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Where is the MMC/SD mapped on L137 EVM?

Sean50453
Intellectual 940 points

Hi, does anybody know where is the MMC/SD mapped by default on the L137 EVM board?  I thought it's mapped in Linux as /dev/sda, but couldn't locate this folder.  Thanks.

  • 0
    Guru 26430 points

    Maybe /dev/mmcblk0p1.

  • 0 in reply to Norman Wong
    Intellectual 940 points

    Norman, I found mmcblk0p1 under the /dev folder.  Right now my kernel setting is :

    bootargs=      mem=32M console=ttyS2,115200n8 root=/dev/mmcblk0p1 noinitrd rw ip=none

    Does it mean that, once kernel starts, it will jump to /dev and run the mmcblk0p1 file?  Is it .exe or .bin file? 

    Do you know where to find an instruction on how to compile an application code on MMC/SD in Win7 for MV Linux embedded system?

    Thanks,

    - Sean

  • 0 in reply to Sean50453
    Guru 26430 points

    Specifying "root=/dev/mmcblk0p1" means the kernel expects a linux file system there. That means it will have all the usual Linux directories like "dev', "bin", lib", etc. The EVM should have come with a EXT2 formatted SD Card with a linux file system. I think that one of the MontaVista DVDs that came with the EVM has the entire toolchain as well as a file system image in tarball and tree form for NFS. That said, I'd recommend thinking about switching to the Arago toolchain and kernel.

    It's easiest to have a real Linux machine for a host. Using Windows(Cygwin) for a development host rarely works. Try looking at processors.wiki.ti.com.

  • 0 in reply to Norman Wong
    Intellectual 940 points

    I remember you mentioned before using windows (Cygwin) as the host rarely works.  Is that due to compiling issues?  If I'm using ubuntu with WMplayer and compiling FS in ubuntu, will it work?  I looked at the processor wiki and it seems like I can mount the MMC/SD (through a card reader?) to the OS.

    http://processors.wiki.ti.com/index.php/Creating_filesystems_on_removable_media#MontaVista_Linux_based_SDK

    I'm not using NFS, instead I want to compile the FS in host and download to MMC/SD directly.  Is there MMC/SD writing utility and examples (e.g. Ethernet, gpio, etc) that I can use to learn the use of MMMC/SD under MVLinux on L137 EVM?  I don't think copy/paste a compiled FS to MMC/SD would work.  Thanks.

  • 0 in reply to Sean50453
    Guru 26430 points

    The build systems depend a lot of utilities that only run properly under Linux. It is not just the cross compiler. Linux under a VM is certainly "real". The Angstrom version of Linux is based upon using Ubuntu VMs for hosts. You should be able to format, mount and populate the SD Card in a Ubuntu VM. I usually just use a pre-built file system. Building a file system from scratch as a lot of work. Some use builds systems like bitbake or buildroot to build the file system from scratch.

    Personally, I haven't much success with just copying an existing compiled file system to an SD Card. I usually have to use tar to properly create a file system on an SD Card. The tar commands appears to properly handle the special files and permissions required. But that Wiki page does use "cp". Give it try. Maybe I was doing it wrong.

    I don't quite understand what you mean by MMC/SD writing utitlity and examples.