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

[Khem Raj]

On Thu, Nov 5, 2015 at 9:05 AM, Paul Eggleton
<paul.eggleton at linux.intel.com> wrote:
> 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.

its time/space optimization more than anything you avoid copying and copies

>
> 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