Kernel compile times

[Jebbe9]

Should it be that way that when you recompile a new kernel it takes bit longer than when you for instance have already compiled the same version kernel a couple of times?

[NeddySeagoon]

Jebbe9,

Yes, that's correct.

make is lazy. It looks at the timestamp on an output file then on the timestamps of all the input files that contribute to the output fiile.
If the output file is newer than the input files, it has not changed, so make does nothing.
It still has to visit every node to know that there is nothing to do.

With a new kernel, there are no output files to reuse, so they all have to be created.
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Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

[Jebbe9]

Alright, that clears things up a bit. Thanks.

[Buffoon]

You can "fix" it with 'make clean'.
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[Ant P.]

You can also maintain a git kernel tree outside of portage and it won't rebuild everything even between major releases, but that can cause problems if you don't keep it maintained.

ccache is also an option and probably safer.

[Jebbe9]

[pietinger]