From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: [PATCH 18/18] x86: add multiboot2 protocol support for EFI platforms Date: Fri, 27 Mar 2015 15:06:43 +0000 Message-ID: <55158013020000780006EB39__18281.5596847378$1427468955$gmane$org@mail.emea.novell.com> References: <1422640462-28103-1-git-send-email-daniel.kiper@oracle.com> <1422640462-28103-19-git-send-email-daniel.kiper@oracle.com> <550810B1020000780006AA3A@mail.emea.novell.com> <20150327130652.GM8294@olila.local.net-space.pl> <55156AF0020000780006E92B@mail.emea.novell.com> <20150327142626.GP8294@olila.local.net-space.pl> <5515787C020000780006EA96@mail.emea.novell.com> <20150327145746.GA440@olila.local.net-space.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YbVqQ-0004Hk-9q for xen-devel@lists.xenproject.org; Fri, 27 Mar 2015 15:06:46 +0000 In-Reply-To: <20150327145746.GA440@olila.local.net-space.pl> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Daniel Kiper Cc: Juergen Gross , grub-devel@gnu.org, keir@xen.org, ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com, andrew.cooper3@citrix.com, roy.franz@linaro.org, ning.sun@intel.com, david.vrabel@citrix.com, phcoder@gmail.com, xen-devel@lists.xenproject.org, qiaowei.ren@intel.com, richard.l.maliszewski@intel.com, gang.wei@intel.com, fu.wei@linaro.org List-Id: xen-devel@lists.xenproject.org >>> On 27.03.15 at 15:57, wrote: > On Fri, Mar 27, 2015 at 02:34:19PM +0000, Jan Beulich wrote: >> >>> On 27.03.15 at 15:26, wrote: >> > On Fri, Mar 27, 2015 at 01:36:32PM +0000, Jan Beulich wrote: >> >> >>> On 27.03.15 at 14:06, wrote: >> >> > On Tue, Mar 17, 2015 at 10:32:01AM +0000, Jan Beulich wrote: >> >> >> >>> On 30.01.15 at 18:54, wrote: >> >> >> > + /* Skip Multiboot2 information fixed part */ >> >> >> > + lea MB2_fixed_sizeof(%ebx),%ecx >> >> >> >> >> >> Let's please not add more assumptions than necessary about stuff >> >> >> being below 4G. >> >> > >> >> > I am not sure what do you mean by that. >> >> >> >> See the 32-bit register used for addressing here (and in many more >> >> places)? >> > >> > This is what I expected but I was confused because you were referring only >> > here to this problem. Anyway, is it possible to do this in different way? >> > Should we care if image is always loaded at 0x100000 right now? Even with >> > Xen early boot code being relocatable loader could not load image higher >> > than 0xffffffff - 14 MiB. >> >> I don't understand what you're alluding to. Just use 64-bit registers >> for memory accesses and LEAs, and be done. This will result in smaller >> code as a benefit. > > Well... How can I do that here if processor is in 32-bit mode? Maybe, > we could that things after switching to 64-bit mode. However, I think > this requires separate patch to do these changes. No, if the processor is in 32-bit mode, then using 32-bit registers is fine of course. But I'm pretty certain I spotted at least some cases where it looked like you used 32-bit registers in 64-bit mode. Jan