From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCHv11 3/9] kexec: add infrastructure for handling kexec images Date: Fri, 15 Nov 2013 18:31:29 +0000 Message-ID: <52866881.6070003@citrix.com> References: <1383749386-11891-4-git-send-email-david.vrabel@citrix.com> <1383915029-25468-1-git-send-email-david.vrabel@citrix.com> <52863F2F0200007800103970@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VhOB4-0006vk-1v for xen-devel@lists.xenproject.org; Fri, 15 Nov 2013 18:31:34 +0000 In-Reply-To: <52863F2F0200007800103970@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: xen-devel , Daniel Kiper , David Vrabel List-Id: xen-devel@lists.xenproject.org On 15/11/13 14:35, Jan Beulich wrote: >>>> On 08.11.13 at 13:50, David Vrabel wrote: >> Add the code needed to handle and load kexec images into Xen memory or >> into the crash region. This is needed for the new KEXEC_CMD_load and >> KEXEC_CMD_unload hypercall sub-ops. > > I know it's late in the game, but just now I started getting the > impression that this introduced a new limitation that needs to > be taken into consideration elsewhere: With the old > implementation it was the kernel's responsibility to write to > the reserved space or, where Xen needed to touch the space, > it did so via fixmap entries. Hence there was no need for the > area to have corresponding struct page_info. > > The new code, however, appears to make assumptions that > the memory used here is part of the range covered by the > frame table, and hence setup.c's determination of the base > address would need to be adjusted accordingly. (I realize > that this only matters on systems having more RAM than the > hypervisor can make use of.) The relocation code wrote the image into the crash region, not the kernel, but I take your point. Is this a real problem or just a theoretical one for now? I don't think it's unreasonable to require the crash region to be within the frame table. David