linux-kernel - Re: [PATCH] arm/xen: Remove definiition of virt_to

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Message-ID: <alpine.DEB.2.02.1405071758070.14596@kaball.uk.xensource.com>
Date:	Wed, 7 May 2014 17:58:21 +0100
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	David Vrabel <david.vrabel@...rix.com>
CC:	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Julien Grall <julien.grall@...aro.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <xen-devel@...ts.xenproject.org>,
	Ian Campbell <ian.campbell@...rix.com>,
	<konrad.wilk@...cle.com>, Catalin Marinas <catalin.marinas@....com>
Subject: Re: [PATCH] arm/xen: Remove definiition of virt_to_pfn in
 asm/xen/page.h

On Wed, 7 May 2014, David Vrabel wrote:
> On 07/05/14 12:41, Stefano Stabellini wrote:
> > On Fri, 25 Apr 2014, Stefano Stabellini wrote:
> >> On Thu, 24 Apr 2014, David Vrabel wrote:
> >>> On 24/04/14 13:49, Julien Grall wrote:
> >>>> Hi David,
> >>>>
> >>>> On 04/24/2014 01:22 PM, David Vrabel wrote:
> >>>>> On 18/04/14 16:54, Julien Grall wrote:
> >>>>>> virt_to_pfn has been defined in asm/memory.h by the commit e26a9e0 "ARM: Better
> >>>>>> virt_to_page() handling"
> >>>>>>
> >>>>>> This will result of a compilation warning when CONFIG_XEN is enabled.
> >>>>>>
> >>>>>> arch/arm/include/asm/xen/page.h:80:0: warning: "virt_to_pfn" redefined [enabled by default]
> >>>>>>  #define virt_to_pfn(v)          (PFN_DOWN(__pa(v)))
> >>>>>>  ^
> >>>>>> In file included from arch/arm/include/asm/page.h:163:0,
> >>>>>>                  from arch/arm/include/asm/xen/page.h:4,
> >>>>>>                  from include/xen/page.h:4,
> >>>>>>                  from arch/arm/xen/grant-table.c:33:
> >>>>>>
> >>>>>> The definition in memory.h is nearly the same (it directly expand PFN_DOWN),
> >>>>>> so we can safely drop virt_to_pfn in xen include.
> >>>>>
> >>>>>
> >>>>> This breaks the arm build for me.
> >>>>>
> >>>>> /local/davidvr/work/k.org/tip/drivers/block/xen-blkfront.c: In function
> >>>>> ‘setup_blkring’:
> >>>>> /local/davidvr/work/k.org/tip/drivers/block/xen-blkfront.c:1236:2:
> >>>>> error: implicit declaration of function ‘virt_to_pfn’
> >>>>> [-Werror=implicit-function-declaration]
> >>>>>   err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
> >>>>>   ^
> >>>>
> >>>> I don't have any issue to build the following branch with this patch on:
> >>>> 	- v3.15-rc2
> >>>> 	- xentip master
> >>>> 	- xentip for-linus-3.16
> >>>
> >>> Applied to devel/for-linus-3.16.
> >>>
> >>> If something else turns up for 3.15 (and I remember) I'll take it for
> >>> 3.15 instead.
> >>
> >> David,
> >> thank you very much for taking the patch in my absence.
> >>
> >> Considering that the problem is affecting everybody enabling CONFIG_XEN
> >> on ARM on v3.15, I don't think we can wait for the next merge window to
> >> send this fix upstream.
> >> Too many warnings for too many people.
> > 
> > Unfortunately this commit breaks arm64 compilation, as virt_to_pfn has
> > not been introduced to arm64/include/asm/memory.h.
> > Has the patch been sent upstream yet?
> 
> No.
> 
> > We need this additional change for arm64:
> > 
> > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> > index e94f945..993bce5 100644
> > --- a/arch/arm64/include/asm/memory.h
> > +++ b/arch/arm64/include/asm/memory.h
> > @@ -138,6 +138,7 @@ static inline void *phys_to_virt(phys_addr_t x)
> >  #define __pa(x)			__virt_to_phys((unsigned long)(x))
> >  #define __va(x)			((void *)__phys_to_virt((phys_addr_t)(x)))
> >  #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
> > +#define virt_to_pfn(x)      __phys_to_pfn(__virt_to_phys(x))
> 
> This would need an ack from an arm64 maintainer.

Certainly. Catalin is in CC.