From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Howells <dhowells@redhat.com>
Subject: Re: [PATCH 6/6] efi: Add EFI_SECURE_BOOT bit [ver #2]
Date: Wed, 23 Nov 2016 10:07:21 +0000
Message-ID: <3710.1479895641@warthog.procyon.org.uk>
References: <20161123092735.GA2071@wunner.de> <147986054870.13790.8640536414645705863.stgit@warthog.procyon.org.uk> <147986059202.13790.3471243422582131819.stgit@warthog.procyon.org.uk>
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To: Lukas Wunner <lukas@wunner.de>
Cc: dhowells@redhat.com, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, Josh Boyer <jwboyer@fedoraproject.org>, keyrings@vger.kernel.org
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Lukas Wunner <lukas@wunner.de> wrote:

> > +#ifdef CONFIG_EFI
> > +	if (boot_params.secure_boot) {
> > +		set_bit(EFI_SECURE_BOOT, &efi.flags);
> > +		pr_info("Secure boot enabled\n");
> > +	}
> > +#endif
> > +
> 
> Section 20 of Documentation/CodingStyle recommends IS_ENABLED()
> instead of #ifdef.

The problem is this:

	arch/x86/include/asm/bitops.h:75: undefined reference to `efi'

To quote section 20: "... Thus, you still have to use an #ifdef if the code
inside the block references symbols that will not exist if the condition is
not met."

> Also, CONFIG_EFI_STUB might be more apt than CONFIG_EFI.

Other stuff in the same function is contingent on CONFIG_EFI.  EFI_STUB is to
do with how the thing can be booted, I think - not whether EFI support is
enabled.

David