[yocto] Running "yocto-bsp create .." in the source directory(poky) brings up an error. "poky directory vs build directory"

[Biao]

Hi all,
I am doing excises following this section
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http://www.yoctoproject.org/docs/1.7/bsp-guide/bsp-guide.html#creating-a-new-bsp-layer-using-the-yocto-bsp-script
1.6.2. Creating a new BSP Layer Using the yocto-bsp Script
...
 $ yocto-bsp create myarm qemu
....
By default, the script creates the new BSP Layer in the current working directory of the  Source Directory , which is  poky  in this case. 
....
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To my understand, it means after "source oe-init-build-env mybuild", i should change to the poky directory to run the "yocto-bsp create ..." command,
however, i got an error  
" Do you need a new machine branch for this BSP (the alternative is to re-use an existing branch)? [y/n] [default: y] 
The BBPATH variable is not set and bitbake did not find a conf/bblayers.conf file in the expected location.
Maybe you accidentally invoked bitbake from the wrong directory?
Couldn't find BBLAYERS in bitbake -e output, exiting." 
It seems it is asking me to run "yocto-bsp create ..." in the build directory


Which one is correct? Do we have a wrong document?


Thanks,
Jerry 
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