問題現象描述：
以NFS方式掛載文件時打印錯誤信息：
IP-Config: Guessing netmask 255.255.255.0
IP-Config: Complete:
device=eth0, addr=192.168.1.221, mask=255.255.255.0, gw=255.255.255.255,
host=192.168.1.221, domain=, nis-domain=(none),
bootserver=255.255.255.0, rootserver=192.168.1.130, rootpath=
Looking up port of RPC 100003/2 on 192.168.1.130
eth0: link up (100/Full)
rpcbind: server 192.168.1.130 not responding, timed out
Root-NFS: Unable to get nfsd port number from server, using default
Looking up port of RPC 100005/1 on 192.168.1.130
rpcbind: server 192.168.1.130 not responding, timed out
Root-NFS: Unable to get mountd port number from server, using default
Root-NFS: Server returned error -5 while mounting /home/dah/rfs-1.16-432
VFS: Unable to mount root fs via NFS, trying floppy.
List of all partitions:
No filesystem could mount root, tried: nfs
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)
[<c002930c>] (unwind_backtrace+0x0/0xdc) from [<c0232ea8>] (panic+0x40/0x110)
[<c0232ea8>] (panic+0x40/0x110) from [<c0008fec>] (mount_block_root+0x1d0/0x210)
[<c0008fec>] (mount_block_root+0x1d0/0x210) from [<c0009284>] (prepare_namespace+0x164/0x1bc)
[<c0009284>] (prepare_namespace+0x164/0x1bc) from [<c000859c>] (kernel_init+0xb8/0xe4)
[<c000859c>] (kernel_init+0xb8/0xe4) from [<c003ce20>] (do_exit+0x0/0x5ac)
[<c003ce20>] (do_exit+0x0/0x5ac) from [<ffffffff>] (0xffffffff)
開始一直以爲是內核的配置問題。
最開始懷疑.1.130的NFS服務沒啓動，再懷疑PORTMAP沒有啓動。重啓兩服務後，現象依舊。
後面找到一塊9260的開發板，它是RMII方式的，將UBOOT，KERNEL燒進開發板，正常。後面就懷疑是硬件的問題。對比了一下原理圖，硬件無錯。鬱悶了N個小時ing...
用TFTP方式上傳數據內核，跳到內核運行，相當正常。說明UBOOT初始化沒有問題。那麼有問題的只可能是內核了。
後面看源碼發現，AT91SAM9260部分，發現linux-2.6.30/arch/arm/mach-at91/at91sam9260_devices.c文件中有這麼些東東：
/* --------------------------------------------------------------------
* Ethernet
* -------------------------------------------------------------------- */
#if defined(CONFIG_MACB) || defined(CONFIG_MACB_MODULE)
static u64 eth_dmamask = DMA_BIT_MASK(32);
static struct at91_eth_data eth_data;
static struct resource eth_resources[] = {
[0] = {
.start = AT91SAM9260_BASE_EMAC,
.end = AT91SAM9260_BASE_EMAC + SZ_16K - 1,
.flags = IORESOURCE_MEM,
},
[1] = {
.start = AT91SAM9260_ID_EMAC,
.end = AT91SAM9260_ID_EMAC,
.flags = IORESOURCE_IRQ,
},
};
static struct platform_device at91sam9260_eth_device = {
.name = "macb",
.id = -1,
.dev = {
.dma_mask = ð_dmamask,
.coherent_dma_mask = DMA_BIT_MASK(32),
.platform_data = ð_data,
},
.resource = eth_resources,
.num_resources = ARRAY_SIZE(eth_resources),
};
void __init at91_add_device_eth(struct at91_eth_data *data)
{
if (!data)
return;
if (data->phy_irq_pin) {
at91_set_gpio_input(data->phy_irq_pin, 0);
at91_set_deglitch(data->phy_irq_pin, 1);
}
printk("********data->phy_irq_pin = %d./n",data->phy_irq_pin);
/* Pins used for MII and RMII */
at91_set_A_periph(AT91_PIN_PA19, 0); /* ETXCK_EREFCK */
at91_set_A_periph(AT91_PIN_PA17, 0); /* ERXDV */
at91_set_A_periph(AT91_PIN_PA14, 0); /* ERX0 */
at91_set_A_periph(AT91_PIN_PA15, 0); /* ERX1 */
at91_set_A_periph(AT91_PIN_PA18, 0); /* ERXER */
at91_set_A_periph(AT91_PIN_PA16, 0); /* ETXEN */
at91_set_A_periph(AT91_PIN_PA12, 0); /* ETX0 */
at91_set_A_periph(AT91_PIN_PA13, 0); /* ETX1 */
at91_set_A_periph(AT91_PIN_PA21, 0); /* EMDIO */
at91_set_A_periph(AT91_PIN_PA20, 0); /* EMDC */
if (!data->is_rmii) {
at91_set_B_periph(AT91_PIN_PA28, 0); /* ECRS */
at91_set_B_periph(AT91_PIN_PA29, 0); /* ECOL */
at91_set_B_periph(AT91_PIN_PA25, 0); /* ERX2 */
at91_set_B_periph(AT91_PIN_PA26, 0); /* ERX3 */
at91_set_B_periph(AT91_PIN_PA27, 0); /* ERXCK */
at91_set_B_periph(AT91_PIN_PA23, 0); /* ETX2 */
at91_set_B_periph(AT91_PIN_PA24, 0); /* ETX3 */
at91_set_B_periph(AT91_PIN_PA22, 0); /* ETXER */
printk("********eth0 is MII mode./n");
}
eth_data = *data;
platform_device_register(&at91sam9260_eth_device);
}
#else
void __init at91_add_device_eth(struct at91_eth_data *data) {}
#endif
我在上述函數中加了兩條打印信息，發現只打印一條：data->phy_irq_pin = 39。這說明data->is_rmii=1。說明內核默認是支持RMII的。其傳遞的參數是：is_rmii;該參數在linux-2.6.30/arch/arm/mach-at91/board-sam9260.c 中設置。我順便將irq_phy_pin更改爲：AT91_PIN_PC12。
重新編譯，一切搞定！！！喝杯茶，休息一下...