Now, there are many switches in kernel which are used to determine
the final interrupt delivery mode, as shown below:
1) kconfig:
CONFIG_X86_64; CONFIG_X86_LOCAL_APIC; CONFIG_x86_IO_APIC
2) kernel option: disable_apic; skip_ioapic_setup
3) CPU Capability: boot_cpu_has(X86_FEATURE_APIC)
4) MP table: smp_found_config
5) ACPI: acpi_lapic; acpi_ioapic; nr_ioapic
These switches are disordered and scattered and there are also some
dependencies with each other. These make the code difficult to
maintain and read.
Construct a selector to unify them into a single function, then,
Use this selector to get an interrupt delivery mode directly.
Signed-off-by: Dou Liyang <douly.f...@cn.fujitsu.com>
---
arch/x86/kernel/apic/apic.c | 59 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 59 insertions(+)
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 98b3dd8..01bde03 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1235,6 +1235,65 @@ void __init sync_Arb_IDs(void)
APIC_INT_LEVELTRIG | APIC_DM_INIT);
}
+enum apic_intr_mode {
+ APIC_PIC,
+ APIC_VIRTUAL_WIRE,
+ APIC_SYMMETRIC_IO,
+};
+
+static int __init apic_intr_mode_select(void)
+{
+ /* Check kernel option */
+ if (disable_apic) {
+ pr_info("APIC disabled via kernel command line\n");
+ return APIC_PIC;
+ }
+
+ /* Check BIOS */
+#ifdef CONFIG_X86_64
+ /* On 64-bit, the APIC must be integrated, Check local APIC only */
+ if (!boot_cpu_has(X86_FEATURE_APIC)) {
+ disable_apic = 1;
+ pr_info("APIC disabled by BIOS\n");
+ return APIC_PIC;
+ }
+#else
+ /*
+ * On 32-bit, check whether there is a separate chip or integrated
+ * APIC
+ */
+
+ /* Has a separate chip ? */
+ if (!boot_cpu_has(X86_FEATURE_APIC) && !smp_found_config) {
+ disable_apic = 1;
+
+ return APIC_PIC;
+ }
+
+ /* Has a local APIC ? */
+ if (!boot_cpu_has(X86_FEATURE_APIC) &&
+ APIC_INTEGRATED(boot_cpu_apic_version)) {
+ disable_apic = 1;
+ pr_err(FW_BUG "Local APIC %d not detected, force emulation\n",
+ boot_cpu_physical_apicid);
+
+ return APIC_PIC;
+ }
+#endif
+
+ /* Check MP table or ACPI MADT configuration */
+ if (!smp_found_config) {
+ disable_ioapic_support();
+
+ if (!acpi_lapic)
+ pr_info("APIC: ACPI MADT or MP tables are not
detected\n");
+
+ return APIC_VIRTUAL_WIRE;
+ }
+
+ return APIC_SYMMETRIC_IO;
+}
+
/*
* An initial setup of the virtual wire mode.
*/
--
2.5.5
