Re: mounting mmc device linux 2.6.12

[Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>]

On Tue, Jul 26, 2005 at 12:08:01PM +0200, Dupas.External@xxxxxxxxxxxx wrote:
> hello,
> I'm running linux 2.6.12 patched with the patch from arm site (with cramfs from arm site too).
> I'd like to mount the mmc device: 
> mount -t vfat -n /dev/mmc /tmp/mmc
> I get the following error message
> mount: /dev/mmc is not a valid block device.
> when I get a more of /proc/devices -> 
> block devices :
>  254 mmc 
> and when ls -l /dev mmc is associated to number 28 as a major number:
> brw-r--r--    1 root     root   28, 0 Jan 1 00:00 mmc

Whoever gave you this root filesystem was obviously on some kind of
drugs.  Your /dev/mmc device node is using major 28 minor 0.  However,
this major/minor number is allocated as:

 28 block       Fourth Matsushita (Panasonic/SoundBlaster) CD-ROM
                  0 = /dev/sbpcd12      Panasonic CD-ROM controller 3 unit 0
                  1 = /dev/sbpcd13      Panasonic CD-ROM controller 3 unit 1
                  2 = /dev/sbpcd14      Panasonic CD-ROM controller 3 unit 2
                  3 = /dev/sbpcd15      Panasonic CD-ROM controller 3 unit 3

or on Atari machines:

 28 block       ACSI disk (68k/Atari)
                  0 = /dev/ada          First ACSI disk whole disk
                 16 = /dev/adb          Second ACSI disk whole disk
                 32 = /dev/adc          Third ACSI disk whole disk
                    ...
                240 = /dev/adp          16th ACSI disk whole disk
                                                                                
                Partitions are handled in the same way as for IDE
                disks (see major number 3) except that the limit on
                partitions is 15, like SCSI.

Neither of them are MMC cards.  In addition, MMC cards are partitioned
devices, so they are like hard drives.  It's supposed to be:

Major	Minor
-	0	/dev/mmcblk0		first mmc card
-	1	/dev/mmcblk0p1		first mmc card first partition
-	2	/dev/mmcblk0p2		first mmc card second partition
-	3	/dev/mmcblk0p3		first mmc card third partition
	...
-	7	/dev/mmcblk0p7		first mmc card seventh partition
-	8	/dev/mmcblk1		second mmc card
	...

where '-' is the major number allocated to mmc, which by default is
dynamically allocated (which will normally be 254), or alternatively
you can use:

	insmod mmc_block major=<whatever>

to fix it to a particular major number.

Whatever, since most mmc cards are partitioned, you probably don't want
to try mounting /dev/mmcblk0, but /dev/mmcblk0p1

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