On Thu, 2019-08-29 at 15:34 +0100, Bradford, Robert wrote: > On Thu, 2019-08-29 at 14:18 +0200, Thomas Gleixner wrote: > > On Thu, 29 Aug 2019, Rob Bradford wrote: > > > > CC+ Ard > > > > > Replace the check using efi_runtime_disabled() which only checks > > > if > > > EFI > > > runtime was disabled on the kernel command line with a call to > > > efi_enabled(EFI_RUNTIME_SERVICES) to check if EFI runtime > > > services > > > are > > > available. > > > > > > In the situation where the kernel was booted without an EFI > > > environment > > > then only efi_enabled(EFI_RUNTIME_SERVICES) correctly represents > > > that no > > > EFI is available. Setting "noefi" or "efi=noruntime" on the > > > commandline > > > continue to have the same effect as > > > efi_enabled(EFI_RUNTIME_SERVICES) > > > will return false. > > > > > > > > > Signed-off-by: Rob Bradford <robert.bradf...@intel.com> > > > --- > > > arch/x86/kernel/reboot.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c > > > index 09d6bded3c1e..0b0a7fccdb00 100644 > > > --- a/arch/x86/kernel/reboot.c > > > +++ b/arch/x86/kernel/reboot.c > > > @@ -500,7 +500,7 @@ static int __init reboot_init(void) > > > */ > > > rv = dmi_check_system(reboot_dmi_table); > > > > > > - if (!rv && efi_reboot_required() && !efi_runtime_disabled()) > > > + if (!rv && efi_reboot_required() && > > > efi_enabled(EFI_RUNTIME_SERVICES)) > > > > Why is efi_reboot_required() set at all in that situation? > > > Hi Thomas, > > This platform uses HW Reduced ACPI ( > https://github.com/intel/cloud-hypervisor) but also supports direct > kernel boot without EFI. > > /* > * For most modern platforms the preferred method of powering off is > via > * ACPI. However, there are some that are known to require the use of > * EFI runtime services and for which ACPI does not work at all. > * > * Using EFI is a last resort, to be used only if no other option > * exists. > */ > bool efi_reboot_required(void) > { > if (!acpi_gbl_reduced_hardware) > return false; > > efi_reboot_quirk_mode = EFI_RESET_WARM; > return true; > } > > This is a hardware workaround that assumes that all ACPI HW reduced > platforms do not support ACPI reset: > > commit 44be28e9dd9880dca3e2cbf7a844f2114e67f2cb > Author: Matt Fleming <matt.flem...@intel.com> > Date: Fri Jun 13 12:39:55 2014 +0100 > > x86/reboot: Add EFI reboot quirk for ACPI Hardware Reduced flag > > It appears that the BayTrail-T class of hardware requires EFI in > order > to powerdown and reboot and no other reliable method exists. > > This quirk is generally applicable to all hardware that has the > ACPI > Hardware Reduced bit set, since usually ACPI would be the > preferred > method. > > Cc: Len Brown <len.br...@intel.com> > Cc: Mark Salter <msal...@redhat.com> > Cc: "Rafael J. Wysocki" <rafael.j.wyso...@intel.com> > Signed-off-by: Matt Fleming <matt.flem...@intel.com> > > I'm reluctant to change the behaviour of efi_reboot_required() as it > might break older hardware whereas checking if we have an EFI runtime > is safer. >
Hi Thomas, Any update on your thoughts on this patch? Rob
