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

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Message-ID: <5630D6BA.1080701@oracle.com>
Date:	Wed, 28 Oct 2015 10:07:54 -0400
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	Hanjun Guo <hanjun.guo@...aro.org>,
	Tomasz Nowicki <tomasz.nowicki@...aro.org>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc:	Tomasz Nowicki <tn@...ihalf.com>, bhelgaas@...gle.com,
	arnd@...db.de, will.deacon@....com, catalin.marinas@....com,
	rjw@...ysocki.net, 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
Subject: Re: [Linaro-acpi] [PATCH V1 07/11] XEN / PCI: Remove the dependence
 on arch x86 when PCI_MMCONFIG=y

On 10/28/2015 09:45 AM, Hanjun Guo wrote:
> On 10/28/2015 06:56 PM, Tomasz Nowicki wrote:
>> On 28.10.2015 11:49, Stefano Stabellini wrote:
>>> 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
>>
>> Right, we need:
>> +#include <linux/ecam.h>
>>
>> Will fix this in next version, thanks!
>
> Hmm, I think we just missed the head file, but the logic
> of this patch is still right.
>


Yes, removing the test should be safe.

-boris

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