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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1FB1C433E7 for ; Mon, 12 Oct 2020 21:35:50 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4906320797 for ; Mon, 12 Oct 2020 21:35:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4906320797 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=m5p.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.6034.15797 (Exim 4.92) (envelope-from ) id 1kS5TO-0007U7-0q; Mon, 12 Oct 2020 21:35:14 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 6034.15797; Mon, 12 Oct 2020 21:35:13 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kS5TN-0007U0-U7; Mon, 12 Oct 2020 21:35:13 +0000 Received: by outflank-mailman (input) for mailman id 6034; Mon, 12 Oct 2020 21:35:12 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kS5TM-0007Tv-KN for xen-devel@lists.xenproject.org; Mon, 12 Oct 2020 21:35:12 +0000 Received: from mailhost.m5p.com (unknown [74.104.188.4]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 44a200bb-fba6-4669-ae4e-e0c31806915c; Mon, 12 Oct 2020 21:35:11 +0000 (UTC) Received: from m5p.com (mailhost.m5p.com [IPv6:2001:470:1f07:15ff:0:0:0:f7]) by mailhost.m5p.com (8.15.2/8.15.2) with ESMTPS id 09CLYqhX089433 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 12 Oct 2020 17:34:58 -0400 (EDT) (envelope-from ehem@m5p.com) Received: (from ehem@localhost) by m5p.com (8.15.2/8.15.2/Submit) id 09CLYpGX089432; Mon, 12 Oct 2020 14:34:51 -0700 (PDT) (envelope-from ehem) Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kS5TM-0007Tv-KN for xen-devel@lists.xenproject.org; Mon, 12 Oct 2020 21:35:12 +0000 X-Inumbo-ID: 44a200bb-fba6-4669-ae4e-e0c31806915c Received: from mailhost.m5p.com (unknown [74.104.188.4]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 44a200bb-fba6-4669-ae4e-e0c31806915c; Mon, 12 Oct 2020 21:35:11 +0000 (UTC) Received: from m5p.com (mailhost.m5p.com [IPv6:2001:470:1f07:15ff:0:0:0:f7]) by mailhost.m5p.com (8.15.2/8.15.2) with ESMTPS id 09CLYqhX089433 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 12 Oct 2020 17:34:58 -0400 (EDT) (envelope-from ehem@m5p.com) Received: (from ehem@localhost) by m5p.com (8.15.2/8.15.2/Submit) id 09CLYpGX089432; Mon, 12 Oct 2020 14:34:51 -0700 (PDT) (envelope-from ehem) Date: Mon, 12 Oct 2020 14:34:51 -0700 From: Elliott Mitchell To: Stefano Stabellini Cc: Julien Grall , Masami Hiramatsu , xen-devel@lists.xenproject.org, Alex Benn??e , bertrand.marquis@arm.com, andre.przywara@arm.com, Julien Grall , Volodymyr Babchuk Subject: Re: [PATCH 0/4] xen/arm: Unbreak ACPI Message-ID: <20201012213451.GA89158@mattapan.m5p.com> References: <20200926205542.9261-1-julien@xen.org> <1a7b5a14-7d21-b067-a80b-27d963f9798a@xen.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Oct 12, 2020 at 12:02:14PM -0700, Stefano Stabellini wrote: > On Sat, 10 Oct 2020, Julien Grall wrote: > > Therefore, I think the code should not try to find the STAO. Instead, it > > should check whether the SPCR table is present. > > Yes, that makes sense, but that brings me to the next question. > > SPCR seems to be required by SBBR, however, Masami wrote that he could > boot on a system without SPCR, which gets me very confused for two > reasons: > > 1) Why there is no SPCR? Isn't it supposed to be mandatory? Is it > because there no UART on Masami's system? I'm on different hardware, but some folks have setup Tianocore for it. According to Documentation/arm64/acpi_object_usage.rst, "Required: DSDT, FADT, GTDT, MADT, MCFG, RSDP, SPCR, XSDT". Yet when booting a Linux kernel directly on the hardware it lists APIC, BGRT, CSRT, DSDT, DBG2, FACP, GTDT, PPTT, RSDP, and XSDT. I don't know whether Linux's ACPI code omits mention of some required tables and merely panics if they're absent. Yet I'm speculating the list of required tables has shrunk, SPCR is no longer required, and the documentation is out of date. Perhaps SPCR was required in early Linux ACPI implementations, but more recent ones removed that requirement? > 2) If there is no SPCR, how did Masami manage to boot Xen? > I take without any serial output? Just with the framebuffer? On my board the provided tables are sufficient to let Linux identify ttyAMA0. Linux's efifb driver finds the framebuffer and apparently has it usable. -- (\___(\___(\______ --=> 8-) EHM <=-- ______/)___/)___/) \BS ( | ehem+sigmsg@m5p.com PGP 87145445 | ) / \_CS\ | _____ -O #include O- _____ | / _/ 8A19\___\_|_/58D2 7E3D DDF4 7BA6 <-PGP-> 41D1 B375 37D0 8714\_|_/___/5445