freebsd-skq/sys/boot/i386/loader/conf.c
Roger Pau Monné ca49b3342d loader: implement multiboot support for Xen Dom0
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>
2015-01-15 16:27:20 +00:00

164 lines
4.2 KiB
C

/*-
* Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <stand.h>
#include <bootstrap.h>
#include "libi386/libi386.h"
#if defined(LOADER_ZFS_SUPPORT)
#include "../zfs/libzfs.h"
#endif
/*
* We could use linker sets for some or all of these, but
* then we would have to control what ended up linked into
* the bootstrap. So it's easier to conditionalise things
* here.
*
* XXX rename these arrays to be consistent and less namespace-hostile
*
* XXX as libi386 and biosboot merge, some of these can become linker sets.
*/
#if defined(LOADER_NFS_SUPPORT) && defined(LOADER_TFTP_SUPPORT)
#error "Cannot have both tftp and nfs support yet."
#endif
#if defined(LOADER_FIREWIRE_SUPPORT)
extern struct devsw fwohci;
#endif
/* Exported for libstand */
struct devsw *devsw[] = {
&bioscd,
&biosdisk,
#if defined(LOADER_NFS_SUPPORT) || defined(LOADER_TFTP_SUPPORT)
&pxedisk,
#endif
#if defined(LOADER_FIREWIRE_SUPPORT)
&fwohci,
#endif
#if defined(LOADER_ZFS_SUPPORT)
&zfs_dev,
#endif
NULL
};
struct fs_ops *file_system[] = {
#if defined(LOADER_ZFS_SUPPORT)
&zfs_fsops,
#endif
&ufs_fsops,
&ext2fs_fsops,
&dosfs_fsops,
&cd9660_fsops,
#if defined(LOADER_NANDFS_SUPPORT)
&nandfs_fsops,
#endif
#ifdef LOADER_NFS_SUPPORT
&nfs_fsops,
#endif
#ifdef LOADER_TFTP_SUPPORT
&tftp_fsops,
#endif
#ifdef LOADER_GZIP_SUPPORT
&gzipfs_fsops,
#endif
#ifdef LOADER_BZIP2_SUPPORT
&bzipfs_fsops,
#endif
#ifdef LOADER_SPLIT_SUPPORT
&splitfs_fsops,
#endif
NULL
};
/* Exported for i386 only */
/*
* Sort formats so that those that can detect based on arguments
* rather than reading the file go first.
*/
extern struct file_format i386_elf;
extern struct file_format i386_elf_obj;
extern struct file_format amd64_elf;
extern struct file_format amd64_elf_obj;
extern struct file_format multiboot;
extern struct file_format multiboot_obj;
struct file_format *file_formats[] = {
&multiboot,
&multiboot_obj,
#ifdef LOADER_PREFER_AMD64
&amd64_elf,
&amd64_elf_obj,
#endif
&i386_elf,
&i386_elf_obj,
#ifndef LOADER_PREFER_AMD64
&amd64_elf,
&amd64_elf_obj,
#endif
NULL
};
/*
* Consoles
*
* We don't prototype these in libi386.h because they require
* data structures from bootstrap.h as well.
*/
extern struct console vidconsole;
extern struct console comconsole;
#if defined(LOADER_FIREWIRE_SUPPORT)
extern struct console dconsole;
#endif
extern struct console nullconsole;
extern struct console spinconsole;
struct console *consoles[] = {
&vidconsole,
&comconsole,
#if defined(LOADER_FIREWIRE_SUPPORT)
&dconsole,
#endif
&nullconsole,
&spinconsole,
NULL
};
extern struct pnphandler isapnphandler;
extern struct pnphandler biospnphandler;
extern struct pnphandler biospcihandler;
struct pnphandler *pnphandlers[] = {
&biospnphandler, /* should go first, as it may set isapnp_readport */
&isapnphandler,
&biospcihandler,
NULL
};