how to test read/write to eMMC on beaglebone black board

Do you want to do raw write ?
if so, i think you can access the mmc partitions under /dev/mmc1blkX where x is partition number(i am assuming mmc1 is for eMMC).

If you want to normal write as in if you want to create file on the filesystem you can consider eMMC as if normal disc and give its path in the open/create system-call/function and file will be create on the eMMC. And then you can write to it using write system-call/function.

If you are booting bealglebone black from microSD(mmc0) then i think you can mount eMMC to some folder and then you can do write to it.

I think you should elaborate your question a bit and then it would be easy to give suggestions to you.

Hi Ankur,
Thanks for your suggestions.i think i missed some of the details,i want to test emmc read/write functionality on beagle bone black board ,from u-boot.

In u-boot, look at the fatload command to read from eMMC and the fatwrite command to write to the eMMC.
Steve K.

Hi Sangita,
Could you please refer to the following TI wiki page.
processors.wiki.ti.com/.../Linux_Core_U-Boot_User%27s_Guide