linux-kernel - Re: [Linaro-acpi] [PATCH V1 07/11] XEN / PCI: Remove the dependence on arch x86 when PCI

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Date:	Wed, 28 Oct 2015 10:49:15 +0000
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
CC:	Tomasz Nowicki <tomasz.nowicki@...aro.org>,
	Tomasz Nowicki <tn@...ihalf.com>, <bhelgaas@...gle.com>,
	<arnd@...db.de>, <will.deacon@....com>, <catalin.marinas@....com>,
	<rjw@...ysocki.net>, <hanjun.guo@...aro.org>,
	<Lorenzo.Pieralisi@....com>, <linux-kernel@...r.kernel.org>,
	<linaro-acpi@...ts.linaro.org>, <linux-pci@...r.kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	<Liviu.Dudau@....com>, <ddaney@...iumnetworks.com>,
	<Narinder.Dhillon@...iumnetworks.com>,
	<linux-acpi@...r.kernel.org>, <robert.richter@...iumnetworks.com>,
	<wangyijing@...wei.com>, <tglx@...utronix.de>,
	<jiang.liu@...ux.intel.com>,
	<linux-arm-kernel@...ts.infradead.org>,
	<Stefano.Stabellini@...citrix.com>
Subject: Re: [Linaro-acpi] [PATCH V1 07/11] XEN / PCI: Remove the dependence
 on arch x86 when PCI_MMCONFIG=y

On Tue, 27 Oct 2015, Boris Ostrovsky wrote:
> On 10/27/2015 12:47 PM, Tomasz Nowicki wrote:
> > + Stefano
> > 
> > On 27.10.2015 17:38, Tomasz Nowicki wrote:
> > > From: Hanjun Guo <hanjun.guo@...aro.org>
> > > 
> > > In drivers/xen/pci.c, there are arch x86 dependent codes when
> > > CONFIG_PCI_MMCONFIG is enabled, since CONFIG_PCI_MMCONFIG
> > > depends on ACPI, so this will prevent XEN PCI running on other
> > > architectures using ACPI with PCI_MMCONFIG enabled (such as ARM64).
> > > 
> > > Fortunatly, it can be sloved in a simple way. In drivers/xen/pci.c,
> > > the only x86 dependent code is if ((pci_probe & PCI_PROBE_MMCONF) == 0),
> > > and it's defined in asm/pci_x86.h, the code means that
> > > if the PCI resource is not probed in PCI_PROBE_MMCONF way, just
> > > ingnore the xen mcfg init. Actually this is duplicate, because
> > > if PCI resource is not probed in PCI_PROBE_MMCONF way, the
> > > pci_mmconfig_list will be empty, and the if (list_empty())
> > > after it will do the same job.
> > > 
> > > So just remove the arch related code and the head file, this
> > > will be no functional change for x86, and also makes xen/pci.c
> > > usable for other architectures.
> > > 
> > > Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
> > > CC: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> > > CC: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> > > ---
> > >   drivers/xen/pci.c | 6 ------
> > >   1 file changed, 6 deletions(-)
> > > 
> > > diff --git a/drivers/xen/pci.c b/drivers/xen/pci.c
> > > index 6785ebb..9a8dbe3 100644
> > > --- a/drivers/xen/pci.c
> > > +++ b/drivers/xen/pci.c
> > > @@ -28,9 +28,6 @@
> > >   #include <asm/xen/hypervisor.h>
> > >   #include <asm/xen/hypercall.h>
> > >   #include "../pci/pci.h"
> > > -#ifdef CONFIG_PCI_MMCONFIG
> > > -#include <asm/pci_x86.h>
> > > -#endif
> 
> Assuming this still compiles on x86 now that this include file is removed
> 
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>

I think it does not:

drivers/xen/pci.c: In function ‘xen_mcfg_late’:
drivers/xen/pci.c:221:18: error: ‘pci_mmcfg_list’ undeclared (first use in this function)
drivers/xen/pci.c:221:18: note: each undeclared identifier is reported only once for each f


> > > 
> > >   static bool __read_mostly pci_seg_supported = true;
> > > 
> > > @@ -222,9 +219,6 @@ static int __init xen_mcfg_late(void)
> > >       if (!xen_initial_domain())
> > >           return 0;
> > > 
> > > -    if ((pci_probe & PCI_PROBE_MMCONF) == 0)
> > > -        return 0;
> > > -
> > >       if (list_empty(&pci_mmcfg_list))
> > >           return 0;
> > > 
> > > 
>