From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bryan O'Donoghue Subject: Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000 Date: Thu, 08 Jan 2015 12:10:47 +0000 Message-ID: <54AE73C7.90009@nexus-software.ie> References: <1419873783-5161-1-git-send-email-pure.logic@nexus-software.ie> <1419873783-5161-2-git-send-email-pure.logic@nexus-software.ie> <20150106073634.GB59754@vmdeb7> <54ABE67B.1070706@nexus-software.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: "Ong, Boon Leong" , Darren Hart Cc: "tglx@linutronix.de" , "mingo@redhat.com" , "hpa@zytor.com" , "x86@kernel.org" , "platform-driver-x86@vger.kernel.org" , "linux-kernel@vger.kernel.org" List-Id: platform-driver-x86.vger.kernel.org On 07/01/15 23:45, Ong, Boon Leong wrote: >> Since BIOS and grub code both use 0x00000000 as the 'off' address I think it >> makes sense for the kernel to continue to use that address. > > Just add on top of what Daren mentioned in another mail, based on the Quark document, > the base address can start from zero. Say lo=0, hi=0, and WM & RM may be changed from default value, > 1st 1KiB will be marked as IMR. It seems to me that there is no good way to test if an IMR is 'occupied' and/or 'enabled' > since enable-bit is not available. But, what is benefit of testing against lo=0 & hi=0? The logic to calculate size will work under > lo=0 & hi=0 anway. Hi Boon Leong. I think it does make sense to add a check for rmask and wmask in the 'access all' state when determining if an IMR is enabled on X1000 or not. >> My own view is that it's not really desirable and easier to debug IMRs >> generally on a platform if overlaps aren't allowed. > I do agree on the benefit listed above. Perhaps, you can add explanation here > to mention the design decision. Will do.