From mboxrd@z Thu Jan 1 00:00:00 1970 From: david mosberger Date: Tue, 12 Jul 2005 18:23:41 +0000 Subject: Re: [PATCH] enable to read region 5 from /dev/kmem Message-Id: List-Id: References: <42C501CD.4010907@jp.fujitsu.com> In-Reply-To: <42C501CD.4010907@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On 7/12/05, Luck, Tony wrote: > This is better. But allowing access to region 6 through > /dev/kmem will open up a whole new set of problems. If the > user does an uncacheable read through region 6 from a memory > address that is mapped cacheably in region 7, then the > processor may machine check [SDM 4.4.1, page 2:64, last > paragraph: "It is recommended that the processor report a > Machine Check abort if the following memory attribute aliasing > is detected: * cache-hit on an uncacheable page"] > > So I think we should disallow access to region 6. /dev/[k]mem should use the EFI memory attributes to determine accessibility. This is being done to some degree already (well, I didn't check the current code, but it's supposed to be there). --david