[OE-core] How to move a recipe to another directory without invalidating its sstate-cache?

[Mike Looijmans]

On 17-12-15 07:24, Mike Looijmans wrote:
> On 16-12-15 14:33, Richard Purdie wrote:
>> On Wed, 2015-12-16 at 14:18 +0100, Mike Looijmans wrote:
>>> On 16-12-15 13:35, Richard Purdie wrote:
>>>> On Wed, 2015-12-16 at 10:38 +0100, Mike Looijmans wrote:
>>>>> I renamed "recipes-some/foo/bar.bb" to "recipes
>>>>> -some/buzz/bar.bb"
>>>>>
>>>>> Rebuilding bar and its dependencies will take about 16 hours. So
>>>>> I
>>>>> don't want
>>>>> to trigger a rebuild.
>>>>>
>>>>> running "bitbake -S printdiff bar" only reveils this:
>>>>
>>>> I'm not sure I trust the output of -S printdiff, there are some
>>>> cases
>>>> it doesn't seem to "guess" right. I wish I or someone one could fix
>>>> but
>>>> but we can do its work manually. Can you try something like:
>>>>
>>>> set TMPDIR = "x"
>>>> bitbake -S bar
>>>> rename the recipe
>>>> set TMPDIR = "y"
>>>> bitbake -S bar
>>>
>>> Found out I need an extra "none" in here:
>>> bitbake -S none bar
>>
>> Sorry, yes.
>>
>>>> then
>>>>
>>>> "ls tmp-x/stamps/xxxx/bar"
>>>> "ls tmp-y/stamps/xxxx/bar"
>>>>
>>>> and see which tasks change signature. Then run:
>>>>
>>>> "bitbake-diffsigs <sig A> <sig B>"
>>>>
>>>> and see if that makes more sense?
>>>
>>> That gave the same output. Everything after "runtaskdeps" is bogus
>>> because its
>>> value changes from [blahblah, foobar] into [buzbar, blahblah] and now
>>> diffsig
>>> seems to attempt to match the "blahblah" signatures against those of
>>> "buzbar".
>>>
>>> Which sort of hints that if my new name starts with an "f" the
>>> reordering
>>> won't happen, so I'm gonna try renaming to "fbuz" now,,,
>>
>> I still suspect this might be the way the tool displays the data rather
>> than the real problem as there is some fuzziness in the data that code
>> has to work with. Bitbake just knows there are dependencies on hashes
>> X, Y, Z and it has to try and guess how to match them up. The paths are
>> included to help reduce fuzz but are only used by the analysis code,
>> not the checksum creation.
>
> No, if the sort order doesn't change, the checksum remains the same as well.
>
> So if i rename "foo" to "far" it will not rebuild the package (using plain
> bitbake without -S switches), but if I rename "foo" to "buz" it will rebuild
> because there's a dependent package that sorts before "far" but after "buz".
>
>
>> Did the hashes themselves change or just the paths? I'm wondering if
>> the order that bitbake adds the checksums to the main checksum may have
>> some bearing on this...
>>
>> Being able to see some real data would also help. Does this reproduce
>> with a public recipe I can see the real data for?
>
> There should be quite a few recipes in OE-core that might match this pattern:
>
> Recipe X must depend on recipe Y. The directory of Y sorts before that of X.
> Renaming the directory of X to something that sorts before that of Y should
> trigger the problem.
>
> I'll see if I can locate an existing one.

Found several candidates, but couldn't get them to trigger this... Must be 
something more involved than just renaming the directory...



Kind regards,

Mike Looijmans
System Expert

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