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Date: Mon, 17 Sep 2012 15:05:16 +0100
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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To: Sergei Shtylyov <sshtylyov@mvista.com>
CC: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>,
        "arnd@arndb.de" <arnd@arndb.de>,
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        Ian Campbell <Ian.Campbell@citrix.com>,
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        "catalin.marinas@arm.com" <catalin.marinas@arm.com>,
        "Tim (Xen.org)" <tim@xen.org>,
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Subject: Re: [PATCH v4 12/24] xen/arm: introduce CONFIG_XEN on ARM
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On Mon, 17 Sep 2012, Sergei Shtylyov wrote:
> Hello.
> 
> On 17-09-2012 14:57, Stefano Stabellini wrote:
> 
> >>> Changes in v2:
> 
> >>> - mark Xen guest support on ARM as EXPERIMENTAL.
> 
> >>> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> >>> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> >>> ---
> >>>   arch/arm/Kconfig |   10 ++++++++++
> >>>   1 files changed, 10 insertions(+), 0 deletions(-)
> 
> >>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> >>> index 2f88d8d..e92518d 100644
> >>> --- a/arch/arm/Kconfig
> >>> +++ b/arch/arm/Kconfig
> >>> @@ -1897,6 +1897,16 @@ config DEPRECATED_PARAM_STRUCT
> >>>   	  This was deprecated in 2001 and announced to live on for 5 years.
> >>>   	  Some old boot loaders still use this way.
> >>>
> >>> +config XEN_DOM0
> >>> +	def_bool y
> >>> +
> >>> +config XEN
> >>> +	bool "Xen guest support on ARM (EXPERIMENTAL)"
> >>> +	depends on EXPERIMENTAL && ARM && OF
> >>> +	select XEN_DOM0
> 
> >>     What's the point of selecting it if it's always "y"?
> 
> > That's because on X86 is not always "y": there are things under
> > drivers/xen that compile on both platforms and depend on XEN_DOM0.
> 
>     But we're not on x86. On ARM this select is pointless.

We need some common code (under drivers/xen) that compiles only if
XEN_DOM0 is selected, so it is not pointless after all.

XEN_DOM0 is not the only symbol that is conditionally compiled on one
architectuire and always "y" on another...