[U-Boot] RW access to MMC/SD devices

[twebb]

Does u-boot support Write access to MMC/SD devices?  I know it supports
reading because the version I have from OMAP 35x SDK allows booting
the linux kernal from MMC/SD card.  From previous thread I
believe the answer is no for writing in a filesystem's format
(i.e. fat32 or ext3 for example).  Is there a method to do "raw"
writes?

(This is essentially a repost from a few weeks ago - I never got any
response so am trying again.)

Thanks,
twebb