From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] xen: find a better location for the real-mode trampoline Date: Tue, 18 Dec 2012 14:39:04 +0100 Message-ID: <50D071F8.8040509@redhat.com> References: <1354210461-9739-1-git-send-email-pbonzini@redhat.com> <50B87D6E02000078000ACBF2@nat28.tlf.novell.com> <50D078B702000078000B101F@nat28.tlf.novell.com> <50D06E04.7030904@redhat.com> <50D07D4802000078000B1071@nat28.tlf.novell.com> <50D06F90.6070803@redhat.com> <50D07F8802000078000B1091@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <50D07F8802000078000B1091@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@lists.xen.org List-Id: xen-devel@lists.xenproject.org Il 18/12/2012 14:36, Jan Beulich ha scritto: >>>> >>> No, just busy. I agree that checking all three is best. However, there >>>> >>> is at least one known case where 0x40e doesn't work, so 0x413 and >>>> >>> multiboot should be enough. >>> >> >>> >> Can you provide more detail about this specific case? In >>> >> particular, what value 0x40e in fact has there? >> > >> > Sure. 0x40e did point to the beginning of the EBDA (around 635k), but >> > an option ROM was reserving memory below there by lowering 0x413. >> > That's the "on some machines" in the commit message. > That wouldn't preclude the suggested sanity-checked-minimum > solution. Yes, on the other hand [0x413] should always be less than or equal to [0x40e] << 6. Otherwise for example DOS would not work on that system. Paolo