linux-kernel - Re: [PATCH v6 01/24] x86/mm: Define CONFIG

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Date:   Mon, 15 Jan 2018 18:49:17 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Laurent Dufour <ldufour@...ux.vnet.ibm.com>
cc:     paulmck@...ux.vnet.ibm.com, peterz@...radead.org,
        akpm@...ux-foundation.org, kirill@...temov.name,
        ak@...ux.intel.com, mhocko@...nel.org, dave@...olabs.net,
        jack@...e.cz, Matthew Wilcox <willy@...radead.org>,
        benh@...nel.crashing.org, mpe@...erman.id.au, paulus@...ba.org,
        Ingo Molnar <mingo@...hat.com>, hpa@...or.com,
        Will Deacon <will.deacon@....com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        kemi.wang@...el.com, sergey.senozhatsky.work@...il.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        haren@...ux.vnet.ibm.com, khandual@...ux.vnet.ibm.com,
        npiggin@...il.com, bsingharora@...il.com,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: Re: [PATCH v6 01/24] x86/mm: Define CONFIG_SPF

On Mon, 15 Jan 2018, Laurent Dufour wrote:
> On 12/01/2018 19:57, Thomas Gleixner wrote:
> > On Fri, 12 Jan 2018, Laurent Dufour wrote:
> > 
> >> Introduce CONFIG_SPF which turns on the Speculative Page Fault handler when
> >> building for 64bits with SMP.
> >>
> >> Signed-off-by: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
> >> ---
> >>  arch/x86/Kconfig | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >>
> >> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> >> index a317d5594b6a..d74353b85aaf 100644
> >> --- a/arch/x86/Kconfig
> >> +++ b/arch/x86/Kconfig
> >> @@ -2882,6 +2882,10 @@ config X86_DMA_REMAP
> >>  config HAVE_GENERIC_GUP
> >>  	def_bool y
> >>  
> >> +config SPF
> >> +	def_bool y
> >> +	depends on X86_64 && SMP
> > 
> > Can you please put that into a generic place as
> > 
> >     config SPF
> >     	   bool
> > 
> > and let the architectures select it.
> 
> I'll change that to let the architectures (x86 and ppc64 currently)
> selecting it, but the definition will remain in the arch/xxx/Kconfig file
> since it depends on the architecture support in the page fault handler.

Errm. No.

	config SPECULATIVE_PAGE_FAULT
      		bool

goes into a generic config file, e.g. mm/Kconfig

Each architecture which implements support does:

	select SPECULATIVE_PAGE_FAULT

in arch/xxx/Kconfig

Thanks,

	tglx