[+cc Konrad]
On Thu, Oct 3, 2013 at 3:59 AM, Thomas Petazzoni
<thomas.petazz...@free-electrons.com> wrote:
> Commit ebd97be635 ('PCI: remove ARCH_SUPPORTS_MSI kconfig option')
> removed the ARCH_SUPPORTS_MSI option which architectures could select
> to indicate that they support MSI. Now, all architectures are supposed
> to build fine when MSI support is enabled: instead of having the
> architecture tell *when* MSI support can be used, it's up to the
> architecture code to ensure that MSI support can be enabled.
>
> On x86, commit ebd97be635 removed the following line:
>
> select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
>
> Which meant that MSI support was only available when the local APIC
> and I/O APIC were enabled. While this is always true on SMP or x86-64,
> it is not necessarily the case on i386 !SMP.
>
> The below patch makes sure that the local APIC and I/O APIC support is
> always enabled when MSI support is enabled. To do so, it:
>
> * Ensures the X86_UP_APIC option is not visible when PCI_MSI is
> enabled. This is the option that allows, on UP machines, to enable
> or not the APIC support. It is already not visible on SMP systems,
> or x86-64 systems, for example. We're simply also making it
> invisible on i386 MSI systems.
>
> * Ensures that the X86_LOCAL_APIC and X86_IO_APIC options are 'y'
> when PCI_MSI is enabled.
>
> Notice that this change requires a change in drivers/iommu/Kconfig to
> avoid a recursive Kconfig dependencey. The AMD_IOMMU option selects
> PCI_MSI, but was depending on X86_IO_APIC. This dependency is no
> longer needed: as soon as PCI_MSI is selected, the presence of
> X86_IO_APIC is guaranteed. Moreover, the AMD_IOMMU already depended on
> X86_64, which already guaranteed that X86_IO_APIC was enabled, so this
> dependency was anyway redundant.
>
> Signed-off-by: Thomas Petazzoni <thomas.petazz...@free-electrons.com>
> Reported-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
> Cc: bhelg...@google.com
> Cc: b...@kernel.crashing.org
> Cc: daniel.pr...@gmail.com
> Cc: thierry.red...@gmail.com
> Cc: linux-kernel@vger.kernel.org
> Cc: ja...@lakedaemon.net
> Cc: x...@kernel.org
FWIW,
Acked-by: Bjorn Helgaas <bhelg...@google.com>
x86 maintainers, I assume you'll pick this up. Let me know if you
want me to do it.
Bjorn
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