From patchwork Wed Sep 6 12:05:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13375624 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3FB3EEB8FB6 for ; Wed, 6 Sep 2023 12:07:07 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qdrIZ-0004EH-4S; Wed, 06 Sep 2023 08:06:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qdrI3-0003te-L5 for qemu-devel@nongnu.org; Wed, 06 Sep 2023 08:05:50 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qdrHz-0006nb-CJ for qemu-devel@nongnu.org; Wed, 06 Sep 2023 08:05:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1694001942; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xjl+jwf6S6C7TTZrfneBrUP7JU1jXf7dtndXiCRb7qo=; b=VRi+f6FXIHcqXLyYMWPMbwh8yWVs87XL5ugnJcd+ynOlNO8DgtNWNMqpKg1FXLp5qZ7N/8 po6HcY4M/dPKXBtM26TaRvnRnE04HcEwwUZjPSVSDAspmFHoX3jQ4brDZ4utWcR7d7EBzB GyPiD+4tJdo9Kwdyk9x0kcc1xbMLEiU= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-86-ymTN0V9CMqKmtPgEjgqdPg-1; Wed, 06 Sep 2023 08:05:37 -0400 X-MC-Unique: ymTN0V9CMqKmtPgEjgqdPg-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4244A2812946; Wed, 6 Sep 2023 12:05:36 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.39.192.60]) by smtp.corp.redhat.com (Postfix) with ESMTP id 430DD493110; Wed, 6 Sep 2023 12:05:33 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Cc: David Hildenbrand , Paolo Bonzini , Peter Xu , Igor Mammedov , Thiner Logoer , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= , =?utf-8?q?Daniel_P_=2E_Berrang?= =?utf-8?q?=C3=A9?= , Stefan Hajnoczi , Elena Ufimtseva , Jagannathan Raman , "Michael S. Tsirkin" , Ani Sinha , Xiao Guangrong , Daniel Henrique Barboza , Greg Kurz , Eric Blake , Markus Armbruster , Eduardo Habkost Subject: [PATCH v4 08/11] docs: Don't mention "-mem-path" in multi-process.rst Date: Wed, 6 Sep 2023 14:05:00 +0200 Message-ID: <20230906120503.359863-9-david@redhat.com> In-Reply-To: <20230906120503.359863-1-david@redhat.com> References: <20230906120503.359863-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.133.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org "-mem-path" corresponds to "memory-backend-file,share=off" and, therefore, creates a private COW mapping of the file. For multi-proces QEMU, we need proper shared file-backed memory. Let's make that clearer. Signed-off-by: David Hildenbrand --- docs/devel/multi-process.rst | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/docs/devel/multi-process.rst b/docs/devel/multi-process.rst index e4801751f2..4ef539c0b0 100644 --- a/docs/devel/multi-process.rst +++ b/docs/devel/multi-process.rst @@ -409,8 +409,9 @@ the initial messages sent to the emulation process is a guest memory table. Each entry in this table consists of a file descriptor and size that the emulation process can ``mmap()`` to directly access guest memory, similar to ``vhost_user_set_mem_table()``. Note guest memory -must be backed by file descriptors, such as when QEMU is given the -*-mem-path* command line option. +must be backed by shared file-backed memory, for example, using +*-object memory-backend-file,share=on* and setting that memory backend +as RAM for the machine. IOMMU operations ^^^^^^^^^^^^^^^^