[Qemu-devel] [PATCH 0/4] Add multiboot support (x86)

[Qemu-devel] [PATCH 0/4] Add multiboot support (x86)

[Alexander Graf]

This patch implements support for Multiboot on x86 for -kernel.
Multiboot is a "new" approach to get rid of different bootloaders, providing
a unified interface for the kernel. It supports command line options and
kernel modules.

The two probably best known projects using multiboot are Xen and GNU Hurd.

This implementation should be mostly feature-complete. It is missing VBE
extensions, but as no system uses them currently it does not really hurt.

To use multiboot, specify the kernel as -kernel option. Modules should be given
as -initrd options, seperated by a comma (,). -append also works.

Please bear in mind that grub also does gzip decompression, which qemu does
not do yet. To run existing images, please ungzip them first.

The guest multiboot loader code is implemented as option rom using int 19.
Parts of the work are based on efforts by Rene Rebe, who originally ported
my code to int 19.

Also, Kevin Wolf helped a lot whenever I had a new version of this patch
around.

Alexander Graf (4):
  Change bochs bios init order
  Expose fw_cfg
  Multiboot support
  Multiboot build system

 hw/pc.c                       |  241 ++++++++++++++++++++++++++++++++++++++---
 pc-bios/multiboot/Makefile    |   41 +++++++
 pc-bios/multiboot/multiboot.S |  229 +++++++++++++++++++++++++++++++++++++++
 pc-bios/multiboot/signrom.c   |   79 ++++++++++++++
 target-i386/cpu.h             |    3 +
 5 files changed, 577 insertions(+), 16 deletions(-)
 create mode 100644 pc-bios/multiboot/Makefile
 create mode 100644 pc-bios/multiboot/multiboot.S
 create mode 100644 pc-bios/multiboot/signrom.c

[Qemu-devel] [PATCH 1/4] Change bochs bios init order

[Alexander Graf]

For multiboot support, we need bochs_bios_init to happen before
load_linux, so we get the fw_cfg device.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 hw/pc.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/hw/pc.c b/hw/pc.c
index 143b697..f0df669 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -970,6 +970,12 @@ static void pc_init1(ram_addr_t ram_size,
     if (oprom_area_size < 0x8000)
         oprom_area_size = 0x8000;
 
+    /* map all the bios at the top of memory */
+    cpu_register_physical_memory((uint32_t)(-bios_size),
+                                 bios_size, bios_offset | IO_MEM_ROM);
+
+    bochs_bios_init();
+
     if (linux_boot) {
         load_linux(0xc0000 + oprom_area_size,
                    kernel_filename, initrd_filename, kernel_cmdline, below_4g_mem_size);
@@ -981,12 +987,6 @@ static void pc_init1(ram_addr_t ram_size,
                                            0xc0000 + oprom_area_size, 0xe0000);
     }
 
-    /* map all the bios at the top of memory */
-    cpu_register_physical_memory((uint32_t)(-bios_size),
-                                 bios_size, bios_offset | IO_MEM_ROM);
-
-    bochs_bios_init();
-
     cpu_irq = qemu_allocate_irqs(pic_irq_request, NULL, 1);
     i8259 = i8259_init(cpu_irq[0]);
     ferr_irq = i8259[13];
-- 
1.6.0.2

[Qemu-devel] [PATCH 2/4] Expose fw_cfg

[Alexander Graf]

Multiboot passes options to the option rom using the fw_cfg device.
Right now, that device is local to the bochs_bios_init function.

Let's change that and expose it to env, so everyone may put data
in there.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 hw/pc.c           |    8 +++++---
 target-i386/cpu.h |    3 +++
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/hw/pc.c b/hw/pc.c
index f0df669..171447e 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -448,7 +448,7 @@ static void bochs_bios_write(void *opaque, uint32_t addr, uint32_t val)
 
 extern uint64_t node_cpumask[MAX_NODES];
 
