Find specific changes between revisions

[Daniel Ebdrup Jensen]

On Sun, May 10, 2020 at 10:41:24PM +0700, Eugene Grosbein wrote:
>10.05.2020 5:52, Mario Lobo wrote:
>
>> The command:
>>
>> svn diff https://svn.freebsd.org/base/stable/11@359971
>> https://svn.freebsd.org/base/stable/11@360676
>>
>> yielded a 170 Mbytes file!!
>>
>> It will be like looking for a needle in a haystack, in the dark, with just
>> a hunch of where the needle was dropped.
>>
>> Well ... at least I have the haystack.
>>
>> Thanks everyone for the tips!
>
>You don't really need to study source code to bisect the problem,
>just use "svnlite update -rZZZZZ" to move your source tree to the middle point
>between known working and non-working revisions. Then rebuild and reinstall
>kernel and world, reboot and re-do the test. If it works, you get new (higher)
>working revision and if not, you get new (lower) non-working one.
>
>Repeat until you have only single revision between working and non-working.
>This procedure takes time and effort but this is not like looking for a needle in a haystack, much easier.
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If you're going to be doing this kind of rebuilding from revision to revision, I 
feel obliged to mention that you can put MetaMode [1] to great use.

Essentially, it ensures that you only rebuild whatever's changed from one 
revision to another, and on the source tree it can make a HUGE difference when 
jumping small revision amounts (and even if large numbers of revisions are 
jumped over, it still has some impact.
It's sort of like ccache, except much more efficient.

Yours,
Daniel Ebdrup Jensen

[1]: https://wiki.freebsd.org/MetaMode
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