From 660e34cebf0a11d54f2d5dd8838607452355f321 Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Mon, 4 Apr 2011 13:55:05 -0400 Subject: [PATCH] x86: Reorder reboot method preferences We have a never ending stream of 'reboot quirks' for new boxes that will not reboot properly under Linux (they will hang on reboot). The reason is widespread 'Windows compatible' assumption of modern x86 hardware, which expects the following reboot sequence: - hitting the ACPI reboot vector (if available) - trying the keyboard controller - hitting the ACPI reboot vector again - then giving the keyboard controller one last go This sequence expectation gets more and more embedded in modern hardware, which often lacks a keyboard controller and may even lock up if the legacy io ports are hit - and which hardware is often not tested with Linux during development. The end result is that reboot works under Windows-alike OSs but not under Linux. Rework our reboot process to meet this hardware externality a little better and match this assumption of newer x86 hardware. In addition to the ACPI,kbd,ACPI,kbd sequence we'll still fall through to attempting a legacy triple fault if nothing else works - and keep trying that and the kbd reset. Signed-off-by: Matthew Garrett [ this commit will also save special casing Oaktrail boards ] Acked-by: Alan Cox Cc: Linus Torvalds Cc: Andrew Morton Cc: Leann Ogasawara Cc: Dave Jones Cc: Len Brown LKML-Reference: <1301939705-2404-1-git-send-email-mjg@redhat.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/reboot.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index 08c44b08bf5b..0c016f727695 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -36,7 +36,7 @@ EXPORT_SYMBOL(pm_power_off); static const struct desc_ptr no_idt = {}; static int reboot_mode; -enum reboot_type reboot_type = BOOT_KBD; +enum reboot_type reboot_type = BOOT_ACPI; int reboot_force; #if defined(CONFIG_X86_32) && defined(CONFIG_SMP) @@ -478,9 +478,24 @@ void __attribute__((weak)) mach_reboot_fixups(void) { } +/* + * Windows compatible x86 hardware expects the following on reboot: + * + * 1) If the FADT has the ACPI reboot register flag set, try it + * 2) If still alive, write to the keyboard controller + * 3) If still alive, write to the ACPI reboot register again + * 4) If still alive, write to the keyboard controller again + * + * If the machine is still alive at this stage, it gives up. We default to + * following the same pattern, except that if we're still alive after (4) we'll + * try to force a triple fault and then cycle between hitting the keyboard + * controller and doing that + */ static void native_machine_emergency_restart(void) { int i; + int attempt = 0; + int orig_reboot_type = reboot_type; if (reboot_emergency) emergency_vmx_disable_all(); @@ -502,6 +517,13 @@ static void native_machine_emergency_restart(void) outb(0xfe, 0x64); /* pulse reset low */ udelay(50); } + if (attempt == 0 && orig_reboot_type == BOOT_ACPI) { + attempt = 1; + reboot_type = BOOT_ACPI; + } else { + reboot_type = BOOT_TRIPLE; + } + break; case BOOT_TRIPLE: load_idt(&no_idt); -- 2.39.5