Messages in this thread Patch in this message | | | From | Bryan O'Donoghue <> | Subject | [PATCH] x86: Re-enable IO-APIC for non-SMP X86_32 | Date | Thu, 22 Jan 2015 22:58:49 +0000 |
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Commit 0dbc6078c06bc0 ('x86, build, pci: Fix PCI_MSI build on !SMP') introduced the dependency that X86_UP_APIC should only be visible only when PCI_MSI is false.
Conceptually this is invalid since any x86 system that supports MSIs must have an LAPIC to receive those messages. An MSI is written directly to the LAPIC of the CPU servicing the interrupt.
Making X86_UP_APIC depend on !PCI_MSI means that X86_UP_IOAPIC will be false since X86_UP_IOAPIC depends on X86_UP_APIC. It also means that X86_IO_APIC cannot be true.
In other words no 32 bit uniprocessor system that supports MSIs can have an IO-APIC, which is an architectually invalid statement.
This patch removes the dependency on !PCI_MSI for X86_UP_APIC and as a consequence re-enables support for IO-APIC on 32 bit uniprocessor X86 systems.
Since Intel CE, Intel MID and Intel Quark are all 32-bit uniprocessor systems with an IO-APIC re-enabling IO-APIC for 32-bit x86 is required.
Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> --- arch/x86/Kconfig | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ba397bd..0dc9d01 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -857,7 +857,7 @@ source "kernel/Kconfig.preempt" config X86_UP_APIC bool "Local APIC support on uniprocessors" - depends on X86_32 && !SMP && !X86_32_NON_STANDARD && !PCI_MSI + depends on X86_32 && !SMP && !X86_32_NON_STANDARD ---help--- A local APIC (Advanced Programmable Interrupt Controller) is an integrated interrupt controller in the CPU. If you have a single-CPU @@ -868,6 +868,10 @@ config X86_UP_APIC performance counters), and the NMI watchdog which detects hard lockups. +config X86_UP_APIC_MSI + def_bool y + select X86_UP_APIC if X86_32 && !SMP && !X86_32_NON_STANDARD && PCI_MSI + config X86_UP_IOAPIC bool "IO-APIC support on uniprocessors" depends on X86_UP_APIC -- 1.9.1
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