Re: [RFC v1 7/8] xen: unwrap XEN_BACKEND from XEN_DOM0

["Luis R. Rodriguez" <mcgrof@suse.com>]

On Wed, Feb 25, 2015 at 02:33:40PM +0000, Stefano Stabellini wrote:
> On Wed, 25 Feb 2015, David Vrabel wrote:
> > On 25/02/15 14:17, Stefano Stabellini wrote:
> > > On Wed, 11 Feb 2015, Luis R. Rodriguez wrote:
> > >> From: "Luis R. Rodriguez" <mcgrof@suse.com>
> > >>
> > >> This unwraps XEN_BACKEND from depending on XEN_DOM0, it
> > >> instead makes it depend on the possible x86 backends and
> > >> under what scenerios its allowed under ARM. This is as per
> > >> the agreed upon Xen Kconfig changes [0].
> > >>
> > >> [0] http://comments.gmane.org/gmane.comp.emulators.xen.devel/231579
> > >>
> > >> Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
> > >> ---
> > >>  arch/x86/xen/Kconfig | 2 ++
> > >>  drivers/xen/Kconfig  | 3 ++-
> > >>  2 files changed, 4 insertions(+), 1 deletion(-)
> > >>
> > >> diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
> > >> index 50e2fb4..9298eb3 100644
> > >> --- a/arch/x86/xen/Kconfig
> > >> +++ b/arch/x86/xen/Kconfig
> > >> @@ -16,8 +16,10 @@ config XEN
> > >>  
> > >>  config XEN_DOM0
> > >>  	def_bool y
> > >> +	select XEN_BACKEND
> > >>  	depends on XEN && PCI_XEN && SWIOTLB_XEN
> > >>  	depends on X86_LOCAL_APIC && X86_IO_APIC && ACPI && PCI
> > >> +	depends on XEN_PV || XEN_PVH
> > >>  
> > >>  config XEN_PVHVM
> > >>  	def_bool y
> > >> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> > >> index 31391bc..d8bd3f6 100644
> > >> --- a/drivers/xen/Kconfig
> > >> +++ b/drivers/xen/Kconfig
> > >> @@ -77,7 +77,8 @@ config XEN_DEV_EVTCHN
> > >>  
> > >>  config XEN_BACKEND
> > >>  	bool "Backend driver support"
> > >> -	depends on XEN_DOM0
> > >> +	depends on ARM || ARM64 || (X86 && (XEN_PV || XEN_PVH || XEN_PVHVM))
> > >> +	select SWIOTLB_XEN if ARM || ARM64
> > >>  	default y
> > >>  	help
> > >>  	  Support for backend device drivers that provide I/O services
> > > 
> > > If you do this people could enable XEN_BACKEND without XEN on ARM.
> > > I think it needs to be:
> > > 
> > > depends on (XEN && (ARM || ARM64)) || (X86 && (XEN_PV || XEN_PVH || XEN_PVHVM))
> > 
> > It's this more sufficiently:
> > 
> > depends on XEN ?
> 
> Yeah :-)

We already only expose this option on the top of the Kconfig file with
'if XEN' language, folding XEN_PVHVM under XEN_FRONTEND might not suffice
to ensure everything builds fine here given CONFIG_XEN does not implicate
XEN_FRONTEND. Because of this I think the above is still required.

Let me know though, I'll send a v4 of what things look like (no code changes)
right now before moving on again.

  Luis