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@xxxxxxxxxxxxxx>
---
Documentation/commands.dox | 2
arch/x86/include/asm/syslib.h | 4
arch/x86/lib/Makefile | 1
arch/x86/lib/linux_start.S | 75 ++++++++
commands/Kconfig | 8
commands/Makefile | 1
commands/linux16.c | 363 ++++++++++++++++++++++++++++++++++++++++++
7 files changed, 453 insertions(+), 1 deletion(-)
Index: u-boot-2.0.0-rc10/commands/Kconfig
===================================================================
--- u-boot-2.0.0-rc10.orig/commands/Kconfig
+++ u-boot-2.0.0-rc10/commands/Kconfig
@@ -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"
Index: u-boot-2.0.0-rc10/commands/Makefile
===================================================================
--- u-boot-2.0.0-rc10.orig/commands/Makefile
+++ u-boot-2.0.0-rc10/commands/Makefile
@@ -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
Index: u-boot-2.0.0-rc10/commands/linux16.c
===================================================================
--- /dev/null
+++ u-boot-2.0.0-rc10/commands/linux16.c
@@ -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";
+
+
+U_BOOT_CMD_START(linux16)
+ .cmd = do_linux16,
+ .usage = "boot linux kernel",
+ U_BOOT_CMD_HELP(cmd_linux16_help)
+U_BOOT_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.
+ *
+ */
Index: u-boot-2.0.0-rc10/arch/x86/include/asm/syslib.h
===================================================================
--- u-boot-2.0.0-rc10.orig/arch/x86/include/asm/syslib.h
+++ u-boot-2.0.0-rc10/arch/x86/include/asm/syslib.h
@@ -27,3 +27,7 @@ extern int bios_disk_rw_int13_extensions
extern uint16_t bios_get_memsize(void);
#endif
+
+#ifdef CONFIG_CMD_LINUX16
+extern void bios_start_linux(unsigned) __attribute__((regparm(1)));
+#endif
Index: u-boot-2.0.0-rc10/arch/x86/lib/Makefile
===================================================================
--- u-boot-2.0.0-rc10.orig/arch/x86/lib/Makefile
+++ u-boot-2.0.0-rc10/arch/x86/lib/Makefile
@@ -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
Index: u-boot-2.0.0-rc10/arch/x86/lib/linux_start.S
===================================================================
--- /dev/null
+++ u-boot-2.0.0-rc10/arch/x86/lib/linux_start.S
@@ -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
Index: u-boot-2.0.0-rc10/Documentation/commands.dox
===================================================================
--- u-boot-2.0.0-rc10.orig/Documentation/commands.dox
+++ u-boot-2.0.0-rc10/Documentation/commands.dox
@@ -20,5 +20,5 @@
@li @subpage setenv_command
@li @subpage sh_command
@li @subpage unprotect_command
-
+@li @subpage linux16_command
*/
--
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