板子上挂载SD卡时：
umount: /mnt/mmc: not mounted
mount: /dev/mmcblk0 is not a valid block device
mount: /dev/mmcblk0p1 is not a valid block device
cat /proc/partitions
major minor #blocks name
31 0 3072 mtdblock0
31 1 2048 mtdblock1
31 2 4096 mtdblock2
31 3 24576 mtdblock3
31 4 2048 mtdblock4
31 5 95232 mtdblock5
cat /proc/devices
Character devices:
1 mem
4 /dev/vc/0
4 tty
4 ttyS
5 /dev/tty
5 /dev/console
5 /dev/ptmx
7 vcs
10 misc
13 input
14 sound
21 sg
81 video4linux
89 i2c
90 mtd
108 ppp
116 alsa
128 ptm
136 pts
180 usb
189 usb_device
247 cmem
248 dm365mmap
249 irqk
250 edma
251 dev_dma
252 dev_i2c
253 csl
254 rtc
Block devices:
1 ramdisk
7 loop
8 sd
31 mtdblock
65 sd
66 sd
67 sd
68 sd
69 sd
70 sd
71 sd
128 sd
129 sd
130 sd
131 sd
132 sd
133 sd
134 sd
135 sd
253 mmc
ls -l /dev/mmc*
brwxrwxrwx 1 root root 253, 0 Nov 11 2011 /dev/mmcblk0
brwxrwxrwx 1 root root 253, 1 Nov 11 2011 /dev/mmcblk0p1
请问这是什么原因，怎么解决啊？菜鸟求救！！！
