升级pb44方案内核---第一章（内核启动）
atheros原有的pb44方案对应的内核版本为2.6.15，该版本的内核在开启NAT的情况下，会出现kernel dump。该问题目前还没有好的解决方法。大致的思路是升级内核版本到2.6.31版本。该版本的内核在db12x方案上验证nat正常。下面就记个移植的流水账。
1.使用最高版本SDK的中pb47-xmii-2.6.31为配置文件，编译出demo程序，用原有boot启动，出现无法启动的问题，后对比2.6.15内核，发现vmlinux.info的link地址不同，修改为相同就能启动。
2.下载命令
load -r -v -b 0x80500000 vmlinux.bin.gz
fis create -b 0x80500000 -f 0xBF040000 -l 0x200000 -e 0x802468a0 -r 0x80060000 vmlinux
fis load -d vmlinux
exec
3.启动日志：
RedBoot> exec
Now booting linux kernel:
Base address 0x80050000 Entry 0x802468a0
Cmdline : console=ttyS0,115200 root=31:02 rootfstype=jffs2 init=/sbin/init
Booting Atheros AR7100 (hydra)....
==> : CPU 680 MHz AHB 170 MHz DDR 340 MHz
Linux version 2.6.31--LSDK-9.5.5.36 (root@xiaobingjian-desktop) (gcc version 4.3.3 (GCC) ) #1 Thu Jul 24 16:25:34 CST 2014
flash_size passed from bootloader = 16
arg 1: console=ttyS0,115200 root=31:02 rootfstype=jffs2 init=/sbin/init
CPU revision is: 00019374 (MIPS 24Kc)
Determined physical RAM map:
memory: 02000000 @ 00000000 (usable)
Zone PFN ranges:
Normal 0x00000000 -> 0x00002000
Movable zone start PFN for each node
early_node_map[1] active PFN ranges
0: 0x00000000 -> 0x00002000
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 8128
Kernel command line: console=ttyS0,115200 root=31:02 rootfstype=jffs2 init=/sbin/init
PID hash table entries: 128 (order: 7, 512 bytes)
Dentry cache hash table entries: 4096 (order: 2, 16384 bytes)
Inode-cache hash table entries: 2048 (order: 1, 8192 bytes)
Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
Primary data cache 32kB, 4-way, VIPT, cache aliases, linesize 32 bytes
Writing ErrCtl register=00000002
Readback ErrCtl register=00000002
Memory: 29348k/32768k available (1965k kernel code, 3420k reserved, 544k data, 140k init, 0k highmem)
NR_IRQS:128
plat_time_init: plat time init done : freq 340000000
r4k_clockevent_init: Ignoring int_usable failure
Console: colour dummy device 80x25
Calibrating delay loop... 452.60 BogoMIPS (lpj=905216)
Mount-cache hash table entries: 512
NET: Registered protocol family 16
PCI init:ar7100_pcibios_init
ar7100_pcibios_init(222): PCI CMD write: 0x356
registering PCI controller with io_map_base unset
arch/mips/ar7100/gpio.c (pbXX_simple_config_init) JUMPSTART_GPIO: 3
jumpstart_irq Enter
bio: create slab
SCSI subsystem initialized
pci 0000:00:00.0: PME# supported from D0 D3hot
pci 0000:00:00.0: PME# disabled
pci 0000:00:01.0: PME# supported from D0 D3hot
pci 0000:00:01.0: PME# disabled
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
Switched to NOHz mode on CPU #0
TCP established hash table entries: 1024 (order: 1, 8192 bytes)
TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
TCP: Hash tables configured (established 1024 bind 1024)
TCP reno registered
NET: Registered protocol family 1
AR7100 GPIOC major 0
JFFS2 version 2.2 (NAND) (ZLIB) (RTIME) (c) 2001-2006 Red Hat, Inc.
msgmni has been set to 57
Block layer SCSI generic (bsg) driver version 0.4 loaded (major 254)
io scheduler noop registered
io scheduler deadline registered (default)
Serial: 8250/16550 driver, 1 ports, IRQ sharing disabled
serial8250.0: ttyS0 at MMIO 0xb8020000 (irq = 19) is a 16550A
console [ttyS0] enabled
brd: module loaded
RedBoot partition parsing not available
No partitions found on flash bank 0
TCP cubic registered
NET: Registered protocol family 17
802.1Q VLAN Support v1.8 Ben Greear
All bugs added by David S. Miller
VFS: Cannot open root device "31:02" or unknown-block(31,2)
Please append a correct "root=" boot option; here are the available partitions:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(31,2)
4.无法识别文件系统
这是本来就存在的问题，后续可以解决。先记录到这里