66 lines
2.4 KiB
Diff
66 lines
2.4 KiB
Diff
From: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
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Date: Thu, 14 Feb 2013 09:12:52 +0900
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Subject: efi: Clear EFI_RUNTIME_SERVICES rather than EFI_BOOT by "noefi" boot
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parameter
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commit 1de63d60cd5b0d33a812efa455d5933bf1564a51 upstream.
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There was a serious problem in samsung-laptop that its platform driver is
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designed to run under BIOS and running under EFI can cause the machine to
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become bricked or can cause Machine Check Exceptions.
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Discussion about this problem:
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https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557
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https://bugzilla.kernel.org/show_bug.cgi?id=47121
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The patches to fix this problem:
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efi: Make 'efi_enabled' a function to query EFI facilities
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83e68189745ad931c2afd45d8ee3303929233e7f
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samsung-laptop: Disable on EFI hardware
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e0094244e41c4d0c7ad69920681972fc45d8ce34
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Unfortunately this problem comes back again if users specify "noefi" option.
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This parameter clears EFI_BOOT and that driver continues to run even if running
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under EFI. Refer to the document, this parameter should clear
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EFI_RUNTIME_SERVICES instead.
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Documentation/kernel-parameters.txt:
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===============================================================================
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...
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noefi [X86] Disable EFI runtime services support.
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...
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===============================================================================
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Documentation/x86/x86_64/uefi.txt:
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===============================================================================
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...
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- If some or all EFI runtime services don't work, you can try following
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kernel command line parameters to turn off some or all EFI runtime
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services.
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noefi turn off all EFI runtime services
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...
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===============================================================================
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Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
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Link: http://lkml.kernel.org/r/511C2C04.2070108@jp.fujitsu.com
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Cc: Matt Fleming <matt.fleming@intel.com>
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Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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---
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arch/x86/platform/efi/efi.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
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index 77cf009..928bf83 100644
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--- a/arch/x86/platform/efi/efi.c
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+++ b/arch/x86/platform/efi/efi.c
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@@ -87,7 +87,7 @@ EXPORT_SYMBOL(efi_enabled);
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static int __init setup_noefi(char *arg)
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{
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- clear_bit(EFI_BOOT, &x86_efi_facility);
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+ clear_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);
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return 0;
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}
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early_param("noefi", setup_noefi);
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