MultiMediaCard
Instructions to use the MultiMediaCard (MMC/SD) on your Armadeus board
Contents
Introduction
You can use standard MMC/SD cards with your Armadeus board, if you have the corresponding connector attached to your development board.
Installation (obsolete now because driver is included in default Armadeus kernel)
When you build your kernel image, then modify its configuration:
[armadeus]$ make linux-menuconfig
in Device Drivers->MMC/SD Card support->iMX Support In FileSystems, don't forget to add support for the filesystem you want to use on the MMC and if you activate FAT/VFAT, don't forget to activate Native Language Support (NLS) otherwise you'll get errors like:
Unable to load NLS charset cp437 FAT: codepage cp437 not found
Save your configuration and then rebuild your kernel image:
[armadeus]$ make linux
now you should have following drivers in your kernel source tree:
drivers/mmc/
Copy mmc_core.ko, imxmmc.ko & mmc_block.ko to your target root filessytem in /lib/modules/ or reflash the generated rootfs.
If not already existing then create the MMC block devices:
# mknod /dev/mmcblk0 b 254 0 # mknod /dev/mmcblk0p1 b 254 1
If not already existing then create the mount point (/mnt/mmc):
# mkdir -p /mnt/mmc
Usage
Just mount the MMC like you will do on your PC, for example (FAT32 formatted card):
# mount -t vfat /dev/mmcblk0p1 /mnt/mmc
You can then access the MMC's files from /mnt/mmc directory
The MMC driver is now included inside the Linux kernel (no more a module) but if you want to use it as a module you will have to:
# modprobe imxmmc # modprobe mmc_block
Booting from MMC/SD
When your rootfs is too big to be put on the APF9328 FLASH, you can always use a MMC/SD like a Hard Drive and boot from it. To do that you must have MMC drivers compiled as builtin in your Linux kernel (Done by default in standard Armadeus kernel)
- Mount your MMC/SD on your Host filesystem, for example in /mnt/sdcard/
- Then put your rootfs on this MMC/SD: in Buildroot configure rootfs to be tar-ed:
[armadeus] $ make menuconfig Target Options ---> tar the root filesystem [armadeus] $ make
and then:
# tar xvf /.../armadeus/buildroot/rootfs.arm_nofpu.tar -C /mnt/sdcard/ # umount /mnt/sdcard/
- in U-Boot then use (with MMC inserted):
BIOS> run mmcboot