-static void bochs_bios_init(void)
+static void bochs_bios_init(CPUState *env)
 {
     void *fw_cfg;
     uint8_t *smbios_table;
@@ -468,6 +468,8 @@ static void bochs_bios_init(void)
     register_ioport_write(0x503, 1, 1, bochs_bios_write, NULL);
 
     fw_cfg = fw_cfg_init(BIOS_CFG_IOPORT, BIOS_CFG_IOPORT + 1, 0, 0);
+    env->fw_cfg = fw_cfg;
+
     fw_cfg_add_i32(fw_cfg, FW_CFG_ID, 1);
     fw_cfg_add_i64(fw_cfg, FW_CFG_RAM_SIZE, (uint64_t)ram_size);
     fw_cfg_add_bytes(fw_cfg, FW_CFG_ACPI_TABLES, (uint8_t *)acpi_tables,
@@ -849,7 +851,7 @@ static void pc_init1(ram_addr_t ram_size,
     int bios_size, isa_bios_size, oprom_area_size;
     PCIBus *pci_bus;
     int piix3_devfn = -1;
-    CPUState *env;
+    CPUState *env = NULL;
     qemu_irq *cpu_irq;
     qemu_irq *i8259;
     int index;
@@ -974,7 +976,7 @@ static void pc_init1(ram_addr_t ram_size,
     cpu_register_physical_memory((uint32_t)(-bios_size),
                                  bios_size, bios_offset | IO_MEM_ROM);
 
-    bochs_bios_init();
+    bochs_bios_init(env);
 
     if (linux_boot) {
         load_linux(0xc0000 + oprom_area_size,
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index d7b32d4..9fef0f7 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -676,6 +676,9 @@ typedef struct CPUX86State {
     /* in order to simplify APIC support, we leave this pointer to the
        user */
     struct APICState *apic_state;
+
+    /* Firmware configuration device */
+    void *fw_cfg;
 } CPUX86State;
 
 CPUX86State *cpu_x86_init(const char *cpu_model);
-- 
1.6.0.2

[Qemu-devel] [PATCH 3/4] Multiboot support

[Alexander Graf]

This patch implements support for Multiboot on x86 for -kernel.
Multiboot is a "new" approach to get rid of different bootloaders, providing
a unified interface for the kernel. It supports command line options and
kernel modules.

The two probably best known projects using multiboot are Xen and GNU Hurd.

This implementation should be mostly feature-complete. It is missing VBE
extensions, but as no system uses them currently it does not really hurt.

To use multiboot, specify the kernel as -kernel option. Modules should be given
as -initrd options, seperated by a comma (,). -append also works.

Please bear in mind that grub also does gzip decompression, which qemu does
not do yet. To run existing images, please ungzip them first.

The guest multiboot loader code is implemented as option rom using int 19.
Parts of the work are based on efforts by Rene Rebe, who originally ported
my code to int 19.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 hw/pc.c                       |  223 ++++++++++++++++++++++++++++++++++++++--
 pc-bios/multiboot/multiboot.S |  229 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 444 insertions(+), 8 deletions(-)
 create mode 100644 pc-bios/multiboot/multiboot.S

diff --git a/hw/pc.c b/hw/pc.c
index 171447e..608c433 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -40,6 +40,9 @@
 /* output Bochs bios info messages */
 //#define DEBUG_BIOS
 
+/* Show multiboot debug output */
+//#define DEBUG_MULTIBOOT
+
 #define BIOS_FILENAME "bios.bin"
 #define VGABIOS_FILENAME "vgabios.bin"
 #define VGABIOS_CIRRUS_FILENAME "vgabios-cirrus.bin"
@@ -595,7 +598,197 @@ static long get_file_size(FILE *f)
     return size;
 }
 
