Thanks Ross. The idea of more packages getting pulled in due to dependencies is going to help me. I needed many packages under recipes-devtools. So I thought it might be better to pull them all instead of listing each one of them. 
After seeing your response I realize that I will end up with 3 package managers.  So I will just chose one.
If I have to chose just one, will any one of them (say apt)  work? I somehow had come to believe that you can only use opkg in Yocto. 
thanks and best regardsMadhu



      From: "Burton, Ross" <ross.burton@intel.com>
 To: Madhu Krishnamurthy <madhukanthk@yahoo.com> 
Cc: "yocto@yoctoproject.org" <yocto@yoctoproject.org>
 Sent: Saturday, May 11, 2019 8:35 AM
 Subject: Re: [yocto] How do I include all packages under a layer ?
   
On Sat, 11 May 2019 at 00:54, Madhu Krishnamurthy <madhukanthk@yahoo.com> wrote:
> Do I have to specify every package or is there a way I can add all packages inside a layer?
> For example, how do I add all packages from inside poky/meta to my image?
> Or at least how do I add all packages under poky/meta/recipes-devtools ?

You need to list them explicitly.  Some layers have packagegroups that
pull in all the dependencies if that makes sense, but adding "all of
oe-core/recipes-devtools" would be odd: you'd have three package
managers for a start.

Ross