linux-kernel - Re: [PATCH] x86: efi: Turn off efi_enabled after setup on mixed fw/kernel

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Message-ID: <50320DBD.5080507@canonical.com>
Date:	Mon, 20 Aug 2012 12:13:17 +0200
From:	Maarten Lankhorst <maarten.lankhorst@...onical.com>
To:	Olof Johansson <olof@...om.net>
CC:	hpa@...or.com, linux-kernel@...r.kernel.org, mk@....su,
	Marko Kohtala <marko.kohtala@...il.com>,
	Matt Fleming <matt.fleming@...el.com>,
	Matthew Garrett <mjg@...hat.com>
Subject: Re: [PATCH] x86: efi: Turn off efi_enabled after setup on mixed fw/kernel

Hey,

Op 19-08-12 23:48, Olof Johansson schreef:
> When 32-bit EFI is used with 64-bit kernel (or vice versa), turn off
> efi_enabled once setup is done. Beyond setup, it is normally used to
> determine if runtime services are available and we will have none.
>
> This will resolve issues stemming from efivars modprobe panicking on a
> 32/64-bit setup, as well as some reboot issues on similar setups.
>
> Signed-off-by: Olof Johansson <olof@...om.net>
> Cc: stable@...nel.org # 3.4 and 3.5
> Cc: Matt Fleming <matt.fleming@...el.com>
> Cc: Matthew Garrett <mjg@...hat.com>
> ---
>  arch/x86/kernel/setup.c     | 11 +++++++++++
>  arch/x86/platform/efi/efi.c | 14 ++++++++------
>  2 files changed, 19 insertions(+), 6 deletions(-)
> <snip>
>  
> +static inline bool efi_is_native(void)
> +{
> +	return !(IS_ENABLED(CONFIG_X86_64) ^ efi_64bit);
> +}
>
Isn't this just a more complicated way of writing
IS_ENABLED(CONFIG_X86_64) == efi_64bit ?

Also moving the assignment to efi_init will make it no longer call
efi_reserve_boot_services, I don't know if that is intentional or not,
but something to consider at least since it's a behavioral change.

>From a quick glance with some grepping, efi reboot and efifb will
also no longer work, is that intentional?

~Maarten

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