ca49b3342d
Implement a subset of the multiboot specification in order to boot Xen and a FreeBSD Dom0 from the FreeBSD bootloader. This multiboot implementation is tailored to boot Xen and FreeBSD Dom0, and it will most surely fail to boot any other multiboot compilant kernel. In order to detect and boot the Xen microkernel, two new file formats are added to the bootloader, multiboot and multiboot_obj. Multiboot support must be tested before regular ELF support, since Xen is a multiboot kernel that also uses ELF. After a multiboot kernel is detected, all the other loaded kernels/modules are parsed by the multiboot_obj format. The layout of the loaded objects in memory is the following; first the Xen kernel is loaded as a 32bit ELF into memory (Xen will switch to long mode by itself), after that the FreeBSD kernel is loaded as a RAW file (Xen will parse and load it using it's internal ELF loader), and finally the metadata and the modules are loaded using the native FreeBSD way. After everything is loaded we jump into Xen's entry point using a small trampoline. The order of the multiboot modules passed to Xen is the following, the first module is the RAW FreeBSD kernel, and the second module is the metadata and the FreeBSD modules. Since Xen will relocate the memory position of the second multiboot module (the one that contains the metadata and native FreeBSD modules), we need to stash the original modulep address inside of the metadata itself in order to recalculate its position once booted. This also means the metadata must come before the loaded modules, so after loading the FreeBSD kernel a portion of memory is reserved in order to place the metadata before booting. In order to tell the loader to boot Xen and then the FreeBSD kernel the following has to be added to the /boot/loader.conf file: xen_cmdline="dom0_mem=1024M dom0_max_vcpus=2 dom0pvh=1 console=com1,vga" xen_kernel="/boot/xen" The first argument contains the command line that will be passed to the Xen kernel, while the second argument is the path to the Xen kernel itself. This can also be done manually from the loader command line, by for example typing the following set of commands: OK unload OK load /boot/xen dom0_mem=1024M dom0_max_vcpus=2 dom0pvh=1 console=com1,vga OK load kernel OK load zfs OK load if_tap OK load ... OK boot Sponsored by: Citrix Systems R&D Reviewed by: jhb Differential Revision: https://reviews.freebsd.org/D517 For the Forth bits: Submitted by: Julien Grall <julien.grall AT citrix.com>
52 lines
2.1 KiB
ArmAsm
52 lines
2.1 KiB
ArmAsm
/*-
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* Copyright (c) 2014 Roger Pau Monné <royger@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#define ASM_FILE
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#include "multiboot.h"
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/*
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* The multiboot specification requires the executable to be launched
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* with %cs set to a flat read/execute segment with offset 0 and limit
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* 0xFFFFFFFF, and the rest of the segment registers (%ds, %es, %fs,
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* %gs, %ss) to flat read/write segments with the same offset and limit.
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* This is already done by the BTX code before calling multiboot_tramp,
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* so there is no need to do anything here.
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*/
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.globl multiboot_tramp
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multiboot_tramp:
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/* Be sure that interrupts are disabled. */
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cli
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movl $MULTIBOOT_BOOTLOADER_MAGIC, %eax
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/* Get the entry point and address of the multiboot_info parameter. */
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movl 8(%esp), %ebx
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movl 4(%esp), %ecx
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call *%ecx
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