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

[Bruce Ashfield]

On 13-06-12 4:54 PM, Bryan Evenson wrote:
>
>
>> -----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?
>

There are compatibility checks that will pick up branch, and set
KBRANCH on your behalf if you only use branch= in the SRC_URI, but
there are limitations since clobbering a KBRANCH variable isn't
always possible due to when they are expanded (i.e. recipe parse
time).

Cheers,

Bruce

> -Bryan
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