Re: [PATCH 05/20] arm64: rename COMPAT to AARCH32_EL0 in Kconfig

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From	Catalin Marinas <catalin.marinas@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 05/20] arm64: rename COMPAT to AARCH32_EL0 in Kconfig
Date	Fri, 09 Jun 2017 13:10:02 +0200
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On Fri, Jun 09, 2017 at 01:40:59AM +0300, Yury Norov wrote:
> On Thu, Jun 08, 2017 at 03:09:12PM +0100, Catalin Marinas wrote:
> > On Sun, Jun 04, 2017 at 02:59:54PM +0300, Yury Norov wrote:
> > > --- a/arch/arm64/Kconfig
> > > +++ b/arch/arm64/Kconfig
> > > @@ -402,7 +402,7 @@ config ARM64_ERRATUM_834220
> > >  
> > >  config ARM64_ERRATUM_845719
> > >  	bool "Cortex-A53: 845719: a load might read incorrect data"
> > > -	depends on COMPAT
> > > +	depends on AARCH32_EL0
> > >  	default y
> > >  	help
> > >  	  This option adds an alternative code sequence to work around ARM
> > > @@ -784,7 +784,7 @@ config FORCE_MAX_ZONEORDER
> > >  
> > >  menuconfig ARMV8_DEPRECATED
> > >  	bool "Emulate deprecated/obsolete ARMv8 instructions"
> > > -	depends on COMPAT
> > > +	depends on AARCH32_EL0
> > >  	help
> > >  	  Legacy software support may require certain instructions
> > >  	  that have been deprecated or obsoleted in the architecture.
> > > @@ -1062,9 +1062,15 @@ menu "Userspace binary formats"
> > >  source "fs/Kconfig.binfmt"
> > >  
> > >  config COMPAT
> > > +	bool
> > > +	depends on AARCH32_EL0
> > 
> > You could just use "def_bool y" here
> > 
> > > +
> > > +config AARCH32_EL0
> > >  	bool "Kernel support for 32-bit EL0"
> > > +	def_bool y
> > >  	depends on ARM64_4K_PAGES || EXPERT
> > >  	select COMPAT_BINFMT_ELF if BINFMT_ELF
> > > +	select COMPAT
> > 
> > and avoid the explicit select.
> 
> in patch 20 COMPAT becomes depending also on ARM64_ILP32, like this:
> -       depends on AARCH32_EL0
> +       depends on AARCH32_EL0 || ARM64_ILP32
> 
> So this is a preparation for it. If it looks confusing, I think it's
> better to underline it in the description to the patch in addition to
> this:
> 
> > From now, AARCH32_EL0 (former COMPAT) config option means the support of
> > AARCH32 userspace, ARM64_ILP32 - support of ILP32 ABI (see next patches),
> > and COMPAT indicates that one of them, or both, is enabled.
> 
> But if you prefer, I can do like you suggested here and make COMPAT
> depend on AARCH32_EL0 in the last patch.

What I meant is that if you define COMPAT as "def_bool y", you no longer
need the explicit "select COMPAT". When AARCH32_EL0 is disabled, COMPAT
would automatically be disabled because of the "depends on AARCH32_EL0"
line.

-- 
Catalin

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Re: [PATCH 05/20] arm64: rename COMPAT to AARCH32_EL0 in Kconfig Catalin Marinas <catalin.marinas@arm.com> - 2017-06-08 16:10 +0200
  Re: [PATCH 05/20] arm64: rename COMPAT to AARCH32_EL0 in Kconfig Catalin Marinas <catalin.marinas@arm.com> - 2017-06-09 13:10 +0200

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