diff options
| -rw-r--r-- | src/arch/x86/ioapic.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/src/arch/x86/ioapic.c b/src/arch/x86/ioapic.c index 84a4c7f7bc..04c852b4c2 100644 --- a/src/arch/x86/ioapic.c +++ b/src/arch/x86/ioapic.c @@ -147,7 +147,12 @@ static void set_ioapic_id(void *ioapic_base, u8 ioapic_id) u8 get_ioapic_id(void *ioapic_base) { - return (io_apic_read(ioapic_base, 0x00) >> 24) & 0x0f; + /* + * According to 82093AA I/O ADVANCED PROGRAMMABLE INTERRUPT CONTROLLER (IOAPIC) + * only 4 bits (24:27) are used for the ID. In practice the upper bits are either + * always 0 or used for larger IDs. + */ + return (io_apic_read(ioapic_base, 0x00) >> 24) & 0xff; } u8 get_ioapic_version(void *ioapic_base) |