Re: [PATCH 10/11] XEN / PCI: Remove the dependence on arch x86 when PCI_MMCONFIG=y

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 05/26/2015 10:54 AM, Tomasz Nowicki wrote:
> On 26.05.2015 16:00, Boris Ostrovsky wrote:
>> On 05/26/2015 09:54 AM, Boris Ostrovsky wrote:
>>> On 05/26/2015 08:49 AM, Hanjun Guo wrote:
>>>> 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@linaro.org>
>>>> CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
>>>> CC: Boris Ostrovsky <boris.ostrovsky@oracle.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
>>>>
>>>>   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;
>>>>
>>>
>>> (+Stefano who is Xen ARM maintainer)
>>>
>>> This will not build on x86 since pci_mmcfg_list since, for example,
>>> pci_mmcfg_list is declared in pci_x86.h.
>>
>>
>> And now really with Stefano and with parsable first sentence, sorry:
>>
>>
>> This will not build on x86 since pci_mmcfg_list, for example, is
>> declared in pci_x86.h.
>
> With this patch set, not any more. Please see preceding patches.


OK, I didn't notice this was part of a series.

Then if not having PCI_PROBE_MMCONF bit set is indeed equivalent to 
list_empty(&pci_mmcfg_list), is there any reason for this flag to 
(continue to) exist? (and also for pci_mmcfg_arch_init_failed.)


-boris