From mboxrd@z Thu Jan  1 00:00:00 1970
From: Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>
Subject: Re: [PATCH -v2] EFI: Runtime services virtual mapping
Date: Wed, 25 Sep 2013 07:47:03 +0200
Message-ID: <20130925054703.GA12962@nazgul.tnic>
References: <e39e1065bddc2afee2cb6eed957e3ba8.squirrel@www.skyhub.de>
 <52422A6A.8080305@zytor.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Return-path: <linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Content-Disposition: inline
In-Reply-To: <52422A6A.8080305-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
To: "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
Cc: Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, X86 ML <x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Borislav Petkov <bp-l3A5Bk7waGM@public.gmane.org>, Matt Fleming <matt-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>, Matthew Garrett <mjg59-1xO5oi07KQx4cg9Nei1l7Q@public.gmane.org>, James Bottomley <james.bottomley-JuX6DAaQMKPCXq6kfMZ53/egYHeGw8Jk@public.gmane.org>, Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-Id: linux-efi@vger.kernel.org

On Tue, Sep 24, 2013 at 05:12:26PM -0700, H. Peter Anvin wrote:
> I am starting to think that we really should explicitly pass along the
> EFI mappings to the secondary kernel.  This will also help if we have to
> change the algorithm in a future kernel.

That would be the most flexible solution, sure.

> The most logical way to do this is to define a new setup_data type and
> pass the entire set of physical-to-virtual mappings that way.
> 
> For example:
> 
> struct efi_mapping {
> 	u64 va;			/* Virtual start address */
> 	u64 pa;			/* Physical start address */
> 	u64 len;		/* Length in bytes */
> 	u64 type;		/* Mapping type */
> 	u64 reserved[3];	/* Reserved, must be zero */
> };
> 
> Adding some reserved fields seems like a prudent precaution;

... and making checking they're zeroed out initially so that I can use
them in the future, if needed :)

> the map shouldn't be all that large anyway.

Yeah, let me look at it in more detail when I get back - it shouldn't be
that hard to do.

Thanks.