Commit-ID: d122ab8d224a59aa0c3e4ba3540c6ab99556c3e3 Gitweb: http://git.kernel.org/tip/d122ab8d224a59aa0c3e4ba3540c6ab99556c3e3 Author: Ingo Molnar <mi...@kernel.org> AuthorDate: Fri, 4 Apr 2014 08:41:26 +0200 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Fri, 4 Apr 2014 08:48:03 +0200
[PATCH] x86: Try the BIOS reboot method before the PCI reboot method Steve reported a reboot hang and bisected it back to this commit: a4f1987e4c54 x86, reboot: Add EFI and CF9 reboot methods into the default list He heroically tested all reboot methods and found the following: reboot=t # triple fault ok reboot=k # keyboard ctrl FAIL reboot=b # BIOS ok reboot=a # ACPI FAIL reboot=e # EFI FAIL [system has no EFI] reboot=p # PCI 0xcf9 FAIL And I think it's pretty obvious that we should only try 0xcf9 as a last resort - if at all. The other observation is that (on this box) we should try the 'BIOS' method before the PCI method. Thirdly, CF9_COND is a total misnomer - it should be something like CF9_SAFE or CF9_CAREFUL, and 'CF9' should be 'CF9_FORCE' ... So this patch fixes the worst problems: - it orders the actual reboot logic to follow the reboot ordering pattern - it was in a pretty random order before for no good reason. - it fixes the CF9 misnomers and uses BOOT_CF9_FORCE and BOOT_CF9_SAFE flags to make the code more obvious. - it tries the BIOS reboot method before the PCI reboot method. Reported-and-bisected-by: Steven Rostedt <rost...@goodmis.org> Cc: Li Aubrey <aubrey...@linux.intel.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Matthew Garrett <mj...@srcf.ucam.org> Link: http://lkml.kernel.org/r/20140404064120.gb11...@gmail.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/kernel/reboot.c | 68 +++++++++++++++++++++++++----------------------- include/linux/reboot.h | 14 +++++----- 2 files changed, 43 insertions(+), 39 deletions(-) diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index 654b465..527dbcb 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -114,8 +114,8 @@ EXPORT_SYMBOL(machine_real_restart); */ static int __init set_pci_reboot(const struct dmi_system_id *d) { - if (reboot_type != BOOT_CF9) { - reboot_type = BOOT_CF9; + if (reboot_type != BOOT_CF9_FORCE) { + reboot_type = BOOT_CF9_FORCE; pr_info("%s series board detected. Selecting %s-method for reboots.\n", d->ident, "PCI"); } @@ -468,10 +468,15 @@ void __attribute__((weak)) mach_reboot_fixups(void) * 6) If still alive, write to the PCI IO port 0xCF9 to reboot * 7) If still alive, inform BIOS to do a proper reboot * - * 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 (7) we'll - * try to force a triple fault and then cycle between hitting the keyboard - * controller and doing that + * If the machine is still alive at this stage, it gives up. + * + * We default to following the same pattern, except that we try + * (7) [BIOS] before (6) [PCI], and we add 8): try to force a + * triple fault and then cycle between hitting the keyboard + * controller and doing that. + * + * This means that this function can never return, it can misbehave + * by not rebooting properly and hanging. */ static void native_machine_emergency_restart(void) { @@ -492,6 +497,11 @@ static void native_machine_emergency_restart(void) for (;;) { /* Could also try the reset bit in the Hammer NB */ switch (reboot_type) { + case BOOT_ACPI: + acpi_reboot(); + reboot_type = BOOT_KBD; + break; + case BOOT_KBD: mach_reboot_fixups(); /* For board specific fixups */ @@ -509,43 +519,29 @@ static void native_machine_emergency_restart(void) } break; - case BOOT_TRIPLE: - load_idt(&no_idt); - __asm__ __volatile__("int3"); - - /* We're probably dead after this, but... */ - reboot_type = BOOT_KBD; - break; - - case BOOT_BIOS: - machine_real_restart(MRR_BIOS); - - /* We're probably dead after this, but... */ - reboot_type = BOOT_TRIPLE; - break; - - case BOOT_ACPI: - acpi_reboot(); - reboot_type = BOOT_KBD; - break; - case BOOT_EFI: if (efi_enabled(EFI_RUNTIME_SERVICES)) efi.reset_system(reboot_mode == REBOOT_WARM ? EFI_RESET_WARM : EFI_RESET_COLD, EFI_SUCCESS, 0, NULL); - reboot_type = BOOT_CF9_COND; + reboot_type = BOOT_BIOS; + break; + + case BOOT_BIOS: + machine_real_restart(MRR_BIOS); + + /* We're probably dead after this, but... */ + reboot_type = BOOT_CF9_SAFE; break; - case BOOT_CF9: + case BOOT_CF9_FORCE: port_cf9_safe = true; /* Fall through */ - case BOOT_CF9_COND: + case BOOT_CF9_SAFE: if (port_cf9_safe) { - u8 reboot_code = reboot_mode == REBOOT_WARM ? - 0x06 : 0x0E; + u8 reboot_code = reboot_mode == REBOOT_WARM ? 0x06 : 0x0E; u8 cf9 = inb(0xcf9) & ~reboot_code; outb(cf9|2, 0xcf9); /* Request hard reset */ udelay(50); @@ -553,7 +549,15 @@ static void native_machine_emergency_restart(void) outb(cf9|reboot_code, 0xcf9); udelay(50); } - reboot_type = BOOT_BIOS; + reboot_type = BOOT_TRIPLE; + break; + + case BOOT_TRIPLE: + load_idt(&no_idt); + __asm__ __volatile__("int3"); + + /* We're probably dead after this, but... */ + reboot_type = BOOT_KBD; break; } } diff --git a/include/linux/reboot.h b/include/linux/reboot.h index 9e7db9e..48bf152 100644 --- a/include/linux/reboot.h +++ b/include/linux/reboot.h @@ -20,13 +20,13 @@ enum reboot_mode { extern enum reboot_mode reboot_mode; enum reboot_type { - BOOT_TRIPLE = 't', - BOOT_KBD = 'k', - BOOT_BIOS = 'b', - BOOT_ACPI = 'a', - BOOT_EFI = 'e', - BOOT_CF9 = 'p', - BOOT_CF9_COND = 'q', + BOOT_TRIPLE = 't', + BOOT_KBD = 'k', + BOOT_BIOS = 'b', + BOOT_ACPI = 'a', + BOOT_EFI = 'e', + BOOT_CF9_FORCE = 'p', + BOOT_CF9_SAFE = 'q', }; extern enum reboot_type reboot_type; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
