From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-x242.google.com (mail-pa0-x242.google.com [IPv6:2607:f8b0:400e:c03::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rlzwN46NXzDqpk for ; Fri, 8 Jul 2016 13:08:52 +1000 (AEST) Received: by mail-pa0-x242.google.com with SMTP id us13so3283614pab.1 for ; Thu, 07 Jul 2016 20:08:52 -0700 (PDT) Subject: Re: [RFC/PATCH 3/4] powerpc/64/kexec: Copy image with MMU off when possible To: Benjamin Herrenschmidt , linuxppc-dev@lists.ozlabs.org References: <1467779707.13965.103.camel@kernel.crashing.org> Cc: Anton Blanchard , "Aneesh Kumar K.V" From: Balbir Singh Message-ID: Date: Fri, 8 Jul 2016 13:08:44 +1000 MIME-Version: 1.0 In-Reply-To: <1467779707.13965.103.camel@kernel.crashing.org> Content-Type: text/plain; charset=utf-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 06/07/16 14:35, Benjamin Herrenschmidt wrote: > Currently we turn the MMU off after copying the image, and we make > sure there is no overlap between the hash table and the target pages > in that case. > > That doesn't work for Radix however. In that case, the page tables > are scattered and we can't really enforce that the target of the > image isn't overlapping one of them. > > So instead, let's turn the MMU off before copying the image in radix > mode. Thankfully, in radix mode, even under a hypervisor, we know we > don't have the same kind of RMA limitations that hash mode has. > > While at it, also turn the MMU off early when using hash in non-LPAR > mode, that way we can get rid of the collision check completely. > > Signed-off-by: Benjamin Herrenschmidt > --- > Currently only compile tested This makes sense Acked-by: Balbir Singh