Re: 2.6: spurious recompiles

[Andi Kleen]

"Randy.Dunlap" <rddunlap@xxxxxxxx> writes:

> > When doing a "make" inside an already compiled kernel source there
> > shouldn't be anything rebuilt. I've identified three places where this
> > isn't the case in recent 2.6 kernels:
> >
> > 1. ikconfig
> >   CC      kernel/configs.o
> > even when the .config wasn't changed
> 
> This is probably the same thing that Steve Hemminger posted about
> yesterday:
> http://marc.theaimsgroup.com/?l=linux-kernel&m=106270067411137&w=2
> 
> I posted a patch based on Sam Ravnborg's comments that might fix it,
> but I haven't verified it yet... The patch is in this message:
> http://marc.theaimsgroup.com/?l=linux-kernel&m=106272687506379&w=2
> 
> or it may be some other dependency.  I'll look into it.

x86-64 has the same problem. It always rebuilds arch/x86_64/ia32/vsyscall32.so,
no matter if it has changed or not. I have not figured out why it does that.

vsyscall.S is an assembly file which depends on asm/offset.h, which 
is regenerated each build. But the regeneration is written in a way to 
not trigger rebuilds when nothing has changed. That works for everything
else, just apparently not for the vsyscall.S file.

-Andi
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