Commit 1de63d60 authored by Satoru Takeuchi's avatar Satoru Takeuchi Committed by H. Peter Anvin
Browse files

efi: Clear EFI_RUNTIME_SERVICES rather than EFI_BOOT by "noefi" boot parameter

There was a serious problem in samsung-laptop that its platform driver is
designed to run under BIOS and running under EFI can cause the machine to
become bricked or can cause Machine Check Exceptions.

    Discussion about this problem:
    https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557
    https://bugzilla.kernel.org/show_bug.cgi?id=47121

    The patches to fix this problem:
    efi: Make 'efi_enabled' a function to query EFI facilities
    83e68189

    samsung-laptop: Disable on EFI hardware
    e0094244



Unfortunately this problem comes back again if users specify "noefi" option.
This parameter clears EFI_BOOT and that driver continues to run even if running
under EFI. Refer to the document, this parameter should clear
EFI_RUNTIME_SERVICES instead.

Documentation/kernel-parameters.txt:
===============================================================================
...
	noefi		[X86] Disable EFI runtime services support.
...
===============================================================================

Documentation/x86/x86_64/uefi.txt:
===============================================================================
...
- If some or all EFI runtime services don't work, you can try following
  kernel command line parameters to turn off some or all EFI runtime
  services.
	noefi		turn off all EFI runtime services
...
===============================================================================
Signed-off-by: default avatarSatoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Link: http://lkml.kernel.org/r/511C2C04.2070108@jp.fujitsu.com


Cc: Matt Fleming <matt.fleming@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 323a72d8
......@@ -87,7 +87,7 @@ EXPORT_SYMBOL(efi_enabled);
static int __init setup_noefi(char *arg)
{
clear_bit(EFI_BOOT, &x86_efi_facility);
clear_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);
return 0;
}
early_param("noefi", setup_noefi);
......
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