[Buildroot] [RFC] [PATCH v2 2/2] support/kconfig: Bump to kconfig from Linux 4.17-rc2

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello,

On Tue, 31 Jul 2018 09:55:42 +0200, Arnout Vandecappelle wrote:

> >>> We're only talking about dropping the need for host-flex and host-bison
> >>> for the kconfig stuff. In this case, we don;t care that the user
> >>> generates C code one way or another: it's only a host tool...    
> >>
> >>  I was replying to Thomas's "we should remove host-flex and host-bison
> >> entirely". Yes we can rely on system-installed flex and bison for kconfig, but
> >> we can't rely on that for target packages, e.g. target dtc.  
> > 
> > Why so ?  
> 
>  Reproducibility. I tested this for something (I think it was flex, but as usual
> I don't remember exactly), and the code generated by my system's flex was wildly
> different from what was generated by Buildroot's host-flex, even though the
> versions were pretty close. Unfortunately, I don't remember exactly, but that
> was my concern.

True, but then if we have this reproducibility issue, it also applies
to building the kconfig code, no ?

Or do you assume that because kconfig is so widely used, it is tested
against lots of bison/flex version, so we don't need to build
bison/flex for kconfig, but we should still build it for other packages
that need bison/flex, as those ones may be less tested against random
versions of flex/bison ? Or because the generated flex/bison code goes
into the target, and we ideally want binary-identical results for a
given Buildroot configuration ?

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com