On Thu, Mar 12, 2015 at 02:42:01AM -0600, Jan Beulich wrote: > >>> On 12.03.15 at 00:10, <mcgrof@xxxxxxxxxxxxxxxx> wrote: > > 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 > > I.e. building a 32-bit kernel with APIC support but with !SMP, !PCI_MSI, > and !X86_32_NON_STANDARD will now be impossible. These are the requirements for X86_UP_APIC though. > Surely not what the patch description says. The only removal I see here is the option to opt-in or out of X86_UP_APIC when PCI_MSI is *not* enabled provided you meet the requirements. > > --- 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 > > I don't see the need for the latter - MSI specifically works without > any IO-APIC interaction. Although it can some MSI platforms need it as Bryan originally had expressed in his original patch [0] that Intel CE, Intel MID and Intel Quark are all 32-bit uniprocessor systems with IO-APICs that also use PCI-MSI, so this is not a hard requirement but rather compromising on enabling it since the the X86_IOAPIC cost is only ~12 KiB at with no performance penalty. https://lkml.org/lkml/2015/1/22/718 > And for the former you should decide > which way you want it - PCI_MSI select X86_LOCAL_APIC > (probably the right thing in x86, but surely wrong everwhere > else, i.e. this at least needs a condition tagged onto it) selects are done *iff* the dependencies are met, otherwise we can't select it, that's all, so the *iff* is implicit. > or > X86_LOCAL_APIC depend on PCI_MSI; in no case should this > be a forward _and_ reverse dependency. There is no reverse requirement here because of the select. The trick here is the select implies the depends the value you are selecting has. mcgrof@ergon ~/linux-next (git::master)$ export ARCH=alpha mcgrof@ergon ~/linux-next (git::master)$ make allnoconfig mcgrof@ergon ~/linux-next (git::master)$ make menuconfig --> System setup ---> [*] Message Signaled Interrupts (MSI and MSI-X) mcgrof@ergon ~/linux-next (git::master)$ grep -i APIC .config mcgrof@ergon ~/linux-next (git::master)$ echo $? 1 Luis -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
