From: "Luis R. Rodriguez" <mcg...@suse.com>
X86_UP_APIC is used for two reasons on 32-bit systems:
1) set a series of dependencies under which we would like
to express we want X86_LOCAL_APIC enabled
2) under the above conditions if PCI_MSI is enabled always
force X86_LOCAL_APIC to be enabled
3) Let users opt in or out of X86_LOCAL_APIC if PCI_MSI is
not enabled
We don't really need a Kconfig entry to address 1) for 2) and 3)
as X86_LOCAL_APIC already has the dependencies which we wish to
match. Instead since 2) is desirable we can just select
X86_LOCAL_APIC on PCI_MSI and it will be enabled when the
dependencies are met. The only thing we loose with this then
is letting users elect to enable or not X86_LOCAL_APIC on
UP 32-bit systems but since:
a) enabling X86_LOCAL_APIC will in no way slow down your kernel
b) enabling X86_LOCAL_APIC only increases your kernel
by 19264 bytes (19 KiB)
c) x86 is not in a state of flux
We can compromise here and just always enable X86_LOCAL_APIC
when PCI_MSI is enabled.
Using:
(a hacked up patch to enable X86_LOCAL_APIC any time)
export ARCH=i386
make allnoconfig
--> Enabling or disabling X86_LOCAL_APIC
make localyesconfig
With X86_LOCAL_APIC:
mcgrof@ergon ~/linux-next (git::master)$ du -b arch/x86/boot/bzImage
508496 arch/x86/boot/bzImage
With X86_LOCAL_APIC:
mcgrof@ergon ~/linux-next (git::master)$ du -b arch/x86/boot/bzImage
489232 arch/x86/boot/bzImage
Cc: David Rientjes <rient...@google.com>
Cc: Bjorn Helgaas <bhelg...@google.com>
Cc: Bryan O'Donoghue <pure.lo...@nexus-software.ie>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Andy Shevchenko <andy.shevche...@gmail.com>
Cc: Thomas Petazzoni <thomas.petazz...@free-electrons.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Borislav Petkov <b...@suse.de>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Jan Beulich <jbeul...@suse.com>
Cc: Juergen Gross <jgr...@suse.com>
Cc: linux-...@vger.kernel.org
Cc: x...@kernel.org
Signed-off-by: Luis R. Rodriguez <mcg...@suse.com>
---
arch/x86/Kconfig | 17 +----------------
drivers/pci/Kconfig | 2 ++
2 files changed, 3 insertions(+), 16 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b17a8ea..37d3e6e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -895,24 +895,9 @@ config UP_LATE_INIT
def_bool y
depends on !SMP && X86_LOCAL_APIC
-config X86_UP_APIC
- bool "Local APIC support on uniprocessors" if !PCI_MSI
- default PCI_MSI
- depends on X86_32 && !SMP && !X86_32_NON_STANDARD
- select X86_IO_APIC
- ---help---
- A local APIC (Advanced Programmable Interrupt Controller) is an
- integrated interrupt controller in the CPU. If you have a single-CPU
- system which has a processor with a local APIC, you can say Y here to
- enable and use it. If you say Y here even though your machine doesn't
- have a local APIC, then the kernel will still run with no slowdown at
- all. The local APIC supports CPU-generated self-interrupts (timer,
- performance counters), and the NMI watchdog which detects hard
- lockups.
-
config X86_LOCAL_APIC
def_bool y
- depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC ||
PCI_MSI
+ depends on X86_64 || SMP || X86_32_NON_STANDARD || PCI_MSI
select GENERIC_IRQ_LEGACY_ALLOC_HWIRQ
config X86_IO_APIC
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index 7a8f1c5..fa9739e 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -5,6 +5,8 @@ config PCI_MSI
bool "Message Signaled Interrupts (MSI and MSI-X)"
depends on PCI
select GENERIC_MSI_IRQ
+ select X86_LOCAL_APIC
+ select X86_IO_APIC
help
This allows device drivers to enable MSI (Message Signaled
Interrupts). Message Signaled Interrupts enable a device to
--
2.3.2.209.gd67f9d5.dirty
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