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x86: Allow platforms to force enable apic

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Some embedded x86 platforms don't setup the APIC in the
BIOS/bootloader and would be forced to add "lapic" on the kernel
command line. That's a bit akward.

Split out the force enable code from detect_init_APIC() and allow
platform code to call it from the platform setup. That avoids the
command line parameter and possible replication of the MSR dance in
the force enable code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1287510389-8388-1-git-send-email-dirk.brandewie@gmail.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
This commit is contained in:
Thomas Gleixner 2010-10-19 10:46:28 -07:00
parent d4429f608a
commit 5a7ae78fd4
2 changed files with 55 additions and 33 deletions
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1
arch/x86/include/asm/apic.h
View file

@ -238,6 +238,7 @@ extern void setup_boot_APIC_clock(void);
extern void setup_secondary_APIC_clock(void);
extern int APIC_init_uniprocessor(void);
extern void enable_NMI_through_LVT0(void);
extern int apic_force_enable(void);
/*
* On 32bit this is mach-xxx local

87
arch/x86/kernel/apic/apic.c
View file

@ -1531,13 +1531,60 @@ static int __init detect_init_APIC(void)
return 0;
}
#else
static int apic_verify(void)
{
u32 features, h, l;
/*
* The APIC feature bit should now be enabled
* in `cpuid'
*/
features = cpuid_edx(1);
if (!(features & (1 << X86_FEATURE_APIC))) {
pr_warning("Could not enable APIC!\n");
return -1;
}
set_cpu_cap(&boot_cpu_data, X86_FEATURE_APIC);
mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
/* The BIOS may have set up the APIC at some other address */
rdmsr(MSR_IA32_APICBASE, l, h);
if (l & MSR_IA32_APICBASE_ENABLE)
mp_lapic_addr = l & MSR_IA32_APICBASE_BASE;
pr_info("Found and enabled local APIC!\n");
return 0;
}
int apic_force_enable(void)
{
u32 h, l;
if (disable_apic)
return -1;
/*
* Some BIOSes disable the local APIC in the APIC_BASE
* MSR. This can only be done in software for Intel P6 or later
* and AMD K7 (Model > 1) or later.
*/
rdmsr(MSR_IA32_APICBASE, l, h);
if (!(l & MSR_IA32_APICBASE_ENABLE)) {
pr_info("Local APIC disabled by BIOS -- reenabling.\n");
l &= ~MSR_IA32_APICBASE_BASE;
l |= MSR_IA32_APICBASE_ENABLE | APIC_DEFAULT_PHYS_BASE;
wrmsr(MSR_IA32_APICBASE, l, h);
enabled_via_apicbase = 1;
}
return apic_verify();
}
/*
* Detect and initialize APIC
*/
static int __init detect_init_APIC(void)
{
u32 h, l, features;
/* Disabled by kernel option? */
if (disable_apic)
return -1;
@ -1567,38 +1614,12 @@ static int __init detect_init_APIC(void)
"you can enable it with \"lapic\"\n");
return -1;
}
/*
* Some BIOSes disable the local APIC in the APIC_BASE
* MSR. This can only be done in software for Intel P6 or later
* and AMD K7 (Model > 1) or later.
*/
rdmsr(MSR_IA32_APICBASE, l, h);
if (!(l & MSR_IA32_APICBASE_ENABLE)) {
pr_info("Local APIC disabled by BIOS -- reenabling.\n");
l &= ~MSR_IA32_APICBASE_BASE;
l |= MSR_IA32_APICBASE_ENABLE | APIC_DEFAULT_PHYS_BASE;
wrmsr(MSR_IA32_APICBASE, l, h);
enabled_via_apicbase = 1;
}
if (apic_force_enable())
return -1;
} else {
if (apic_verify())
return -1;
}
/*
* The APIC feature bit should now be enabled
* in `cpuid'
*/
features = cpuid_edx(1);
if (!(features & (1 << X86_FEATURE_APIC))) {
pr_warning("Could not enable APIC!\n");
return -1;
}
set_cpu_cap(&boot_cpu_data, X86_FEATURE_APIC);
mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
/* The BIOS may have set up the APIC at some other address */
rdmsr(MSR_IA32_APICBASE, l, h);
if (l & MSR_IA32_APICBASE_ENABLE)
mp_lapic_addr = l & MSR_IA32_APICBASE_BASE;
pr_info("Found and enabled local APIC!\n");
apic_pm_activate();