[yocto] tar ball vs. git development questions

[jfabernathy]

On 01/22/2012 08:12 PM, Gary Thomas wrote:
> On 2012-01-22 13:19, James Abernathy wrote:
>> I have used both git and the tarball methods of bitbaking projects, 
>> all of them derivatives of the examples in the Yocto documentation. I 
>> was having issues using the local clone of
>> the Yocto kernel git repository this weekend. I had successfully done 
>> that before, but I was rebuilding the PC workstation, and getting 
>> everything setup and tested some of the
>> meta-intel BSPs to make sure I had everything right. Cloning the 
>> linux-yocto-3.0 repository was successful, but the bakes against it 
>> failed. I made sure I had poky-extras setup
>> right, but I still had problems. To isolate the problem, I changed to 
>> building with the tarballs and everything worked fine.
>>
>> So that got me thinking what are the differences between the 2 methods:
>>
>>   * I assume that if I use the tarball method, bitbake, using the 
>> recipes, pulls down files from the online repositories and puts those 
>> files into the centralized local download
>>     directory ($DL_DIR), allowing reuse instead of re-downloading 
>> each time. The content downloaded for linux-yocto-3.0 is exactly what 
>> would be pulled from the local repository if
>>     I used a local clone of the git repository for linux-yocto-3.0.
>>   * If my assumption above is correct, if I'm not modifying the 
>> source code of the kernel (only changing config parameters), then 
>> once you've run at least one build with the
>>     tarball method, the $DL_DIR directory contains all the files 
>> you'll need to build any image with linux-yocto-3.0. So there is no 
>> need to have a local clone of the kernel
>>     repository for speeding up development. Am I right?
>>   * If I have a successful creation of a bare clone of 
>> linux-yocto-3.0.git, how could builds of Edison packages be failing? 
>> That makes me concerned about using git and successfully
>>     repeating builds of stable branches like Edison.
>
> If you set BB_GENERATE_MIRROR_TARBALLS = "1" (e.g. in local.conf)
> then you'll get tarballs which hold the git repositories after
> download.  You can then reuse these (by sharing the DL_DIR or
> using a local mirror).  Does that help with the issue you're seeing?
>
I'm not sure it does.  I don't want poky to do more work.  I have my 
download directory, $DL_DIR, outside my build directory so I can keep it 
run to run, as mentioned in the comments in local.conf. I was trying to 
understand 2 basic questions:

1.  what could be causing build failures using a freshly created bare 
clone yesterday vs. using the poky-edison-6.0 tarball.  It would be 
scary if you could clone the linux-yocto-3.0 successfully one day and 
have it be used in a build successfully, but clone it another day and it 
not work.  I figured that bitbake/poky pulled the same information into 
DL_DIR regardless of whether you pulled from the bare clone locally or 
straight from the on-line repository.
2. I was trying to look at items to speed up build runs.  I thought that 
if the downloads in DL_DIR were reused if they existed, it would speed 
up a run. It seems to.  So the question is, after the first build, the 
files I need for linux-yocto-3.0 are in DL_DIR regardless of whether 
they came from the online repository or the local bare clone. right?

Jim A