From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755903Ab2KUTpu (ORCPT ); Wed, 21 Nov 2012 14:45:50 -0500 Received: from mail-bk0-f46.google.com ([209.85.214.46]:58325 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755818Ab2KUTpt (ORCPT ); Wed, 21 Nov 2012 14:45:49 -0500 MIME-Version: 1.0 In-Reply-To: <50AD0E22.3020807@zytor.com> References: <1353482170-10160-1-git-send-email-yinghai@kernel.org> <1353482170-10160-2-git-send-email-yinghai@kernel.org> <50AD0E22.3020807@zytor.com> Date: Wed, 21 Nov 2012 11:45:47 -0800 X-Google-Sender-Auth: Vta8fJeRlhlVn9uzFSgyEElWkl4 Message-ID: Subject: Re: [PATCH v3 01/12] x86, boot: move verify_cpu.S after 0x200 From: Yinghai Lu To: "H. Peter Anvin" Cc: Thomas Gleixner , Ingo Molnar , "Eric W. Biederman" , linux-kernel@vger.kernel.org, Matt Fleming Content-Type: multipart/mixed; boundary=000e0ce0452cd5bfb704cf069811 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --000e0ce0452cd5bfb704cf069811 Content-Type: text/plain; charset=ISO-8859-1 On Wed, Nov 21, 2012 at 9:23 AM, H. Peter Anvin wrote: > On 11/20/2012 11:15 PM, Yinghai Lu wrote: >> >> We are short of space before 0x200 that is entry for startup_64. >> >> And we can not change startup_64 to other value --- ABI ? > > > Here you are saying "I don't understand how this works." It is YOUR > responsibility to find out and write a definite statement rather than > leaving that to the reader, or expect the maintainer to edit this. actually, i can not find that out. in the code of arch/x86/boot/compressed/head_64.S /* * Be careful here startup_64 needs to be at a predictable * address so I can export it in an ELF header. Bootloaders * should look at the ELF header to find this address, as * it may change in the future. */ .code64 .org 0x200 ENTRY(startup_64) /* * We come here either from startup_32 or directly from a * 64bit bootloader. If we come here from a bootloader we depend on * an identity mapped page table being provied that maps our * entire text+data+bss and hopefully all of memory. */ #ifdef CONFIG_EFI_STUB /* * The entry point for the PE/COFF executable is 0x210, so only * legacy boot loaders will execute this jmp. */ jmp preferred_addr .org 0x210 mov %rcx, %rdi and it says that 0x200 will be changed later.. so you said it has to stay with 0x200, do you mean 0x210 from PE/COFF force that? wonder if you are considering attatched patch to move startup_64 down... we could kill one jmp. 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