From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752684AbdDQKcc (ORCPT ); Mon, 17 Apr 2017 06:32:32 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:34941 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750896AbdDQKc3 (ORCPT ); Mon, 17 Apr 2017 06:32:29 -0400 Date: Mon, 17 Apr 2017 12:32:25 +0200 From: Ingo Molnar To: "Kirill A. Shutemov" Cc: Andi Kleen , "Kirill A. Shutemov" , Andy Lutomirski , Linus Torvalds , Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Dave Hansen , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/8] x86/boot/64: Add support of additional page table level during early boot Message-ID: <20170417103225.ycv73fdrfx33e5sd@gmail.com> References: <20170406140106.78087-1-kirill.shutemov@linux.intel.com> <20170406140106.78087-4-kirill.shutemov@linux.intel.com> <20170411070203.GA14621@gmail.com> <20170411105106.4zgbzuu4s4267zyv@node.shutemov.name> <20170411112845.GA15212@gmail.com> <20170411114616.otx2f6aw5lcvfc2o@black.fi.intel.com> <20170411140907.GD4021@tassilo.jf.intel.com> <20170412101804.cxo6h472ns76ukgo@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170412101804.cxo6h472ns76ukgo@node.shutemov.name> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Kirill A. Shutemov wrote: > On Tue, Apr 11, 2017 at 07:09:07AM -0700, Andi Kleen wrote: > > > I'll look closer (building proccess it's rather complicated), but my > > > understanding is that VDSO is stand-alone binary and doesn't really links > > > with the rest of the kernel, rather included as blob, no? > > > > > > Andy, may be you have an idea? > > > > There isn't any way I know of to directly link them together. The ELF > > format wasn't designed for that. You would need to merge blobs and then use > > manual jump vectors, like the 16bit startup code does. It would be likely > > complicated and ugly. > > Ingo, can we proceed without coverting this assembly to C? > > I'm committed to convert it to C later if we'll find reasonable solution > to the issue. So one way to do it would be to build it standalone as a .o, then add it not to the regular kernel objects link target (as you found out it's not possible to link 32-bit and 64-bit objects), but to link it in a manual fashion, as part of vmlinux.bin.all-y in arch/x86/boot/compressed/Makefile. But there would be other complications with this approach, such as we'd have to add a size field and there might be symbol linking problems ... Another, pretty hacky way would be to generate a .S from the .c, then post-process the .S and essentially generate today's 32-bit .S from it. Probably not worth the trouble. Thanks, Ingo From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH 3/8] x86/boot/64: Add support of additional page table level during early boot Date: Mon, 17 Apr 2017 12:32:25 +0200 Message-ID: <20170417103225.ycv73fdrfx33e5sd@gmail.com> References: <20170406140106.78087-1-kirill.shutemov@linux.intel.com> <20170406140106.78087-4-kirill.shutemov@linux.intel.com> <20170411070203.GA14621@gmail.com> <20170411105106.4zgbzuu4s4267zyv@node.shutemov.name> <20170411112845.GA15212@gmail.com> <20170411114616.otx2f6aw5lcvfc2o@black.fi.intel.com> <20170411140907.GD4021@tassilo.jf.intel.com> <20170412101804.cxo6h472ns76ukgo@node.shutemov.name> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170412101804.cxo6h472ns76ukgo@node.shutemov.name> Sender: owner-linux-mm@kvack.org To: "Kirill A. Shutemov" Cc: Andi Kleen , "Kirill A. Shutemov" , Andy Lutomirski , Linus Torvalds , Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Dave Hansen , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-Id: linux-arch.vger.kernel.org * Kirill A. Shutemov wrote: > On Tue, Apr 11, 2017 at 07:09:07AM -0700, Andi Kleen wrote: > > > I'll look closer (building proccess it's rather complicated), but my > > > understanding is that VDSO is stand-alone binary and doesn't really links > > > with the rest of the kernel, rather included as blob, no? > > > > > > Andy, may be you have an idea? > > > > There isn't any way I know of to directly link them together. The ELF > > format wasn't designed for that. You would need to merge blobs and then use > > manual jump vectors, like the 16bit startup code does. It would be likely > > complicated and ugly. > > Ingo, can we proceed without coverting this assembly to C? > > I'm committed to convert it to C later if we'll find reasonable solution > to the issue. So one way to do it would be to build it standalone as a .o, then add it not to the regular kernel objects link target (as you found out it's not possible to link 32-bit and 64-bit objects), but to link it in a manual fashion, as part of vmlinux.bin.all-y in arch/x86/boot/compressed/Makefile. But there would be other complications with this approach, such as we'd have to add a size field and there might be symbol linking problems ... Another, pretty hacky way would be to generate a .S from the .c, then post-process the .S and essentially generate today's 32-bit .S from it. Probably not worth the trouble. Thanks, Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . 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