From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zoltan Menyhart Date: Thu, 23 Oct 2003 09:31:53 +0000 Subject: Re: [RFC] prevent "dd if=/dev/mem" crash Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Some machines may require special memory zones, e.g. for ia64 architectures you need to keep the "minimal state save" area for the Processor Abstraction Layer in un-cached memory. If you read the memory "in the usual way" then you access the memory through the HW caches. The ia64 architecture forbids to have both cached and un-cached access to the same memory location (by any of the CPUs, DMAs), otherwise you create a cache paradox => machine check. Think twice before even trying a "dd if=/dev/mem"... Zoltan Menyhart