Messages in this thread Patch in this message | | | From | davej@redhat ... | Subject | [PATCH] Disable APIC on reboot. | Date | Mon, 11 Aug 2003 14:40:24 +0100 |
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Forward port of a patch from Felix [surname mangled by MTA] <fxkuehl@gmx.de>
Original mail:-
when I reboot my laptop the BIOS complains about a keyboard controller failure and timer interrupts not working. On the BIOS password screen the keyboard doesn't work. If I disable the BIOS password the system hangs a bit later on the POST screen. I tried all reboot methods via the kernel command line without success. I saw this problem with Debian Woody's precompiled 2.4.18 kernel, self compiled Debian 2.4.20 sources and Linux 2.4.21-rc1+ACPI patch. This problem only occurs if CONFIG_X86_LOCAL_APIC is enabled. With CONFIG_X86_LOCAL_APIC disabled it reboots just fine.
My guess is that it's a BIOS bug as I've never had this problem on other machines before. I found a workaround: disable the local APIC before rebooting. I don't really know how it works. Just calling disable_local_APIC wasn't enough, so I copied a bit more code from apic_pm_suspend (arch/i386/kernel/apic.c:465) to machine_restart (arch/i386/kernel/process.c:369). I'm pretty sure that this is not the proper way to do it but it works here. A patch against 2.4.21-rc1 can be found at the end of this email.
diff -urpN --exclude-from=/home/davej/.exclude bk-linus/arch/i386/kernel/reboot.c linux-2.5/arch/i386/kernel/reboot.c --- bk-linus/arch/i386/kernel/reboot.c 2003-05-13 11:51:12.000000000 +0100 +++ linux-2.5/arch/i386/kernel/reboot.c 2003-07-16 02:54:29.000000000 +0100 @@ -8,6 +8,7 @@ #include <linux/interrupt.h> #include <linux/mc146818rtc.h> #include <asm/uaccess.h> +#include <asm/apic.h> #include "mach_reboot.h" /* @@ -250,6 +251,19 @@ void machine_restart(char * __unused) */ smp_send_stop(); disable_IO_APIC(); +#else +#ifdef CONFIG_X86_LOCAL_APIC + { + unsigned int l, h; + + local_irq_disable(); + disable_local_APIC(); + rdmsr(MSR_IA32_APICBASE, l, h); + l &= ~MSR_IA32_APICBASE_ENABLE; + wrmsr(MSR_IA32_APICBASE, l, h); + local_irq_enable(); +} +#endif #endif if(!reboot_thru_bios) { - 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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