From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:42561) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RoKey-0003DM-Kj for qemu-devel@nongnu.org; Fri, 20 Jan 2012 15:02:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RoKes-0002qA-WA for qemu-devel@nongnu.org; Fri, 20 Jan 2012 15:02:04 -0500 Message-ID: <4F19C82F.60203@freescale.com> Date: Fri, 20 Jan 2012 14:01:51 -0600 From: Scott Wood MIME-Version: 1.0 References: <4F192141.6030107@suse.de> <1327065698-7538-1-git-send-email-agraf@suse.de> In-Reply-To: <1327065698-7538-1-git-send-email-agraf@suse.de> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] PPC: booke206: Check for min/max TLB entry size List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: qemu-ppc@nongnu.org, qemu-devel Developers , =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= On 01/20/2012 07:21 AM, Alexander Graf wrote: > When setting a TLB entry, we need to check if the TLB we're putting it in > actually supports the given size. According to the 2.06 PowerPC ISA, a > value that's out of range results in the minimum page size for the TLB > to be used. The ISA says, "If the page size specified by MAS1TSIZE is not supported by the specified array, the tlbwe may be performed as if TSIZE were some imple- mentation-dependent value, or an Illegal Instruction exception occurs." In practice, what this means on e500 is that TLB0 (which only supports one page size) ignores TSIZE. I'm not sure what happens when you write an entry to TLB1 with an invalid TSIZE. > + /* XXX only applies for MAV 1.0 */ > + size_tlb = (tlb->mas1 & MAS1_TSIZE_MASK) >> (MAS1_TSIZE_SHIFT + 1); > + size_min = (tlbncfg & TLBnCFG_MINSIZE) >> TLBnCFG_MINSIZE_SHIFT; > + size_max = (tlbncfg & TLBnCFG_MAXSIZE) >> TLBnCFG_MAXSIZE_SHIFT; > + if ((size_tlb > size_max) || (size_tlb < size_min)) { > + /* set to min size */ > + tlb->mas1 &= ~MAS1_TSIZE_MASK; > + tlb->mas1 |= size_min << (MAS1_TSIZE_SHIFT + 1); > + } You could just implement a bitmap now, which will work for MAV 2.0 as well. Especially since we're using the MAV 2.0 definition of tsize already, so min/max isn't an accurate way to describe what we support. -Scott