Commit-ID: 60d79fd99ff3b9c692b260a4d53a203f537c052a Gitweb: http://git.kernel.org/tip/60d79fd99ff3b9c692b260a4d53a203f537c052a Author: Yinghai Lu <yinghai@xxxxxxxxxx> AuthorDate: Tue, 7 Dec 2010 00:59:49 -0800 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Thu, 9 Dec 2010 21:52:05 +0100 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@xxxxxxxxxx> Cc: Sebastian Siewior <bigeasy@xxxxxxxxxxxxx> LKML-Reference: <4CFDF785.7010401@xxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- 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 4abf08a..8a02150 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); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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