From 3299be2479f9878dd3bb484f2b8f1ef7c0a20fb4 Mon Sep 17 00:00:00 2001 From: Bin Meng Date: Sun, 22 May 2016 01:45:31 -0700 Subject: [PATCH] x86: Don't touch IA32_APIC_BASE MSR on Intel Quark Intel Quark processor core provides an integrated Local APIC but does not support the IA32_APIC_BASE MSR. As a result, the Local APIC is always globally enabled and the Local APIC base address is fixed at 0xfee00000. Attempting to access the IA32_APIC_BASE MSR causes a general protection fault. Signed-off-by: Bin Meng Reviewed-by: Simon Glass --- arch/x86/cpu/lapic.c | 28 ++++++++++++++++------------ 1 file changed, 16 insertions(+), 12 deletions(-) diff --git a/arch/x86/cpu/lapic.c b/arch/x86/cpu/lapic.c index 30d23130eb..dbb32c4447 100644 --- a/arch/x86/cpu/lapic.c +++ b/arch/x86/cpu/lapic.c @@ -65,23 +65,27 @@ void lapic_write(unsigned long reg, unsigned long v) void enable_lapic(void) { - msr_t msr; - - msr = msr_read(MSR_IA32_APICBASE); - msr.hi &= 0xffffff00; - msr.lo |= MSR_IA32_APICBASE_ENABLE; - msr.lo &= ~MSR_IA32_APICBASE_BASE; - msr.lo |= LAPIC_DEFAULT_BASE; - msr_write(MSR_IA32_APICBASE, msr); + if (!IS_ENABLED(CONFIG_INTEL_QUARK)) { + msr_t msr; + + msr = msr_read(MSR_IA32_APICBASE); + msr.hi &= 0xffffff00; + msr.lo |= MSR_IA32_APICBASE_ENABLE; + msr.lo &= ~MSR_IA32_APICBASE_BASE; + msr.lo |= LAPIC_DEFAULT_BASE; + msr_write(MSR_IA32_APICBASE, msr); + } } void disable_lapic(void) { - msr_t msr; + if (!IS_ENABLED(CONFIG_INTEL_QUARK)) { + msr_t msr; - msr = msr_read(MSR_IA32_APICBASE); - msr.lo &= ~MSR_IA32_APICBASE_ENABLE; - msr_write(MSR_IA32_APICBASE, msr); + msr = msr_read(MSR_IA32_APICBASE); + msr.lo &= ~MSR_IA32_APICBASE_ENABLE; + msr_write(MSR_IA32_APICBASE, msr); + } } unsigned long lapicid(void) -- 2.30.2