Messages in this thread Patch in this message | | | Date | Thu, 14 Oct 2004 23:27:19 +0100 (BST) | From | "Maciej W. Rozycki" <> | Subject | Re: 2.6.9-rc4 No local APIC present or hardware disabled |
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On Thu, 14 Oct 2004, Mikael Pettersson wrote:
> There are systems, such as the P3-based Dell Inspirons and Latitutes > that caused the dmi blacklist to be implemented, that fail whether > they're using APM or ACPI. So in the interest of consistency, we should > either always automatically override the BIOS, requiring "nolapic" on > broken systems, or never automatically override the BIOS, requiring > "lapic" on systems that work but have stupid BIOSen.
It's a pity another useful feature gets disfavored due to firmware bugs in newer systems.
> None of this is ACPI-specific, so I don't like the idea of tying > auto-enable/disable to ACPI.
I hope I won't hit the length limit of the command line this way, sigh...
Anyway, if this is going to stay in, I think code needs to be cleaned up to get rid of dead bits and inaccurate comments. Here's my proposal. Does it make sense? I hope so.
Maciej
patch-2.6.9-rc4-lapic-6 diff -up --recursive --new-file linux-2.6.9-rc4.macro/arch/i386/kernel/apic.c linux-2.6.9-rc4/arch/i386/kernel/apic.c --- linux-2.6.9-rc4.macro/arch/i386/kernel/apic.c 2004-10-12 23:57:01.000000000 +0000 +++ linux-2.6.9-rc4/arch/i386/kernel/apic.c 2004-10-14 21:42:57.000000000 +0000 @@ -667,7 +667,7 @@ static int __init detect_init_APIC (void u32 h, l, features; extern void get_cpu_vendor(struct cpuinfo_x86*); - /* Disabled by DMI scan or kernel option? */ + /* Disabled by kernel option? */ if (enable_local_apic < 0) return -1; @@ -681,8 +681,7 @@ static int __init detect_init_APIC (void break; goto no_apic; case X86_VENDOR_INTEL: - if (boot_cpu_data.x86 == 6 || - (boot_cpu_data.x86 == 15 && (cpu_has_apic || enable_local_apic > 0)) || + if (boot_cpu_data.x86 == 6 || boot_cpu_data.x86 == 15 || (boot_cpu_data.x86 == 5 && cpu_has_apic)) break; goto no_apic; @@ -692,15 +691,20 @@ static int __init detect_init_APIC (void if (!cpu_has_apic) { /* - * Over-ride BIOS and try to enable LAPIC - * only if "lapic" specified + * Over-ride BIOS and try to enable the local + * APIC only if "lapic" specified. */ - if (enable_local_apic != 1) - goto no_apic; + if (enable_local_apic <= 0) { + printk("Not enabling local APIC " + "because of frequent BIOS bugs\n"); + printk("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 and AMD K7 (Model > 1). + * software for Intel P6, Intel P4 and AMD K7 + * (Model > 1). */ rdmsr(MSR_IA32_APICBASE, l, h); if (!(l & MSR_IA32_APICBASE_ENABLE)) { - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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