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barebox/commands/linux16.c
Sascha Hauer ee4cab9e58 booting: more flexible Linux bootargs generation 
We currently use the environment variable 'bootargs' to get the
Linux bootargs. This patch allows for a more flexible bootargs
generation using global variables. With it the Linux bootargs
are concatenated from multiple variables. This allows to replace
parts of the bootargs string without having to reconstruct it
completely.
With this bootargs can be constructed like:

global linux.bootargs.base="console=ttyS0,115200"
global linux.bootargs.ip="ip=dhcp"
global linux.mtdparts="physmap-flash.0:512K(nor0.barebox),-(root)"

This will then automatically be combined into a kernel bootargs
string during boot.

If the 'linux.bootargs.' variables are all empty the old standard
'bootargs' way will be used.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
2012-05-14 09:16:31 +02:00

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/*
* Copyright (C) 2009 Juergen Beisert, Pengutronix
*
* In parts from the GRUB2 project:
*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2007,2008 Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*
*/
#include <common.h>
#include <command.h>
#include <environment.h>
#include <fs.h>
#include <errno.h>
#include <getopt.h>
#include <malloc.h>
#include <asm/syslib.h>
/** FIXME */
#define LINUX_MAGIC_SIGNATURE 0x53726448 /* "HdrS" */
/** FIXME */
#define LINUX_FLAG_BIG_KERNEL 0x1
/** FIXME */
#define LINUX_BOOT_LOADER_TYPE 0x72
/** FIXME */
#define LINUX_DEFAULT_SETUP_SECTS 4
/** FIXME */
#define LINUX_MAX_SETUP_SECTS 64
/** FIXME */
#define LINUX_OLD_REAL_MODE_SEGMT 0x9000
/** FIXME */
#define LINUX_OLD_REAL_MODE_ADDR (LINUX_OLD_REAL_MODE_SEGMT << 4)
/** FIXME */
#define LINUX_HEAP_END_OFFSET (LINUX_OLD_REAL_MODE_SEGMT - 0x200)
/** FIXME */
#define LINUX_FLAG_CAN_USE_HEAP 0x80
/** Define kernel command lines's start offset in the setup segment */
#define LINUX_CL_OFFSET 0x9000
/** Define kernel command lines's end offset */
#define LINUX_CL_END_OFFSET 0x90FF
/** FIXME */
#define LINUX_CL_MAGIC 0xA33F
/** FIXME */
#define LINUX_SETUP_MOVE_SIZE 0x9100
/** Sector size */
#define DISK_SECTOR_BITS 9
#define DISK_SECTOR_SIZE 0x200
/** Where to load a bzImage */
#define LINUX_BZIMAGE_ADDR 0x100000
struct linux_kernel_header {
/* first sector of the image */
uint8_t code1[0x0020];
uint16_t cl_magic; /**< Magic number 0xA33F */
uint16_t cl_offset; /**< The offset of command line */
uint8_t code2[0x01F1 - 0x0020 - 2 - 2];
uint8_t setup_sects; /**< The size of the setup in sectors */
uint16_t root_flags; /**< If the root is mounted readonly */
uint16_t syssize; /**< obsolete */
uint16_t swap_dev; /**< obsolete */
uint16_t ram_size; /**< obsolete */
uint16_t vid_mode; /**< Video mode control */
uint16_t root_dev; /**< Default root device number */
uint16_t boot_flag; /**< 0xAA55 magic number */
/* second sector of the image */
uint16_t jump; /**< Jump instruction (this is code!) */
uint32_t header; /**< Magic signature "HdrS" */
uint16_t version; /**< Boot protocol version supported */
uint32_t realmode_swtch; /**< Boot loader hook */
uint16_t start_sys; /**< The load-low segment (obsolete) */
uint16_t kernel_version; /**< Points to kernel version string */
uint8_t type_of_loader; /**< Boot loader identifier */
#define LINUX_LOADER_ID_LILO 0x0
#define LINUX_LOADER_ID_LOADLIN 0x1
#define LINUX_LOADER_ID_BOOTSECT 0x2
#define LINUX_LOADER_ID_SYSLINUX 0x3
#define LINUX_LOADER_ID_ETHERBOOT 0x4
#define LINUX_LOADER_ID_ELILO 0x5
#define LINUX_LOADER_ID_GRUB 0x7
#define LINUX_LOADER_ID_UBOOT 0x8
#define LINUX_LOADER_ID_XEN 0x9
#define LINUX_LOADER_ID_GUJIN 0xa
#define LINUX_LOADER_ID_QEMU 0xb
uint8_t loadflags; /**< Boot protocol option flags */
uint16_t setup_move_size; /**< Move to high memory size */
uint32_t code32_start; /**< Boot loader hook */
uint32_t ramdisk_image; /**< initrd load address */
uint32_t ramdisk_size; /**< initrd size */
uint32_t bootsect_kludge; /**< obsolete */
uint16_t heap_end_ptr; /**< Free memory after setup end */
uint8_t ext_loader_ver; /**< boot loader's extension of the version number */
uint8_t ext_loader_type; /**< boot loader's extension of its type */
char *cmd_line_ptr; /**< Points to the kernel command line */
uint32_t initrd_addr_max; /**< Highest address for initrd */
#if 0
/* for the records only. These members are defined in
* more recent Linux kernels
*/
uint32_t kernel_alignment; /**< Alignment unit required by the kernel */
uint8_t relocatable_kernel; /** */
uint8_t min_alignment; /** */
uint32_t cmdline_size; /** */
uint32_t hardware_subarch; /** */
uint64_t hardware_subarch_data; /** */
uint32_t payload_offset; /** */
uint32_t payload_length; /** */
uint64_t setup_data; /** */
uint64_t pref_address; /** */
uint32_t init_size; /** */
#endif
} __attribute__ ((packed));
/* This is -1. Keep this value in sync with the kernel */
#define NORMAL_VGA 0xffff /* 80x25 mode */
#define ASK_VGA 0xfffd /* ask for it at bootup */
/**
* Load an x86 Linux kernel bzImage and start it
* @param argc parameter count
* @param argv list of parameter
*
* Loads an x86 bzImage, checks for its integrity, stores the two parts
* (setup = 'real mode code' and kernel = 'protected mode code') to their
* default locations, switches back to real mode and runs the setup code.
