From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Horman Subject: Re: x86-64/kexec: crashkernel= without @xM suffix Date: Sun, 2 May 2010 12:21:41 +1000 Message-ID: <20100502022140.GE5304@verge.net.au> References: <4BDA97DE0200007800000C43@vpn.id2.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4BDA97DE0200007800000C43@vpn.id2.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jan Beulich Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Fri, Apr 30, 2010 at 07:42:06AM +0100, Jan Beulich wrote: > Was this ever tested by anyone? Has it ever worked with any Linux > as secondary kernel? We're getting reports (and analysis confirms > this) that the fact that Xen places the hole at the highest suitable > address below 4G prevents kexec from working. > > A possible fix is non-obvious, since there doesn't appear to be a > hard boundary below which the hole must reside (especially for a > 32-bit secondary kernel; for a 64-bit one it seems like any place > below 2G would be acceptable). > > Simply using Linux' strategy and allocating at the lowest possible > address doesn't seem too nice a solution either, as we try to > conserve on the use of low memory as much as possible almost > everywhere else. Hi Jan, I don't recall specifically testing this combination. I think that your suggestion of simply locating the hole as low as possible is a good one though I fear there is a gotcha in there somewhere.