-static void load_linux(target_phys_addr_t option_rom,
+static int load_multiboot(CPUState *env,
+                          FILE *f,
+                          const char *kernel_filename,
+                          const char *initrd_filename,
+                          const char *kernel_cmdline,
+                          uint8_t *header)
+{
+    int i, is_multiboot = 0;
+    uint32_t flags = 0;
+    uint32_t mh_entry_addr;
+    uint32_t mh_load_addr;
+    uint32_t mb_kernel_size;
+    uint32_t mb_bootinfo = 0x90500;
+    uint32_t mmap_addr = 0x90000;
+
+    /* Ok, let's see if it is a multiboot image.
+       The header is 12x32bit long, so the latest entry may be 8192 - 48. */
+    for(i = 0; i < (8192 - 48); i += 4) {
+        if(ldl_p(header+i) == 0x1BADB002) {
+            uint32_t checksum = ldl_p(header+i+8);
+            flags = ldl_p(header+i+4);
+            checksum += flags;
+            checksum += (uint32_t)0x1BADB002;
+            if(!checksum) {
+                is_multiboot = 1;
+                break;
+            }
+        }
+    }
+
+    if(!is_multiboot)
+        return 0; /* no multiboot */
+
+#ifdef DEBUG_MULTIBOOT
+    fprintf(stderr, "qemu: I believe we found a multiboot image!\n");
+#endif
+
+    if(flags & 0x00000004) { /* MULTIBOOT_HEADER_HAS_VBE */
+        fprintf(stderr, "qemu: multiboot knows VBE. we don't.\n");
+    }
+    if(!(flags & 0x00010000)) { /* MULTIBOOT_HEADER_HAS_ADDR */
+        uint64_t elf_entry;
+        int kernel_size;
+        fclose(f);
+        kernel_size = load_elf(kernel_filename, 0, &elf_entry, NULL, NULL);
+        if(kernel_size < 0) {
+            fprintf(stderr, "Error while loading elf kernel\n");
+            exit(1);
+        }
+        mh_load_addr = mh_entry_addr = elf_entry;
+        mb_kernel_size = kernel_size;
+
+#ifdef DEBUG_MULTIBOOT
+        fprintf(stderr, "qemu: loading multiboot-elf kernel (%#x bytes) with entry %#zx\n",
+                mb_kernel_size, (size_t)mh_entry_addr);
+#endif
+    } else {
+        /* Valid if mh_flags sets MULTIBOOT_HEADER_HAS_ADDR. */
+        uint32_t mh_header_addr = ldl_p(header+i+12);
+        mh_load_addr = ldl_p(header+i+16);
+#ifdef DEBUG_MULTIBOOT
+        uint32_t mh_load_end_addr = ldl_p(header+i+20);
+        uint32_t mh_bss_end_addr = ldl_p(header+i+24);
+#endif
+        uint32_t mb_kernel_text_offset = i - (mh_header_addr - mh_load_addr);
+
+        mh_entry_addr = ldl_p(header+i+28);
+        mb_kernel_size = get_file_size(f) - mb_kernel_text_offset;
+
+        /* Valid if mh_flags sets MULTIBOOT_HEADER_HAS_VBE.
+        uint32_t mh_mode_type = ldl_p(header+i+32);
+        uint32_t mh_width = ldl_p(header+i+36);
+        uint32_t mh_height = ldl_p(header+i+40);
+        uint32_t mh_depth = ldl_p(header+i+44); */
+
+#ifdef DEBUG_MULTIBOOT
+        fprintf(stderr, "multiboot: mh_header_addr = %#x\n", mh_header_addr);
+        fprintf(stderr, "multiboot: mh_load_addr = %#x\n", mh_load_addr);
+        fprintf(stderr, "multiboot: mh_load_end_addr = %#x\n", mh_load_end_addr);
+        fprintf(stderr, "multiboot: mh_bss_end_addr = %#x\n", mh_bss_end_addr);
+#endif
+
+        fseek(f, mb_kernel_text_offset, SEEK_SET);
+
+#ifdef DEBUG_MULTIBOOT
+        fprintf(stderr, "qemu: loading multiboot kernel (%#x bytes) at %#x\n",
+                mb_kernel_size, mh_load_addr);
+#endif
+
+        if (!fread_targphys_ok(mh_load_addr, mb_kernel_size, f)) {
+            fprintf(stderr, "qemu: read error on multiboot kernel '%s' (%#x)\n",
+                    kernel_filename, mb_kernel_size);
+            exit(1);
+        }
+        fclose(f);
+    }
+
+
+    /* load modules */
+    stl_phys(mb_bootinfo + 20, 0x0); /* mods_count */
+    if(initrd_filename) {
+        uint32_t mb_mod_info = mb_bootinfo + 0x100;
+        uint32_t mb_mod_cmdline = mb_bootinfo + 0x300;
+        uint32_t mb_mod_start = mh_load_addr;
+        uint32_t mb_mod_length = mb_kernel_size;
+        char *next_initrd;
+        char *next_space;
