linux-kernel - Re: [PATCH v15 07/16] arm64: add image head flag definitions

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Message-ID: <20181009150404.cqpkmi2wumututwa@lakrids.cambridge.arm.com>
Date:   Tue, 9 Oct 2018 16:04:05 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     AKASHI Takahiro <takahiro.akashi@...aro.org>,
        catalin.marinas@....com, will.deacon@....com, dhowells@...hat.com,
        vgoyal@...hat.com, herbert@...dor.apana.org.au,
        davem@...emloft.net, dyoung@...hat.com, bhe@...hat.com,
        arnd@...db.de, schwidefsky@...ibm.com, heiko.carstens@...ibm.com,
        prudo@...ux.ibm.com, ard.biesheuvel@...aro.org,
        james.morse@....com, bhsharma@...hat.com,
        kexec@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v15 07/16] arm64: add image head flag definitions

On Tue, Oct 02, 2018 at 04:59:40PM +0900, AKASHI Takahiro wrote:
> Hi Mark,
> 
> On Mon, Oct 01, 2018 at 01:52:26PM +0100, Mark Rutland wrote:
> > On Fri, Sep 28, 2018 at 03:48:32PM +0900, AKASHI Takahiro wrote:
> > > Those image head's flags will be used later by kexec_file loader.
> > > 
> > > Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
> > > Cc: Catalin Marinas <catalin.marinas@....com>
> > > Cc: Will Deacon <will.deacon@....com>
> > > Acked-by: James Morse <james.morse@....com>
> > > ---
> > >  arch/arm64/include/asm/boot.h | 15 +++++++++++++++
> > >  arch/arm64/kernel/head.S      |  2 +-
> > >  2 files changed, 16 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/arm64/include/asm/boot.h b/arch/arm64/include/asm/boot.h
> > > index 355e552a9175..0bab7eed3012 100644
> > > --- a/arch/arm64/include/asm/boot.h
> > > +++ b/arch/arm64/include/asm/boot.h
> > > @@ -5,6 +5,21 @@
> > >  
> > >  #include <asm/sizes.h>
> > >  
> > > +#define ARM64_MAGIC		"ARM\x64"
> > > +
> > > +#define HEAD_FLAG_BE_SHIFT		0
> > > +#define HEAD_FLAG_PAGE_SIZE_SHIFT	1
> > > +#define HEAD_FLAG_BE_MASK		0x1
> > > +#define HEAD_FLAG_PAGE_SIZE_MASK	0x3
> > > +
> > > +#define HEAD_FLAG_BE			1
> > 
> > These already exist in some form in arch/arm64/kernel/image.h; can we
> > please factor those out rather than duplicating them?
> 
> Sure.
> 
> > I'd be happy if you'd update image.h to use the new HEAD_FLAG_* names,
> > and removed the old definitions.
> 
> I want to make sure two things;
> 
> 1. Do you assume all the existing __HEAD_FLAG_xyz's NOT be renamed
>    (say, to HEAD_FLAG_xyz)?

I'm perfectly happy for them to be renamed, I just don't want duplicate
definitions.

Let's rename them to ARM64_IMAGE_FLAG_<foo>, and place them in a new
header, arch/arm64/include/asm/image.h, which arch/arm64/kernel/image.h
can include and make use of.

> 
> 2. Do you mind removing this check in image.h?
>    (we also need to manage 'CONFIG_EFI' part of image.h.)

What exactly do we need from that? AFAICT that's all linker script
stuff that shouldn't matter for kexec.

Thanks,
Mark.