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

From: [email-masked] (Boris Ostrovsky)
Date: Tue, 26 May 2015 09:54:42 -0400

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 <[email-masked]>
> CC: Konrad Rzeszutek Wilk <[email-masked]>
> CC: Boris Ostrovsky <[email-masked]>
> ---
>   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 I am not sure I understand why you are trying to do this since AFAIK 
CONFIG_PCI_MMCONFIG is only defined on x86 so neither pci_x86.h will be 
included nor xen_mcfg_late() will be defined on ARM.

-boris