*/
static int do_linux16(int argc, char *argv[])
{
struct linux_kernel_header *lh = NULL;
int rc, opt;
unsigned setup_sects;
unsigned real_mode_size;
int vid_mode = NORMAL_VGA;
size_t image_size;
const char *cmdline = linux_bootargs_get();
const char *kernel_file;
while((opt = getopt(argc, argv, "v:")) > 0) {
switch(opt) {
case 'v':
vid_mode = simple_strtoul(optarg, NULL, 0);
if (vid_mode == 0) {
if (!strcmp(optarg, "ask"))
vid_mode = ASK_VGA;
else {
printf("Unknown video mode: %s\n", optarg);
return 1;
}
}
break;
}
}
if (optind == argc) {
printf("No kernel filename given\n");
return 1;
}
kernel_file = argv[optind];
lh = read_file(kernel_file, &image_size);
if (lh == NULL) {
printf("Cannot read file '%s'\n", argv[1]);
return 1;
}
if (lh->boot_flag != 0xaa55) {
printf("File '%s' has invalid magic number\n", argv[1]);
rc = 1;
goto on_error;
}
if (lh->setup_sects > LINUX_MAX_SETUP_SECTS) {
printf("File '%s' contains too many setup sectors\n", argv[1]);
rc = 1;
goto on_error;
}
setup_sects = lh->setup_sects;
printf("Found a %d.%d image header\n", lh->version >> 8, lh->version & 0xFF);
if (lh->header == LINUX_MAGIC_SIGNATURE && lh->version >= 0x0200) {
/* kernel is recent enough */
;
if (!(lh->loadflags & LINUX_FLAG_BIG_KERNEL)) {
printf("Cannot load a classic zImage. Use a bzImage instead\n");
goto on_error;
}
lh->type_of_loader = LINUX_BOOT_LOADER_TYPE; /* TODO */
if (lh->version >= 0x0201) {
lh->heap_end_ptr = LINUX_HEAP_END_OFFSET;
lh->loadflags |= LINUX_FLAG_CAN_USE_HEAP;
}
if (lh->version >= 0x0202)
lh->cmd_line_ptr = (void*)(LINUX_OLD_REAL_MODE_ADDR + LINUX_CL_OFFSET); /* FIXME */
else {
lh->cl_magic = LINUX_CL_MAGIC;
lh->cl_offset = LINUX_CL_OFFSET;
lh->setup_move_size = LINUX_SETUP_MOVE_SIZE;
}
} else {
printf("Kernel too old to handle\n");
rc = 1;
goto on_error;
}
if (strlen(cmdline) >= (LINUX_CL_END_OFFSET - LINUX_CL_OFFSET)) {
printf("Kernel command line exceeds the available space\n");
rc = 1;
goto on_error;
}
/*
* The kernel does not check for the "vga=<val>" kernel command line
* parameter anymore. It expects this kind of information in the
* boot parameters instead.
