From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8F2481A08B8 for ; Sun, 3 Aug 2025 04:05:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754193956; cv=none; b=up7ucqTjRVIe3oeIpdThEAGWzHVBG5WfWbVOsGvi2qBtwY1U8UoFkK4/FsQk5oNMxN++Ap9QNWTAmpYi1tQXTrEC4p1c76lLdhVf+EnwrtIzM53jD7ofnlkzgzQDrOuvNvzXyD5wTcsyQXgLO/Of3vryYfRAqAc4uMYWQ7gpMfU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754193956; c=relaxed/simple; bh=h/k6ojZO8XiSn6OLsgC0yQY/fafYJVlLS5/4h77f/g0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KDuAGEpXAJfYuuSg6sXW4jf6sTnORJr1+3WjwNta3kpTgCxBplx9Mw6uULPRd0V/XG+FXYH1264Mf+AMX2J8wEz7bpEHvo8XWs4cY5w1SidxzWCEqP+Z5IVuNcJDRCGbNztgqpSxgM5//Wbq+eULoZNkCMu4+XcdjNveShPGIS8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=dj5jaYhm; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dj5jaYhm" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1754193950; 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=EoOkZOeOKNBWaDehCjjVCVpOpwcj59N5p8x5bREgwH8=; b=dj5jaYhmyK6BAYvOzHFz0pZPA7klbS/Rn2Be0S0hfsz7MU63ZJfC7dZFOGRKC75BJByDuX CLLj9qyzWEsTfEHShPUKeSLalJkFcqWUcI3UG6KFNmawXAh8RqPQPvMyXzf2XaEwGOtZe+ Op4BUs5DzSqz2i01+0UYlWRerSMGtoc= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-630-95tvEVS2PE-gfrSu9SPQRw-1; Sun, 03 Aug 2025 00:05:43 -0400 X-MC-Unique: 95tvEVS2PE-gfrSu9SPQRw-1 X-Mimecast-MFC-AGG-ID: 95tvEVS2PE-gfrSu9SPQRw_1754193934 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 55423195609D; Sun, 3 Aug 2025 04:05:33 +0000 (UTC) Received: from localhost (unknown [10.72.112.43]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 82EB63000199; Sun, 3 Aug 2025 04:05:30 +0000 (UTC) Date: Sun, 3 Aug 2025 12:05:26 +0800 From: Baoquan He To: Brian Mak Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Andrew Morton , Rob Herring , Saravana Kannan , "x86@kernel.org" , "kexec@lists.infradead.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH RESEND] x86/kexec: Carry forward the boot DTB on kexec Message-ID: References: <20250729182142.4875-1-makb@juniper.net> <5A9FE2FF-800A-4458-9929-124EB89FE1D9@juniper.net> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5A9FE2FF-800A-4458-9929-124EB89FE1D9@juniper.net> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On 08/01/25 at 07:24pm, Brian Mak wrote: > On Jul 31, 2025, at 8:02 PM, Baoquan He wrote: > > > On 07/29/25 at 11:21am, Brian Mak wrote: > >> The kexec_file_load syscall on x86 currently does not support passing > >> a device tree blob to the new kernel. > >> > >> To add support for this, we copy the behavior of ARM64 and PowerPC and > >> copy the current boot's device tree blob for use in the new kernel. We > >> do this on x86 by passing the device tree blob as a setup_data entry in > >> accordance with the x86 boot protocol. > > > > I see how, but no why. Why do we need to add DTB for x86? > > Hi Baoquan, > > Thanks for your comment. Some embedded x86 systems, such as ours at > Juniper, use device trees. Currently, the x86 kexec_file_load syscall > has no support for passing the device tree to the new kernel, which is a > problem for us since we use kexec for some software upgrade related > features. Not passing a device tree to the new kernel would cause a boot > failure here. Thanks for the info. Please add these into patch log to let reviewers know them. We don't add code w/o objective.