Tech memo of imx27 pdk(3) -- For network and rootfs mounting problems

At the end of Tech memo of imx27 pdk(2), we saw the kernel hang-up after trying to bring up eth0. I would introduce some hardware knowledge before fixing this issue.

imx27 pdk has two ne2k cark, they are

lan8700, which is soldered to core board, and

lan9217, which is soldered to debug board.

The first one is configure to eth0 while the rest one is configure to eth1. Though they are both from SMSC but they have different dirvers in kernel. The driver of lan8700, so far as i know, is in drivers/net/fec.c, which is somehow created by Motorola while the driver of lan9217 is in drivers/net/smsc911x.c. If you are interested you can study their driver to see how the ne2k chip works.

Ok let's go back to the issue. My finding is, in my redboot booting scripts, i didn't assign MAC address to the net card i want to bring up.

So i changed the script to this:

exec -b 0x100000 -l 0x200000 -c "console=ttymxc0,115200 root=/dev/nfs nfsroot=192.168.10.212:/home/hongao_client/ltib/rootfs_fr_jffs2_img init=/linuxrc ip=192.168.10.119:192.168.10.1:192.168.10.1:255.255.255.0 fec_mac=00:04:9F:00:D4:8F"

and If you dun want to use DHCP, you can change the code like below:

(net/ipv4/ipconfig.c)

static int __init ip_auto_config(void)

{

... ...

 printk(KERN_INFO "[HONGAO DBG]%s:%d/n", __FUNCTION__, __LINE__);

 ic_dev = ic_first_dev->dev;

 printk("/n      device=%s", ic_dev->name);

 printk(", addr=%u.%u.%u.%u", NIPQUAD(ic_myaddr));

 printk(", mask=%u.%u.%u.%u", NIPQUAD(ic_netmask));

 printk(", gw=%u.%u.%u.%u", NIPQUAD(ic_gateway));

 printk(",/n     host=%s, domain=%s, nis-domain=%s",

        utsname()->nodename, ic_domain, utsname()->domainname);

 printk(",/n     bootserver=%u.%u.%u.%u", NIPQUAD(ic_servaddr));

 printk(", rootserver=%u.%u.%u.%u", NIPQUAD(root_server_addr));

 printk(", rootpath=%s", root_server_path);

 printk("/n");

 if (ic_myaddr == NONE ||

#ifdef CONFIG_ROOT_NFS

     (MAJOR(ROOT_DEV) == UNNAMED_MAJOR

      && root_server_addr == NONE

      && ic_servaddr == NONE)// ||

#endif

     ) {

#ifdef IPCONFIG_DYNAMIC

... ...

}

And we better write a script for building code:

/home/hongao_client/ltib/hongao.sh:

#!/bin/bash

cd /home/hongao_client/ltib/rpm/BUILD/linux-2.6.22/

make ARCH=arm CROSS_COMPILE=/opt/freescale/usr/local/gcc-4.1.2-glibc-2.5-nptl-3/arm-none-linux-gnueabi/bin/arm-none-linux-gnueabi-

cd /home/hongao_client/ltib/

./ltib -p kernel -m scinstall

Ok then reboot, you will see:

[HONGAO DBG]fec_enet_open:2732 config:dev name=eth0

[HONGAO DBG]fec_set_mac_address:MAC=d48f880800049f00

[HONGAO DBG]fec_enet_open:2744, fep->phy=true

[HONGAO DBG] fep->phy->ack_int=0xc02f6774

[HONGAO DBG] fep->phy->config=0xc02f6734

[HONGAO DBG]mii_queue_config:2596 config:dev name=eth0

[HONGAO DBG]mii_display_config:2491

eth0: config: auto-negotiation on, 100FDX, 100HDX, 10FDX, 10HDX.

[HONGAO DBG]fec_enet_open:2763

[HONGAO DBG]fec_enet_open:2774

[HONGAO DBG]fec_enet_open:2777

eth1: SMSC911x/921x identified at 0xc885e000, IRQ: 256

eth1: SMSC911x MAC Address: 00:04:9f:00:d2:b0

eth1: link down

[HONGAO DBG]ip_auto_config:1285

      device=eth0, addr=192.168.10.119, mask=255.255.255.0, gw=192.168.10.1,

     host=(none), domain=, nis-domain=(none),

     bootserver=192.168.10.1, rootserver=192.168.10.212, rootpath=

[HONGAO DBG] ip_auto_config:1364

[HONGAO DBG] root_server_path=

IP-Config: Complete:

      device=eth0, addr=192.168.10.119, mask=255.255.255.0, gw=192.168.10.1,

     host=192.168.10.119, domain=, nis-domain=(none),

     bootserver=192.168.10.1, rootserver=192.168.10.212, rootpath=

[HONGAO DBG]do_initcalls end:711

Looking up port of RPC 100003/2 on 192.168.10.212

eth0: status: link up, 100MBit Full Duplex.

[HONGAO DBG]mii_relink:2547:linked already!!!

[HONGAO DBG]fec_set_mac_address:MAC=d48f880800049f00

Looking up port of RPC 100005/1 on 192.168.10.212

VFS: Mounted root (nfs filesystem).

Freeing init memory: 428K

[HONGAO DBG]init_post:770

[HONGAO DBG]init_post:779:exe cmd:/linuxrc

init started: BusyBox v1.6.1 () multi-call binary

starting pid 790, tty '': '/etc/rc.d/rcS'

Setting the hostname to freescale

Mounting /proc and /sys

Starting the hotplug events dispatcher udevd

Synthesizing initial hotplug events

Mounting filesystems

mount: sysfs already mounted or /sys busy

mount: according to mtab, /sys is already mounted on /sys

Starting syslogd and klogd

Let's make a rootfs folder on nfs server. A correct rootfs folder could be extracted from offical rootfs.jffs2 by the following commands:

modprobe mtdblock

rmmod mtdram

modprobe mtdram total_size=65536 erase_size=128

modprobe jffs2

dd if=ImageFile of=/dev/mtdblock0

mount /dev/mtdblock0 /home/hongao_client/ltib/rootfs_fr_jffs2_img -t jffs2

on nfs server, my setting is:

[[email protected] ltib]$ cat /etc/exports

/home/hongao_client *(rw,sync,no_root_squash)

/home/hongao_client/ltib/rootfs *(rw,sync,no_root_squash)

/home/hongao_client/ltib/rootfs_fr_jffs2_img *(rw,sync,no_root_squash)

#/home/hongao_client/utu/s3c2440_recover *(rw,sync,no_root_squash)

[[email protected] ltib]$ showmount -e

Export list for localhost.localdomain:

/home/hongao_client                          *

/home/hongao_client/ltib/rootfs              *

/home/hongao_client/ltib/rootfs_fr_jffs2_img *

Ok, Good! we can successfully enter in command line now. But LCD still has some problems. Let's fix it up in the following sessions.