Messages in this thread | | | Subject | Re: [PATCH 0/2] do not select KALLSYMS_ALL | From | Artem Bityutskiy <> | Date | Fri, 01 Apr 2011 17:40:33 +0300 |
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On Thu, 2011-03-31 at 15:18 +0100, Paulo Marques wrote: > Artem Bityutskiy wrote: > > [...] > > I personally think KALLSYMS_ALL should be just merged with KALLSYMS and > > disappear - we should have only one option. CONFIG_KALLSYMS_EXTRA_PASS should > > die as well. > > That sounds a little too extreme... > > KALLSYMS is useful for most kernels, since it provides nice readable > stack dumps for panics and BUG's. > > KALLSYMS_ALL adds a lot of extra symbols that can be useful mostly to > development kernels and shouldn't be used to add unnecessary bloat to > user kernels.
OK, thanks.
> Now as for CONFIG_KALLSYMS_EXTRA_PASS: to build the kallsyms table, the > build process first links a kernel image with an empty kallsyms table > and use that to fetch information for all the symbols. > > It then uses that information to build the table with the right size, > and links it again. If everything goes ok, this new version as all the > symbols in the correct places and the final table can be built with the > correct addresses. > > The final linking should produce the same result as only the data on the > kallsyms table changed, but not its size. > > However, there have been bugs in the past with section alignments and > symbol reordering for symbols with the same address, etc., etc. that > make this final table not have the exact same size, and the build fails > with an inconsistent kallsyms data message. At this point, the user can > turn on the CONFIG_KALLSYMS_EXTRA_PASS and temporarily solve the problem > while the developers find the correct fix. Without this option, in this > situation the kernel would simply fail the compilation. > > All this has been stable for a while and this option hasn't been needed > recently (AFAIK), but if there is some bug in some new binutils or > something, the option might be needed again.
Thanks for explanation!
But... why on earth this option is in Kconfig then, if this is only about extra pass during the kernel _compilation_ ? This and the vague help message in Kconfig help section are very misleading. This should not be in Kconfig at all then, it should be purely a Makefile thing!
-- Best Regards, Artem Bityutskiy (Артём Битюцкий)
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