From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f194.google.com ([209.85.216.194]:37363 "EHLO mail-qt0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751165AbeDENmK (ORCPT ); Thu, 5 Apr 2018 09:42:10 -0400 Received: by mail-qt0-f194.google.com with SMTP id w12so26921230qti.4 for ; Thu, 05 Apr 2018 06:42:10 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <4bf257f2-dad7-62d2-ad5b-8972c0311119@suse.com> References: <20180404142702.GA20460@kroah.com> <20180404144644.GA22656@kroah.com> <20180404154201.GA31981@kroah.com> <9cd0be43-6380-f5a0-0427-7f75fca966a9@suse.com> <20180405063314.GC5431@kroah.com> <20180405071448.GA9183@kroah.com> <950f2f68-04ef-bf4d-fa61-afa9bdc918e4@suse.com> <4bf257f2-dad7-62d2-ad5b-8972c0311119@suse.com> From: George Dunlap Date: Thu, 5 Apr 2018 14:42:09 +0100 Message-ID: Subject: Re: [Xen-devel] Patches for stable To: Juergen Gross Cc: Boris Ostrovsky , Greg KH , stable , xen-devel Content-Type: text/plain; charset="UTF-8" Sender: stable-owner@vger.kernel.org List-ID: On Thu, Apr 5, 2018 at 2:06 PM, Juergen Gross wrote: > On 05/04/18 15:00, Boris Ostrovsky wrote: >> On 04/05/2018 08:19 AM, Juergen Gross wrote: >>> On 05/04/18 12:06, George Dunlap wrote: >>> >>>> Aren't there flags in the binary somewhere that could tell the >>>> toolstack / Xen whether the kernel in question needs the RSDP table in >>>> lowmem, or whether it can be put higher? >>> Not really. Analyzing the binary whether it accesses the rsdp_addr in >>> the start_info isn't the way to go, IMO. >>> >>> I've sent a patch to xen-devel adding a quirk flag to the domain's >>> config to enable the admin special casing such an "old" kernel. >> >> Can we backport latest struct hvm_start_info changes (which bumped >> interface version) to 4.11 and pass RSDP only for versions >=1? > > And this would help how? > > RSDP address is passed today, the kernel just doesn't read it. And > how should Xen know which interface version the kernel is supporting? > And Xen needs to know that in advance in order to place the RSDP in > low memory in case the kernel isn't reading the RSDP address from > start_info. But the kernel image has ELF notes, right? You can put one that indicates that this binary *does* know how to read the RSDP from the start_info, and if you don't find that, put it in lowmem. -George