Date: Tue, 15 May 2012 15:00:15 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Gleb Natapov <gleb@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>, LKML <linux-kernel@vger.kernel.org>,
        "H. Peter Anvin" <hpa@linux.intel.com>
Subject: Re: [PATCH] EDD: Check for correct EDD 3.0 length
Message-ID: <20120515150015.5bf17aea@pyramind.ukuu.org.uk>
In-Reply-To: <20120515115917.GK32036@redhat.com>
References: <1337079889-62380-1-git-send-email-hare@suse.de>
	<20120515111255.GJ32036@redhat.com>
	<4FB23C09.7060300@suse.de>
	<20120515115917.GK32036@redhat.com>
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> T13 EDD4.0 actually supply enough information to link edd entry to actual
> device (another spec does not), I do not see support for other spec to
> be important, but you are welcome to write support for it if you need
> it. The only way I see to check what spec edd info corresponds to is to
> calculate checksum according to both specs and see which one succeeds.

I also think you are confused on this: EDD 3.0 provides enough
information to link most types of hardware to the device. It provides the
PCI or Legacy path to the interface and the device LUN, or for 1394 etc
the WWID which can be used to cross match. It doesn't address port
multipliers.

EDD 1.1 provides sufficient information for old systems too via the FDPT
as they only have to deal with MFM/IDE/ATA controllers at the legacy
mappings and these are described by the FDPT.

Prior to that it gets a bit more interesting and you have to go poking in
BIOS magic and have the required spellbooks to hand. However right back
to the original 386 era PCs the data is available.

Alan
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