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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 AA2F2C77B7A for ; Thu, 1 Jun 2023 02:15:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ShnyFxTZzyRnjl0I+pQZ0UJ+1To3LGuMbnWI+Ro9CTI=; b=m2/xrDKCEw57ny +bP1kA0HOKm98j8wNyS4teuAZ2eQQP15UqNfmZmXgv4PQCgD9fGGsssc7AJkRjnARbEgSKRaPKNne OOO4debL2yzy66J9IKFA5omZlTnLnzQH3YlZlYirigfreGE7aTauvEkdxpvBlI42j2lZbGoocTEbf pglEYoSYKb34EAMeD6sYn0Ceyxez+52yLOds2+P0j63Fu4QrijuKhqV0IAS/1i0S7qFtLnCcLkSam ny0hBr83EKETYowmtUQXvX1fPjMSth9EwWhj38FmsC4EREZTbBW1v8FCzAnQX0pad1koQTa+cT9AF HNtA3WJj/K9+y3xh1WGw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q4Xqn-001hNg-1C; Thu, 01 Jun 2023 02:15:41 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q4Xqj-001hMd-20 for kexec@lists.infradead.org; Thu, 01 Jun 2023 02:15:38 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685585736; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=07+CNsneIoVDruoAxJKFo1HiC0RGLoxI/2tCL7nWfWk=; b=gnhmSa+CuIYJbdeQ/pak3Wh6rCxqSAbHRbRcroFadN0tiLhJFE9Ndanisw17r9W7mAJudp AipLNuz4S+PsVx7asoA9BAaAk6BcoZLk8KimDwvtfRdNBHMi+7Oc8DjnHTfOvzfWunVw5o e2qynsTyDfDAvCapol6DCPDaqBtj370= Received: from mimecast-mx02.redhat.com (mx3-rdu2.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-455-0E5pcOXtMcCkmyYhinzlRw-1; Wed, 31 May 2023 22:15:29 -0400 X-MC-Unique: 0E5pcOXtMcCkmyYhinzlRw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B24BD380450F; Thu, 1 Jun 2023 02:15:27 +0000 (UTC) Received: from localhost (ovpn-12-54.pek2.redhat.com [10.72.12.54]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7829D40C6EC4; Thu, 1 Jun 2023 02:15:26 +0000 (UTC) Date: Thu, 1 Jun 2023 10:15:22 +0800 From: Baoquan He To: Anthony Yznaga Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, rppt@kernel.org, akpm@linux-foundation.org, ebiederm@xmission.com, keescook@chromium.org, graf@amazon.com, jason.zeng@intel.com, lei.l.li@intel.com, steven.sistare@oracle.com, fam.zheng@bytedance.com, mgalaxy@akamai.com, kexec@lists.infradead.org Subject: Re: [RFC v3 00/21] Preserved-over-Kexec RAM Message-ID: References: <1682554137-13938-1-git-send-email-anthony.yznaga@oracle.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1682554137-13938-1-git-send-email-anthony.yznaga@oracle.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230531_191537_792199_15082B8E X-CRM114-Status: GOOD ( 14.97 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 04/26/23 at 05:08pm, Anthony Yznaga wrote: > Sending out this RFC in part to guage community interest. > This patchset implements preserved-over-kexec memory storage or PKRAM as a > method for saving memory pages of the currently executing kernel so that > they may be restored after kexec into a new kernel. The patches are adapted > from an RFC patchset sent out in 2013 by Vladimir Davydov [1]. They > introduce the PKRAM kernel API. > > One use case for PKRAM is preserving guest memory and/or auxillary > supporting data (e.g. iommu data) across kexec to support reboot of the > host with minimal disruption to the guest. PKRAM provides a flexible way > for doing this without requiring that the amount of memory used by a fixed > size created a priori. Another use case is for databases to preserve their > block caches in shared memory across reboot. If so, I have confusions, who can help clarify: 1) Why kexec reboot was introduced, what do we expect kexec reboot to do? 2) If we need keep these data and those data, can we not reboot? They are definitely located there w/o any concern. 3) What if systems of AI, edge computing, HPC etc also want to carry kinds of data from userspace or kernel, system status, registers etc when kexec reboot is needed, while enligntened by this patch? Thanks Baoquan _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec