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SD card not recognized by ubuntu(armhf)/xfce

Former Member

Hi community,
i copied the ubuntu file system and boot files to SD card (fat32 and ext4 partition), similar to http://www.wiki.xilinx.com/Ubuntu+on+Zynq, (but without initramfs).

Now i would like to modify the files on the fat32 partition, but the mmcblk0p1 (and 2) do not show up in /dev.

dmesg | grep mmc
mmc0: no vmmc regulator found
mmc0: invalid maximum block size, assuming 512 bytes
mmc0: SDHCI controller on e0100000.sdhci[...] using ADMA
mmc0: new high speed SDXC card at address aaaa
mmcblk0: mmc0:aaaa SU64G 59.4 GiB
mmcblk0: p1 p2
EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)

the output is the same like with other linux implementations...the only difference, mmcblk0p1 and p2 show up in /dev.

Can you tell me, what is the problem there? why is mmcblk0p1 not showing up? Are there other ways to mount the sd card?
the card also doesn't show up in df -h....

thanks in advance for every hint.

  • 0

    Hi Charles,

    I was confused by this as well as I noticed the same thing on my ZedBoard Ubuntu system.  I guess Ubuntu does not know about the SD card disk device and partitions when it first starts up and you need to give it a push in the right direction.

    First, check to see that the SDIO and MMC driver is loaded correctly by checking for the mmcblk0 device under the sysfs folders:

    ls /sys/block/mmcblk0

    If that folder is present, then you should be able to map the raw devices to the /dev folder so that the partitions can then be mounted.  On my Ubuntu build I have three raw devices that I am concerned about:

    1) mmcblk0 - The raw disk device for SD card
    2) mmcblk0p1 - The first (boot) partition is formatted with FAT32
    3) mmcblk0p2 - The second (root file system) partition is formatted with EXT4

    Now simply make some nodes on your system to point to the major and minor device numbers.  On my system, I discovered these by looking at the symlinks in the /sys/dev/block/ folder:

    ls -l /sys/dev/block/

    On my system, I see three symlinks which actually indicate the major and minor for the mmcblk devices.

    179:0 -> /../../block/mmcblk0
    179:1 -> /../../block/mmcblk0p1
    179:2 -> /../../block/mmcblk0p2

    Then I can take those major and minor numbers to create filesystem nodes for them under the /dev folder:

    sudo mknod /dev/mmcblk0 b 179 0
    sudo mknod /dev/mmcblk0p1 b 179 1
    sudo mknod /dev/mmcblk0p2 b 179 2

    Now I can use the mount command to mount /dev/mmcblk0p1 to /mnt and access the files the FAT32 partition.

    mount /dev/mmcblk0p1 /mnt

    Then I can write a test file out to the FAT32 filesystem:

    echo 'Hello Zynq' > /mnt/test.txt

    Hopefully this works similarly for you on your end.

    Regards,

    -Kevin

  • 0

    Do you know the maximum size of SD card actually supported? I think ZNYQ officially supports SDHC and that some SDXC cards have backward compatibility. So officially SDHC tops out at 32GB, but you have got a 64GB SDXC card running.

  • 0

    Hi hrebec,

    According to Section 6.3.4 of "UG585 - Zynq-7000 AP SoC Technical Reference Manual" version 1.6:

    SD Card

    SD boot supports these features:
    u2022 Boot from standard SD or SDHC cards
    u2022 FAT 16/32 file system support for storing initial image
    u2022 Up to 32GB densities

    So I think that 32GB is the maximum density that is supported.  However, as you indicated, if your SDXC card has backwards compatibility with SDHC then it will likely also work.

    I think based upon what Charles is reporting, that he is past the point of main concern with the BootROM being able to recognize the SD card.

    Hopefully Charles is able to confirm whether or not the additional nodes helped resolve his issue.

    Regards,

    -Kevin