get the Linux prompt:
==> bootm 100000
## Booting kernel from Legacy Image at 00100000 ...
Image Name: Linux for OpenRISC
Image Type: OpenRISC 1000 Linux Kernel Image (uncompressed)
Data Size: 4084236 Bytes = 3.9 MiB
Load Address: 00000000
Entry Point: 00000100
Verifying Checksum ... OK
Loading Kernel Image ... OK
OK

stop here!!


Here is my steps:
1. export CROSS_COMPILE=or32-elf-
2. create atlys.dts
3. "make menuconfig" to change or1ksim to atlys
4. make
5. ~/u-boot/tools/mkimage -n 'Linux for OpenRISC' -A or1k -O linux -T kernel -C none -a 0 -e 0x100 -d ~/OpenRISC/linux/vmlinux.bin /tftpboot/uImage

My questions:
1. We should export CROSS_COMPILE=or32-elf- or CROSS_COMPILE=or32-linux- ?
2. After I type make(step4), vmlinux is generated, but vmlinux.bin is not. Should I manually use "or32-elf-objcopy -O binary vmlinux vmlinux.bin"?

UPDATE

RESULT OF gtkterm (/dev/ttyACM0)

==> bootm 100000
## Booting kernel from Legacy Image at 00100000 ...
Image Name: Linux for OpenRISC
Image Type: OpenRISC 1000 Linux Kernel Image (uncompressed)
Data Size: 4084268 Bytes = 3.9 MiB
Load Address: 00000000
Entry Point: 00000100
Verifying Checksum ... OK
Loading Kernel Image ... OK
OK
Compiled-in FDT at c029c1e0
Linux version 3.9.0-dirty (vbtt@vbtt-MacBookPro) (gcc version 4.5.1-or32-1.0rc4 (OpenRISC 32-bit toolchain for or32-elf (built 20130405)) ) #4 Fri Jul 5 11:07:24 CST 2013
CPU: OpenRISC-12 (revision 8) @50 MHz
-- dcache: 32768 bytes total, 32 bytes/line, 1 way(s)
-- icache: 32768 bytes total, 32 bytes/line, 1 way(s)
-- dmmu: 64 entries, 1 way(s)
-- immu: 64 entries, 1 way(s)
-- additional features:
-- debug unit
-- PIC
-- timer
setup_memory: Memory: 0x0-0x8000000
Reserved - 0x07ffda90-0x00002570
Setting up paging and PTEs.
map_ram: Memory: 0x0-0x8000000
itlb_miss_handler c0002198
dtlb_miss_handler c0002000
OpenRISC Linux -- http://openrisc.net
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 16320
Kernel command line: console=uart,mmio,0x90000000,115200
Early serial console at MMIO 0x90000000 (options '11520')
bootconsole [uart0] enabled
PID hash table entries: 512 (order: -2, 2048 bytes)
Dentry cache hash table entries: 16384 (order: 3, 65536 bytes)
Inode-cache hash table entries: 8192 (order: 2, 32768 bytes)
Memory: 126248k/131072k available (2227k kernel code, 4824k reserved, 338k data, 1416k init, 0k highmem)
mem_init_done ...........................................
NR_IRQS:32 nr_irqs:32 0
100.00 BogoMIPS (lpj=500000)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 1024
devtmpfs: initialized
NET: Registered protocol family 16
Switching to clocksource openrisc_timer
NET: Registered protocol family 2
TCP established hash table entries: 1024 (order: 0, 8192 bytes)
TCP bind hash table entries: 1024 (order: -1, 4096 bytes)
TCP: Hash tables configured (established 1024 bind 1024)
TCP: reno registered
UDP hash table entries: 512 (order: 0, 8192 bytes)
UDP-Lite hash table entries: 512 (order: 0, 8192 bytes)
NET: Registered protocol family 1
RPC: Registered named UNIX socket transport module.
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
RPC: Registered tcp NFSv4.1 backchannel transport module.
Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
90000000.serial: ttyS0 at MMIO 0x90000000 (irq = 2) is a 16550A

Stop here! no linux prompt

I think the reason is ttyS0. It should be ttyACM0, right?

There is a bug in the 3.9 kernel causing the baudrate to be incorrectly read from the kernel command line options.
You can get around this by either:
1) apply this patch: https://patchwork.kernel.org/patch/2821521/

or
2) use:
earlycon=uart,mmio,0x90000000,115200 console=ttyS0,115200
instead of:
console=uart,mmio,0x90000000,115200

or
3) use a kernel version prior to 3.9

Stefan