+        int mb_mod_count = 0;
+
+        do {
+            next_initrd = strchr(initrd_filename, ',');
+            if(next_initrd)
+                *next_initrd = '\0';
+            /* if a space comes after the module filename, treat everything
+               after that as parameters */
+            cpu_physical_memory_write(mb_mod_cmdline, (uint8_t*)initrd_filename,
+                                      strlen(initrd_filename) + 1);
+            stl_phys(mb_mod_info + 8, mb_mod_cmdline); /* string */
+            mb_mod_cmdline += strlen(initrd_filename) + 1;
+            if((next_space = strchr(initrd_filename, ' ')))
+                *next_space = '\0';
+#ifdef DEBUG_MULTIBOOT
+	     printf("multiboot loading module: %s\n", initrd_filename);
+#endif
+            f = fopen(initrd_filename, "rb");
+            if(f) {
+                mb_mod_start = (mb_mod_start + mb_mod_length + (TARGET_PAGE_SIZE - 1))
+                             & (TARGET_PAGE_MASK);
+                mb_mod_length = get_file_size(f);
+
+                if (!fread_targphys_ok(mb_mod_start, mb_mod_length, f)) {
+                    fprintf(stderr, "qemu: read error on multiboot module '%s' (%#x)\n",
+                            initrd_filename, mb_mod_length);
+                    exit(1);
+                }
+
+                mb_mod_count++;
+                stl_phys(mb_mod_info + 0, mb_mod_start);
+                stl_phys(mb_mod_info + 4, mb_mod_start + mb_mod_length);
+#ifdef DEBUG_MULTIBOOT
+                printf("mod_start: %#x\nmod_end:   %#x\n", mb_mod_start,
+                       mb_mod_start + mb_mod_length);
+#endif
+                stl_phys(mb_mod_info + 12, 0x0); /* reserved */
+            }
+            initrd_filename = next_initrd+1;
+            mb_mod_info += 16;
+        } while(next_initrd);
+        stl_phys(mb_bootinfo + 20, mb_mod_count); /* mods_count */
+        stl_phys(mb_bootinfo + 24, mb_bootinfo + 0x100); /* mods_addr */
+    }
+
+    /* Commandline support */
+    stl_phys(mb_bootinfo + 16, mb_bootinfo + 0x200);
+    cpu_physical_memory_write(mb_bootinfo + 0x200, (uint8_t*)kernel_cmdline,
+                              strlen(kernel_cmdline) + 1);
+
+    /* the kernel is where we want it to be now */
+
+#define MULTIBOOT_FLAGS_MEMORY (1 << 0)
+#define MULTIBOOT_FLAGS_BOOT_DEVICE (1 << 1)
+#define MULTIBOOT_FLAGS_CMDLINE (1 << 2)
+#define MULTIBOOT_FLAGS_MODULES (1 << 3)
+#define MULTIBOOT_FLAGS_MMAP (1 << 6)
+    stl_phys(mb_bootinfo, MULTIBOOT_FLAGS_MEMORY
+                        | MULTIBOOT_FLAGS_BOOT_DEVICE
+                        | MULTIBOOT_FLAGS_CMDLINE
+                        | MULTIBOOT_FLAGS_MODULES
+                        | MULTIBOOT_FLAGS_MMAP);
+    stl_phys(mb_bootinfo + 4, 640); /* mem_lower */
+    stl_phys(mb_bootinfo + 8, ram_size / 1024); /* mem_upper */
+    stl_phys(mb_bootinfo + 12, 0x8001ffff); /* XXX: use the -boot switch? */
+    stl_phys(mb_bootinfo + 48, mmap_addr); /* mmap_addr */
+
+#ifdef DEBUG_MULTIBOOT
+    fprintf(stderr, "multiboot: mh_entry_addr = %#x\n", mh_entry_addr);
+#endif
+
+    /* Pass variables to option rom */
+    fw_cfg_add_i32(env->fw_cfg, FW_CFG_KERNEL_ADDR, mh_entry_addr);
+    fw_cfg_add_i32(env->fw_cfg, FW_CFG_INITRD_ADDR, mb_bootinfo);
+    fw_cfg_add_i32(env->fw_cfg, FW_CFG_INITRD_SIZE, mmap_addr);
+
+    option_rom[nb_option_roms] = "multiboot.bin";
+    nb_option_roms++;
+
+    return 1; /* yes, we are multiboot */
+}
+
+static void load_linux(CPUState *env,
+                       target_phys_addr_t option_rom,
                        const char *kernel_filename,
 		       const char *initrd_filename,
 		       const char *kernel_cmdline,
@@ -607,7 +798,7 @@ static void load_linux(target_phys_addr_t option_rom,
     uint16_t real_seg;
     int setup_size, kernel_size, initrd_size = 0, cmdline_size;
     uint32_t initrd_max;
-    uint8_t header[1024];
+    uint8_t header[8192];
     target_phys_addr_t real_addr, prot_addr, cmdline_addr, initrd_addr = 0;
     FILE *f, *fi;
 