*/
if (vid_mode != NORMAL_VGA)
lh->vid_mode = vid_mode;
/* If SETUP_SECTS is not set, set it to the default. */
if (setup_sects == 0) {
printf("Fixing setup sector count\n");
setup_sects = LINUX_DEFAULT_SETUP_SECTS;
}
if (setup_sects >= 15) {
void *src = lh;
if (lh->kernel_version != 0)
printf("Kernel version: '%s'\n",
(char *)src + lh->kernel_version + DISK_SECTOR_SIZE);
}
/*
* Size of the real mode part to handle in a separate way
*/
real_mode_size = (setup_sects << DISK_SECTOR_BITS) + DISK_SECTOR_SIZE;
/*
* real mode space hole extended memory
* |---------------------------------------------->|----------->|------------------------------>
* 0 0xa0000 0x100000
* <-1-|----------2-----------><-3- |
* 0x7e00 0x90000
* <-4--|-5--> |---------6------------->
*
* 1) real mode stack
* 2) barebox code
* 3) flat mode stack
* 4) realmode stack when starting a Linux kernel
* 5) Kernel's real mode setup code
* 6) compressed kernel image
*/
/*
* Parts of the image we know:
* - real mode part
* - kernel payload
*/
/*
* NOTE: This part is dangerous, as it copies some image content to
* various locations in the main memory. This could overwrite important
* data of the running barebox (hopefully not)
*/
/* copy the real mode part of the image to the 9th segment */
memcpy((void*)LINUX_OLD_REAL_MODE_ADDR, lh, LINUX_SETUP_MOVE_SIZE);
/* TODO add 'BOOT_IMAGE=<file>' and 'auto' if no user intervention was done (in front of all other params) */
/* copy also the command line into this area */
memcpy((void*)(LINUX_OLD_REAL_MODE_ADDR + LINUX_CL_OFFSET), cmdline, strlen(cmdline) + 1);
printf("Using kernel command line: '%s'\n", cmdline);
/* copy the compressed image part to its final address the setup code expects it
* Note: The protected mode part starts at offset (setup_sects + 1) * 512
*/
memcpy((void*)LINUX_BZIMAGE_ADDR, ((void*)lh) + real_mode_size, image_size - real_mode_size);
/*
* switch back to real mode now and start the real mode part of the
* image at address "(LINUX_OLD_REAL_MODE_ADDR >> 4) + 0x20:0x0000"
* which means "0x9020:0x000" -> 0x90200
*/
bios_start_linux(LINUX_OLD_REAL_MODE_SEGMT); /* does not return */
on_error:
if (lh != NULL)
free(lh);
return rc;
}
BAREBOX_CMD_HELP_START(linux16)
BAREBOX_CMD_HELP_USAGE("linux16 <file> [-v <mode>]\n")
BAREBOX_CMD_HELP_SHORT("Boot a kernel <file> on x86 via real mode code.\n")
BAREBOX_CMD_HELP_OPT ("-v <mode>", "VESA video mode number or 'ask'\n")
BAREBOX_CMD_HELP_END
/**
* @page linux16_command
<p>Only kernel images in bzImage format are supported by now. See \ref
x86_boot_preparation for more info about how to use this command.</p>
<p>For the video mode refer the Linux kernel documentation
'Documentation/fb/vesafb.txt' for correct VESA mode numbers. If the keyword
'ask' instead of a number is given, the starting kernel will ask for a number.
</p>
*/
BAREBOX_CMD_START(linux16)
.cmd = do_linux16,
.usage = "boot a linux kernel",
BAREBOX_CMD_HELP(cmd_linux16_help)
BAREBOX_CMD_END
/**
* @file
* @brief Boot support for Linux on x86
*/
/**
* @page x86_boot_preparation Linux Preparation on x86
*
* Due to some real mode constraints, starting Linux is somehow tricky.
* Currently only @p bzImages are supported, because @p zImages would
* interfere with the @a barebox runtime.
* Also older load header versions than 2.00 aren't supported.
*
* The memory layout immediately before starting the Linux kernel:
*
@verbatim
real mode space hole extended memory
|---------------------------------------------->|----------->|------------------------------>
0 0x7e00 0x90000 0xa0000 0x100000
<-1-|----------2-----------><-3- |
<-4--|-5--> |---------6------------->
@endverbatim
*
* @li 1 = @a barebox's real mode stack
* @li 2 = @a barebox's code
* @li 3 = @a barebox's flat mode stack
* @li 4 = real mode stack, when starting the Linux kernel
* @li 5 = Kernel's real mode setup code
* @li 6 = compressed kernel image
*
* A more detailed memory layout for kernel's real mode setup code
*
@verbatim
0x90000 0x97fff 0x99000 0x990ff
---|------------------------------------------|----------------|--------------------|
|<-------- max setup code size ----------->|<--heap/stack-->|<-- command line -->|
@endverbatim
*
* The regular entry point into the setup code is 0x90200 (2nd sector)
*
* To start the kernel, it's own setup code will be called. To do so, it
* must be called in real mode. So, @a barebox switches back to real mode
* a last time and does a jump to the setup code entry point. Now its up to
* the setup code to deflate the kernel, switching to its own protected mode
* setup and starting the kernel itself.
*
* @note This scenario only works, if a BIOS is still present. In this case
* there is no need for @a barebox to forward any system related information
* to the kernel. Everything is detected by kernel's setup code.
*
*/
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