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Add a special command to load and start a bzImage on x86 

Other architectures are supporting the uImage format used by barebox's 'bootm'
command. x86 does'nt. So, we need a special command to be able to boot the
x86 specific bzImage format.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Juergen Beisert 2010-01-12 11:15:47 +01:00 committed by Sascha Hauer
parent 835aa6b599
commit 7081093531
7 changed files with 453 additions and 1 deletions
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2
Documentation/commands.dox
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@ -20,5 +20,5 @@
@li @subpage setenv_command
@li @subpage sh_command
@li @subpage unprotect_command
@li @subpage linux16_command
*/

4
arch/x86/include/asm/syslib.h
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@ -27,3 +27,7 @@ extern int bios_disk_rw_int13_extensions(int, int, void*) __attribute__((regparm
extern uint16_t bios_get_memsize(void);
#endif
#ifdef CONFIG_CMD_LINUX16
extern void bios_start_linux(unsigned) __attribute__((regparm(1)));
#endif

1
arch/x86/lib/Makefile
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@ -6,3 +6,4 @@ obj-y += gdt.o
obj-$(CONFIG_X86_BIOS_BRINGUP) += memory16.o
obj-$(CONFIG_X86_BIOS_BRINGUP) += traveler.o
obj-$(CONFIG_X86_BIOS_BRINGUP) += bios_disk.o
obj-$(CONFIG_CMD_LINUX16) += linux_start.o

75
arch/x86/lib/linux_start.S Normal file
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@ -0,0 +1,75 @@
/*
* Copyright (C) 2009 Juergen Beisert, Pengutronix
*
* Mostly stolen from the GRUB2 project
* Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2006,2007,2008 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
*
*/
/**
* @file
* @brief Start the Linux real mode setup code
*
* Note: These functions are running in flat and real mode. Due to some
* other restrictions these routines must running from an address
* space below 0x10000
*/
/*
* void bios_start_linux(unsigned segment)
*
*/
#ifndef DOXYGEN_SHOULD_SKIP_THIS
.section .boot.text.bios_start_linux, "ax"
.code32
.globl bios_start_linux
.type bios_start_linux, @function
.extern prot_to_real
bios_start_linux:
/* 'prot_to_real' eats our eax content */
movl %eax, %ebx
addl $0x20, %eax
movw %ax, setup_seg
call prot_to_real
.code16
cli
/* all segment registers are using the same segment */
movw %bx, %ss
movw %bx, %ds
movw %bx, %es
movw %bx, %fs
movw %bx, %gs
/* stack for the setup code (end of heap) */
movw $0x9000, %sp
/* do an 'ljmp' and never return */
.byte 0xea
.word 0
setup_seg:
.word 0
.code32
#endif

8
commands/Kconfig
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@ -219,6 +219,14 @@ config CMD_BOOTU
compile in the 'bootu' command to start raw (uncompressed)
Linux images
config CMD_LINUX16
tristate
default y if X86
prompt "linux16"
help
Compile the linux16 command to be able to boot bzImages
via real mode.
config CMD_RESET
tristate
prompt "reset"

1
commands/Makefile
View File

@ -1,4 +1,5 @@
obj-$(CONFIG_CMD_BOOTM) += bootm.o
obj-$(CONFIG_CMD_LINUX16) += linux16.o
obj-$(CONFIG_CMD_LOADB) += loadb.o xyzModem.o
obj-$(CONFIG_CMD_LOADY) += loadb.o xyzModem.o
obj-$(CONFIG_CMD_LOADS) += loads.o

363
commands/linux16.c Normal file
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@ -0,0 +1,363 @@
/*
* 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 <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));
/**
* Load an x86 Linux kernel bzImage and start it
* @param cmdtp FIXME
* @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(cmd_tbl_t *cmdtp, int argc, char *argv[])
{
struct linux_kernel_header *lh = NULL;
int rc;
unsigned setup_sects;
unsigned real_mode_size;
size_t image_size;
const char *cmdline = getenv("bootargs");
if (argc < 2) {
perror("linux16");
return 1;
}
lh = read_file(argv[1], &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;
}
/* 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", 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;
}
static const __maybe_unused char cmd_linux16_help[] =
"Usage: linux16 <file>\n"
"Boot a linux kernel via real mode code\n";
BAREBOX_CMD_START(linux16)
.cmd = do_linux16,
.usage = "boot linux kernel",
BAREBOX_CMD_HELP(cmd_linux16_help)
BAREBOX_CMD_END
/**
* @file
* @brief Boot support for Linux on x86
*/
/**
* @page linux16_command linux16: Boot a bzImage kernel on x86
*
* Usage is: linux16 \<file\>
*
* Boot a linux kernel via real mode code. Only kernel images in the
* @p bzImage format are supported.
*/
/**
* @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.
*
*/