diff options
| author | Yinghai Lu <yinghai@kernel.org> | 2010-12-07 00:59:49 -0800 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2010-12-09 21:52:05 +0100 |
| commit | 60d79fd99ff3b9c692b260a4d53a203f537c052a (patch) | |
| tree | ee4abd4262825715f9a8d4f773229429bf9aa8ea /arch/x86 | |
| parent | 0450193bffed6e4b6160c4a5ccb0df158eba7d2a (diff) | |
x86, ioapic: Avoid writing io_apic id if already correct
For 32bit mptable path, setup_ids_from_mpc() always writes the io_apic
id register, even there is no change needed.
Skip the write, when readout and mptable match.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
LKML-Reference: <4CFDF785.7010401@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/apic/io_apic.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 4abf08aab3d..8a0215042a5 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -2007,9 +2007,12 @@ void __init setup_ioapic_ids_from_mpc_nocheck(void) = mp_ioapics[apic_id].apicid; /* - * Read the right value from the MPC table and - * write it into the ID register. + * Update the ID register according to the right value + * from the MPC table if they are different. */ + if (mp_ioapics[apic_id].apicid == reg_00.bits.ID) + continue; + apic_printk(APIC_VERBOSE, KERN_INFO "...changing IO-APIC physical APIC ID to %d ...", mp_ioapics[apic_id].apicid); |