Re: [PATCH 05/10] tools headers: Synchoronize x86 features UAPI headers

[Ingo Molnar]

* David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:

> 
> 
> On Mon, 2018-02-05 at 16:56 -0300, Arnaldo Carvalho de Melo wrote:
> > 
> > None will entail changes in the tools/perf/, synchronizing to elliminate
> > these perf build warnings:
> > 
> > Â Warning: Kernel ABI header at 'tools/arch/x86/include/asm/disabled-features.h' differs from latest version at 'arch/x86/include/asm/disabled-features.h'
> > Â Warning: Kernel ABI header at 'tools/arch/x86/include/asm/required-features.h' differs from latest version at 'arch/x86/include/asm/required-features.h'
> > Â Warning: Kernel ABI header at 'tools/arch/x86/include/asm/cpufeatures.h' differs from latest version at 'arch/x86/include/asm/cpufeatures.h'
> 
> Ick. Have we considered just using a symlink? Why have copies of the
> same header file in different places in the tree, and tooling to
> complain iÌfÌwhen they get out of sync?

In the past we had incidents where kernel changes broke tooling and vice versa.

This is basically a soft-COW mechanism that decouples tooling source code from the 
kernel source code, while still having a technological mechanism in place that 
encourages the syncing of header files.

Thanks,

	Ingo