From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D0652C433EF for ; Sun, 13 Feb 2022 23:27:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238784AbiBMX1G (ORCPT ); Sun, 13 Feb 2022 18:27:06 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:51208 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238771AbiBMX1F (ORCPT ); Sun, 13 Feb 2022 18:27:05 -0500 X-Greylist: delayed 171 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sun, 13 Feb 2022 15:26:59 PST Received: from relay9-d.mail.gandi.net (relay9-d.mail.gandi.net [217.70.183.199]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13E585133A; Sun, 13 Feb 2022 15:26:58 -0800 (PST) Received: (Authenticated sender: ash@heyquark.com) by mail.gandi.net (Postfix) with ESMTPSA id 9A7ADFF802; Sun, 13 Feb 2022 23:26:51 +0000 (UTC) Message-ID: <992dccb9-590a-c7b7-146f-d134fb399f7e@heyquark.com> Date: Mon, 14 Feb 2022 10:26:47 +1100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [RFC] Upstreaming Linux for Nintendo Wii U Content-Language: en-US To: Christophe Leroy , Michael Ellerman , "benh@kernel.crashing.org" , "paulus@samba.org" Cc: "linkmauve@linkmauve.fr" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "amd-gfx@lists.freedesktop.org" , "linuxppc-dev@lists.ozlabs.org" , "j.ne@posteo.net" References: <0020d47c-0e23-822c-33f5-ccb7ea4c1072@heyquark.com> <87ee49sktb.fsf@mpe.ellerman.id.au> <41c696de-0e04-61e1-610c-73e9440c5c19@csgroup.eu> From: Ash Logan In-Reply-To: <41c696de-0e04-61e1-610c-73e9440c5c19@csgroup.eu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Christophe, On 12/2/22 00:11, Christophe Leroy wrote: > Hi Ash, > > Le 11/02/2022 à 12:29, Michael Ellerman a écrit : >> Ash Logan writes: >>> - Like the Wii before it, the Wii U has a small amount of RAM at address >>> zero, a gap, then a large amount of RAM at a higher address. Instead of >>> the "map everything and reserve the gap" approach of the Wii, we loop >>> over each memblock and map only true RAM[9]. This seems to work, but as >>> far as I can tell is unique amongst powerpc32 platforms, so it's worth >>> pointing out. (Note: I've been told this doesn't work anymore after some >>> KUAP changes[10], so this point might be moot; haven't investigated) >> >> We'd need more detail on that I guess. Currently all the 32-bit >> platforms use the flat memory model, which assumes RAM is a single >> contiguous block. Though that doesn't mean it all has to be used or >> mapped, like the Wii does. To properly support your layout you should be >> using sparsemem, but it's possible that's more trouble than it's worth, >> I'm not sure. How far apart are the low and high blocks of RAM, and what >> are their sizes? > > Can you provide details on what's happening with KUAP changes ? > > You are pointing to series https://lkml.org/lkml/2021/6/3/204 > > Does it work when CONFIG_PPC_KUAP is not selected or doesn't it work > either ? > > Are you able to bisect which commit of that series is the culprit ? Emmanuel told me about this during their work on 5.13 which I wasn't involved in, and now can't remember any of the details, so I guess I don't actually have any more information. I'm working on getting a baseline setup for 5.15 (just udbg and the like), so if there is an issue I should soon find out about it and will get back to you. > Thanks > Christophe Thanks, Ash