Hi Matt,
(2013/02/21 5:36), Matt Fleming wrote:
> From: Matt Fleming <matt.fleming@xxxxxxxxx>
>
> commit 1de63d60cd5b ("efi: Clear EFI_RUNTIME_SERVICES rather than
> EFI_BOOT by "noefi" boot parameter") attempted to make "noefi" true to
> its documentation and disable EFI runtime services to prevent the
> bricking bug described in commit e0094244e41c ("samsung-laptop:
> Disable on EFI hardware"). However, it's not possible to clear
> EFI_RUNTIME_SERVICES from an early param function because
> EFI_RUNTIME_SERVICES is set in efi_init() *after* parse_early_param().
>
> This resulted in "noefi" effectively becoming a no-op and no longer
> providing users with a way to disable EFI, which is bad for those
> users that have buggy machines.
Sorry, my patch was imperfect. This patch looks good to me.
Reviewed-by: Satoru Takeuchi <takeuchi_satoru@xxxxxxxxxxxxxx>
Thanks,
Satoru
>
> Reported-by: Walt Nelson Jr <walt0924@xxxxxxxxx>
> Cc: Satoru Takeuchi <takeuchi_satoru@xxxxxxxxxxxxxx>
> Cc: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
> ---
> arch/x86/platform/efi/efi.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index 928bf83..e2cd38f 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -85,9 +85,10 @@ int efi_enabled(int facility)
> }
> EXPORT_SYMBOL(efi_enabled);
>
> +static bool disable_runtime = false;
> static int __init setup_noefi(char *arg)
> {
> - clear_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);
> + disable_runtime = true;
> return 0;
> }
> early_param("noefi", setup_noefi);
> @@ -734,7 +735,7 @@ void __init efi_init(void)
> if (!efi_is_native())
> pr_info("No EFI runtime due to 32/64-bit mismatch with kernel\n");
> else {
> - if (efi_runtime_init())
> + if (disable_runtime || efi_runtime_init())
> return;
> set_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);
> }
>
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