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

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Date:	Tue, 21 Aug 2012 15:39:00 +0100
From:	Matt Fleming <matt.fleming@...el.com>
To:	Olof Johansson <olof@...om.net>
Cc:	Maarten Lankhorst <maarten.lankhorst@...onical.com>, hpa@...or.com,
	linux-kernel@...r.kernel.org, mk@....su,
	Marko Kohtala <marko.kohtala@...il.com>,
	Matthew Garrett <mjg@...hat.com>,
	Peter Jones <pjones@...hat.com>
Subject: Re: [PATCH] x86: efi: Turn off efi_enabled after setup on mixed
 fw/kernel

On Mon, 2012-08-20 at 14:59 -0700, Olof Johansson wrote:
> > From a quick glance with some grepping, efi reboot and efifb will
> > also no longer work, is that intentional?
> 
> That's the very point of this patch, the EFI services won't work since
> there are no runtime services in this state, just boot time setup. If
> efi_enabled is left on, the reboot will panic.

But efifb should still work without EFI runtime services, no? I see this
in setup_arch(),

#ifdef CONFIG_VT                                                                
#if defined(CONFIG_VGA_CONSOLE)                                                 
        if (!efi_enabled || (efi_mem_type(0xa0000) != EFI_CONVENTIONAL_MEMORY)) 
                conswitchp = &vga_con;                                          
#elif defined(CONFIG_DUMMY_CONSOLE)                                             
        conswitchp = &dummy_con;                                                
#endif                                                                          
#endif                                   

but efi_enabled check looks bogus now that efi_enabled has come to mean
"EFI services available?". If we've been passed the dimensions of the
EFI framebuffer I'm unaware of a reason we can't use it.

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