From patchwork Thu Apr 14 00:04:31 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Chamberlain X-Patchwork-Id: 8829691 Return-Path: X-Original-To: patchwork-linux-acpi@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 5D79DC0553 for ; Thu, 14 Apr 2016 00:05:04 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 66D7520382 for ; Thu, 14 Apr 2016 00:05:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2218420380 for ; Thu, 14 Apr 2016 00:05:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932099AbcDNAE5 (ORCPT ); Wed, 13 Apr 2016 20:04:57 -0400 Received: from mail.kernel.org ([198.145.29.136]:36335 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932256AbcDNAE4 (ORCPT ); Wed, 13 Apr 2016 20:04:56 -0400 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7DB3C20173; Thu, 14 Apr 2016 00:04:54 +0000 (UTC) Received: from garbanzo.do-not-panic.com (c-73-15-241-2.hsd1.ca.comcast.net [73.15.241.2]) (using TLSv1.2 with cipher AES128-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4F142201BB; Thu, 14 Apr 2016 00:04:52 +0000 (UTC) From: "Luis R. Rodriguez" To: bp@alien8.de, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, rusty@rustcorp.com.au Cc: x86@kernel.org, linux-kernel@vger.kernel.org, luto@amacapital.net, boris.ostrovsky@oracle.com, jgross@suse.com, david.vrabel@citrix.com, konrad.wilk@oracle.com, xen-devel@lists.xensource.com, lguest@lists.ozlabs.org, andriy.shevchenko@linux.intel.com, jlee@suse.com, glin@suse.com, matt@codeblueprint.co.uk, andrew.cooper3@citrix.com, rjw@rjwysocki.net, lenb@kernel.org, robert.moore@intel.com, lv.zheng@intel.com, toshi.kani@hp.com, linux-acpi@vger.kernel.org, kozerkov@parallels.com, josh@joshtriplett.org, bigeasy@linutronix.de, ffainelli@freebox.fr, george.dunlap@citrix.com, julien.grall@linaro.org, mbizon@freebox.fr, tiwai@suse.de, "Luis R. Rodriguez" Subject: [PATCH v6 01/16] x86/boot: enumerate documentation for the x86 hardware_subarch Date: Wed, 13 Apr 2016 17:04:31 -0700 Message-Id: <1460592286-300-2-git-send-email-mcgrof@kernel.org> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1460592286-300-1-git-send-email-mcgrof@kernel.org> References: <1460592286-300-1-git-send-email-mcgrof@kernel.org> X-Spam-Status: No, score=-7.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Although hardware_subarch has been in place since the x86 boot protocol 2.07 it hasn't been used much. Enumerate current possible values to avoid misuses and help with semantics later at boot time should this be used further. These enums should only ever be used by architecture x86 code, and all that code should be well contained and compartamentalized, clarify that as well. v4: updates documentation further -- be a bit more pedantic about annotating care and use of these guys. v5: Use s/SOC/SoC and also anntoate that both domU and dom0 are both currently supported through the PV boot path. v6: add big fat warning about how this is for legacy platforms only, as per Ingo's request Signed-off-by: Luis R. Rodriguez --- arch/x86/include/uapi/asm/bootparam.h | 41 ++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h index 329254373479..c18ce67495fa 100644 --- a/arch/x86/include/uapi/asm/bootparam.h +++ b/arch/x86/include/uapi/asm/bootparam.h @@ -157,7 +157,46 @@ struct boot_params { __u8 _pad9[276]; /* 0xeec */ } __attribute__((packed)); -enum { +/** + * enum x86_hardware_subarch - x86 hardware subarchitecture + * + * The x86 hardware_subarch and hardware_subarch_data were added as of the x86 + * boot protocol 2.07 to help distinguish and support custom x86 boot + * sequences. This enum represents accepted values for the x86 + * hardware_subarch. Custom x86 boot sequences (not X86_SUBARCH_PC) do not + * have or simply *cannot* make use of natural stubs like BIOS or EFI, the + * hardware_subarch can be used on the Linux entry path to revector to a + * subarchitecture stub when needed. This subarchitecture stub can be used to + * set up Linux boot parameters or for special care to account for nonstandard + * handling of page tables. + * + * These enums should only ever be used by x86 code, and the code that uses + * it should be well contained and compartamentalized. + * + * KVM and Xen HVM do not have a subarch as these are expected to follow + * standard x86 boot entries. If there is a genuine need for "hypervisor" type + * that should be considered separately in the future. Future guest types + * should seriously consider working with standard x86 boot stubs such as + * the BIOS or EFI boot stubs. + * + * WARNING: this enum is only used for legacy hacks, for platform features that + * are not easily enumerated or discoverable. You should not ever use + * this for new features. + * + * @X86_SUBARCH_PC: Should be used if the hardware is enumerable using standard + * PC mechanisms (PCI, ACPI) and doesn't need a special boot flow. + * @X86_SUBARCH_LGUEST: Used for x86 hypervisor demo, lguest + * @X86_SUBARCH_XEN: Used for Xen guest types which follow the PV boot path, + * which start at asm startup_xen() entry point and later jump to the C + * xen_start_kernel() entry point. Both domU and dom0 type of guests are + * currently supportd through this PV boot path. + * @X86_SUBARCH_INTEL_MID: Used for Intel MID (Mobile Internet Device) platform + * systems which do not have the PCI legacy interfaces. + * @X86_SUBARCH_CE4100: Used for Intel CE media processor (CE4100) SoC for + * for settop boxes and media devices, the use of a subarch for CE4100 + * is more of a hack... + */ +enum x86_hardware_subarch { X86_SUBARCH_PC = 0, X86_SUBARCH_LGUEST, X86_SUBARCH_XEN,