From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755515AbYEXJub (ORCPT ); Sat, 24 May 2008 05:50:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754051AbYEXJuW (ORCPT ); Sat, 24 May 2008 05:50:22 -0400 Received: from gw.goop.org ([64.81.55.164]:33138 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753372AbYEXJuW (ORCPT ); Sat, 24 May 2008 05:50:22 -0400 Message-ID: <4837E4BF.6050604@goop.org> Date: Sat, 24 May 2008 10:49:51 +0100 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Yinghai Lu CC: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andrew Morton , "linux-kernel@vger.kernel.org" Subject: [PATCH] xen: boot via i386_start_kernel to get early reservations References: <200805110030.15510.yhlu.kernel@gmail.com> <200805180118.57863.yhlu.kernel@gmail.com> <200805211840.18619.yhlu.kernel@gmail.com> <200805221520.19259.yhlu.kernel@gmail.com> <4837D7DD.7000204@goop.org> In-Reply-To: <4837D7DD.7000204@goop.org> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Boot Xen via i386_start_kernel so that all the early reservations are made properly; without these, it will start using the kernel and pagetables as early heap memory, which is a bit suboptimal. One tricky part is that reserve_early() will just panic if any of the early reservations overlap any others. When a Xen domain is built, it constructs the initial address space as: kernel text+data+bss initrd initial pagetable Therefore, when reserving the pagetable (from &_end to init_pg_tables_end), it covers the whole initrd area. If it then tries to reserve the initrd, it will panic because of the overlap. The simple fix here is to reserve INIT_PG_TABLE first, and then only reserve the ramdisk if it doesn't overlap with the previous reservations. A better/more complex fix might be to make reserve_early() deal with overlapping reservations. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/kernel/head32.c | 6 ++++-- arch/x86/xen/enlighten.c | 2 +- include/asm-x86/setup.h | 1 + 3 files changed, 6 insertions(+), 3 deletions(-) =================================================================== --- a/arch/x86/kernel/head32.c +++ b/arch/x86/kernel/head32.c @@ -66,6 +66,7 @@ void __init i386_start_kernel(void) void __init i386_start_kernel(void) { reserve_early(__pa_symbol(&_text), __pa_symbol(&_end), "TEXT DATA BSS"); + reserve_early(__pa_symbol(&_end), init_pg_tables_end, "INIT_PG_TABLE"); #ifdef CONFIG_BLK_DEV_INITRD /* Reserve INITRD */ @@ -73,10 +74,11 @@ void __init i386_start_kernel(void) u64 ramdisk_image = boot_params.hdr.ramdisk_image; u64 ramdisk_size = boot_params.hdr.ramdisk_size; u64 ramdisk_end = ramdisk_image + ramdisk_size; - reserve_early(ramdisk_image, ramdisk_end, "RAMDISK"); + if (ramdisk_end <= __pa_symbol(&_text) || + ramdisk_image > init_pg_tables_end) + reserve_early(ramdisk_image, ramdisk_end, "RAMDISK"); } #endif - reserve_early(__pa_symbol(&_end), init_pg_tables_end, "INIT_PG_TABLE"); reserve_ebda_region(); =================================================================== --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1264,5 +1264,5 @@ asmlinkage void __init xen_start_kernel( } /* Start the world */ - start_kernel(); + i386_start_kernel(); } =================================================================== --- a/include/asm-x86/setup.h +++ b/include/asm-x86/setup.h @@ -58,6 +58,7 @@ int __init copy_e820_map(struct e820entr int __init copy_e820_map(struct e820entry *biosmap, int nr_map); void __init add_memory_region(unsigned long long start, unsigned long long size, int type); +void __init i386_start_kernel(void); extern unsigned long init_pg_tables_end;