[yocto] Unable to modify patch files in u-boot recipe - quilt applies direct from layer files

[Paul Eggleton]

On Thursday 05 November 2015 11:25:18 Chris Hallinan wrote:
> On Thu, Nov 5, 2015 at 4:25 AM, Paul Eggleton
> 
> <paul.eggleton at linux.intel.com> wrote:
> > On Wednesday 04 November 2015 17:16:32 Khem Raj wrote:
> >> > On Nov 4, 2015, at 11:57 AM, Chris Hallinan <challinan at gmail.com>
> >> > wrote:
> >> > I was trying to "patch a patch" in a u-boot recipe using standard
> >> > bbappends technique.  I added a task before do_patch after do_unpack
> >> > to munge the patch that was broken.  Here is what seems to happen:
> >> > 
> >> > do_unpack:
> >> >    copies all the patch files from the metadata layer into ${WORKDIR}
> >> > 
> >> > do_fix_patch (my additional task)
> >> > 
> >> >    uses sed or patch to apply a local fix to a broken patch in
> >> >    ${WORKDIR}
> >> > 
> >> > do_patch
> >> > 
> >> >    creates a subdirectory in ${S} called "patches", and puts links to
> >> > 
> >> > the actual files in the layer and uses those links back to the layer
> >> > files to apply the patches.
> >> > 
> >> > It seems quilt is using the actual layer files instead of the ones in
> >> > ${WORKDIR}??
> >> > 
> >> > This seems odd and somehow wrong.  We copy the layer files into
> >> > WORKDIR, and the unsuspecting user (me) thinks those are the files
> >> > that do_patch will use.
> >> > 
> >> > This one took me some time (and help) to figure out!
> >> > 
> >> > Comments?  Is this a bug?  halfway in the middle of some architectural
> >> > changes?  Expected behavior?
> >> 
> >> while what you are doing is quite questionable. You seem to have a point.
> >> Most probably copy of the files in workdir should be removed from
> >> happening.
> >> 
> >> > My workaround was to simply replace the entire patch.
> >> 
> >> you should use the quilt workflow and edit/refresh the patch once and
> >> copy
> >> it back to metadata once for all yes.
> > 
> > Or devtool modify, change the patch in the resulting git repository, then
> > devtool update-recipe -a.
> 
> Thanks for comments.  But the point here is that in some workflows
> (especially with a commercial vendor's implementation) we strongly
> encourage users _NOT_ to modify the distributed sources, but to make
> all modifications in users layers.  This provides a more manageable
> upgrade path.  I guess the strangeness is that files from
> recipe/metadata are copied to WORKDIR, but are not used, and I found
> that very confusing at first.  Lesson learned! ;)

Right, that's what the -a does though - puts your change into a bbappend as 
opposed to the original recipe.

> I guess I find it a bit strange that quilt (I assume it's quilt) links
> back to the layer/metadata files directly and not back to the files in
> WORKDIR, which seems more reasonable and easier to modify.  I could
> label this as a "bug" rather than a "feature".  Matter of perspective,
> perhaps.

Yeah, I think it would be reasonable to fix this as well. I have sometimes 
wondered myself why the symlinking was done this way.

Going forward though I would like to encourage people to use devtool modify 
for this kind of thing rather than working with files in the WORKDIR, because 
among other things there's less chance of losing work when WORKDIR goes away. 
If that means we need to enhance or fix devtool so it works better for people 
then by all means let's do that.

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre