From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-io0-x242.google.com ([2607:f8b0:4001:c06::242]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1fMGE9-0003Bm-PL for barebox@lists.infradead.org; Fri, 25 May 2018 17:10:07 +0000 Received: by mail-io0-x242.google.com with SMTP id d73-v6so7167044iog.3 for ; Fri, 25 May 2018 10:09:54 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20180525090124.wchev5lakkiny2gr@pengutronix.de> References: <20180523051012.26148-1-andrew.smirnov@gmail.com> <20180523084341.i5edq2nznd7spbi3@pengutronix.de> <20180525090124.wchev5lakkiny2gr@pengutronix.de> From: Andrey Smirnov Date: Fri, 25 May 2018 10:09:52 -0700 Message-ID: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [RFC] ARM: mmu: Do not try to pick early TTB up To: Sascha Hauer Cc: Barebox List On Fri, May 25, 2018 at 2:01 AM, Sascha Hauer wrote: > On Thu, May 24, 2018 at 08:14:40PM -0700, Andrey Smirnov wrote: >> On Wed, May 23, 2018 at 1:43 AM, Sascha Hauer wrote: >> > On Tue, May 22, 2018 at 10:10:12PM -0700, Andrey Smirnov wrote: >> >> The call to create_flat_mapping() in mmu.c will change both memory >> >> type and shareability of all RAM in use by barebox while MMU is on >> >> when done in conjunction with CONFIG_MMU_EARLY. >> > >> > I notice that with MMU_EARLY enabled we call create_flat_mapping() >> > twice, once in the early MMU code and once when setting up the MMU for >> > real. In between we remap the the SDRAM cached which then is reverted >> > during the second call to create_flat_mapping(). >> > >> > This seems unnecessary. Does the following help you? >> >> Yeah, this, disabling MMU before or having a tlb_invalidate() after >> all seem to help. Your patch works fine, but it has a slight weirdness >> in my case because early MMU code would mark OCRAM as cached and >> regular MMU code wouldn't undo it without the call to >> create_flat_mapping(), so I'd end up with slightly different memory >> configuration depending on if EARLY_MMU is enabled or not. Other than >> that it should work fine. >> >> The main reason I chose to go "disable MMU" route is because that >> follows what ARMv8 MMU code does, but I am perfectly happy with either >> solution. > > Disabling the MMU probably has a performance impact (I would have to > remeasure, maybe this is not true at all), that's why I would prefer > keeping it enabled. > OK, sure. Where do we go from here? Do you want to just take your patch or should I update mine, with its War And Peace of a commit message, and incorporate what you proposed? Thanks, Andrey Smirnov _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox