[yocto] Problems fetching branch for linux-yocto-custom

[Bryan Evenson]

> -----Original Message-----
> From: Trevor Woerner [mailto:twoerner at gmail.com]
> Sent: Wednesday, June 12, 2013 4:42 PM
> To: Bryan Evenson
> Cc: Bruce Ashfield; yocto at yoctoproject.org
> Subject: Re: [yocto] Problems fetching branch for linux-yocto-custom
> 
> On Wed, Jun 12, 2013 at 3:37 PM, Bryan Evenson
> <bevenson at melinkcorp.com> wrote:
> > # Added KBRANCH spec
> > KBRANCH = "linux-3.9-at91"
> >> > # Override SRC_URI in a bbappend file to point at a different
> >> > source
> >> #
> >> > tree if you do not want to build from Linus' tree.
> >> > SRC_URI = "git://github.com/linux4sam/linux-at91.git;branch=linux-
> >> 3.9-
> >>
> at91;tag=dcdf169e24c0cb6d7dc69e0a09d2395934e95075;protocol=git;nochec
> >> ko
> >> ut=1"
> >
> > # Changed SRC_URI to following
> > SRC_URI = "git://github.com/linux4sam/linux-
> at91.git;branch=${KBRANCH};protocol=git;nocheckout=1"
> 
> It looks like all you did was to define the string "linux-3.9-at91" in
> its own variable, put that in your SRC_URI string, and remove the
> "tag=..." field. Would your original recipe have worked if all you did
> was remove the "tag=..." field?
> 
> Is KBRANCH being used somewhere else? Doesn't bitbake's "git" fetcher
> already have a generic way of specifying a branch? Why would a kernel
> recipe need to also define a branch variable? Do non-kernel recipes
> also need to define some kind of branch variable too?

>From looking through meta/classes/kernel-yocto.bbclass, I see KBRANCH being used a lot in reference to the specific branch to be checked out.  KBRANCH_DEFAULT defines the default branch (which defaults to "master") so if you don't specify KBRANCH, then it'll checkout the KBRANCH_DEFAULT branch.

With that said, I'm wondering what would happen if I specified KBRANCH but didn't put the "branch=${KBRANCH}" in the SRC_URI.  Is this branch= variable from the SRC_URI being used for the kernel?

-Bryan