@@ -617,7 +808,8 @@ static void load_linux(target_phys_addr_t option_rom,
     /* load the kernel header */
     f = fopen(kernel_filename, "rb");
     if (!f || !(kernel_size = get_file_size(f)) ||
-	fread(header, 1, 1024, f) != 1024) {
+	fread(header, 1, MIN(ARRAY_SIZE(header), kernel_size), f) !=
+	MIN(ARRAY_SIZE(header), kernel_size)) {
 	fprintf(stderr, "qemu: could not load kernel '%s'\n",
 		kernel_filename);
 	exit(1);
@@ -629,8 +821,14 @@ static void load_linux(target_phys_addr_t option_rom,
 #endif
     if (ldl_p(header+0x202) == 0x53726448)
 	protocol = lduw_p(header+0x206);
-    else
+    else {
+	/* This looks like a multiboot kernel. If it is, let's stop
+	   treating it like a Linux kernel. */
+	if (load_multiboot(env, f, kernel_filename,
+                           initrd_filename, kernel_cmdline, header))
+	   return;
 	protocol = 0;
+    }
 
     if (protocol < 0x200 || !(header[0x211] & 0x01)) {
 	/* Low kernel */
@@ -720,16 +918,25 @@ static void load_linux(target_phys_addr_t option_rom,
     }
 
     /* store the finalized header and load the rest of the kernel */
-    cpu_physical_memory_write(real_addr, header, 1024);
+    cpu_physical_memory_write(real_addr, header, ARRAY_SIZE(header));
 
     setup_size = header[0x1f1];
     if (setup_size == 0)
 	setup_size = 4;
 
     setup_size = (setup_size+1)*512;
-    kernel_size -= setup_size;	/* Size of protected-mode code */
+    /* Size of protected-mode code */
+    kernel_size -= (setup_size > ARRAY_SIZE(header)) ? setup_size : ARRAY_SIZE(header);
+
+    /* In case we have read too much already, copy that over */
+    if (setup_size < ARRAY_SIZE(header)) {
+        cpu_physical_memory_write(prot_addr, header + setup_size, ARRAY_SIZE(header) - setup_size);
+        prot_addr += (ARRAY_SIZE(header) - setup_size);
+        setup_size = ARRAY_SIZE(header);
+    }
 
-    if (!fread_targphys_ok(real_addr+1024, setup_size-1024, f) ||
+    if (!fread_targphys_ok(real_addr + ARRAY_SIZE(header),
+                           setup_size - ARRAY_SIZE(header), f) ||
 	!fread_targphys_ok(prot_addr, kernel_size, f)) {
 	fprintf(stderr, "qemu: read error on kernel '%s'\n",
 		kernel_filename);
@@ -979,7 +1186,7 @@ static void pc_init1(ram_addr_t ram_size,
     bochs_bios_init(env);
 
     if (linux_boot) {
-        load_linux(0xc0000 + oprom_area_size,
+        load_linux(env, 0xc0000 + oprom_area_size,
                    kernel_filename, initrd_filename, kernel_cmdline, below_4g_mem_size);
         oprom_area_size += 2048;
     }
diff --git a/pc-bios/multiboot/multiboot.S b/pc-bios/multiboot/multiboot.S
new file mode 100644
index 0000000..5a2acba
--- /dev/null
+++ b/pc-bios/multiboot/multiboot.S
@@ -0,0 +1,229 @@
+/*
+ * Multiboot Option ROM
+ *
+ * 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Copyright Novell Inc, 2009
+ *   Authors: Alexander Graf <agraf@suse.de>
+ */
+
+#define NO_QEMU_PROTOS
+#include "../../hw/fw_cfg.h"
+
+#define BIOS_CFG_IOPORT_CFG	0x510
+#define BIOS_CFG_IOPORT_DATA	0x511
+
+#define MULTIBOOT_MAGIC		0x2badb002
+
+/* Read a variable from the fw_cfg device.
+   Clobbers:	%edx
+   Out:		%eax */
+.macro read_fw VAR
+	mov		$\VAR, %ax
+	mov		$BIOS_CFG_IOPORT_CFG, %dx
+	outw		%ax, (%dx)
+	mov		$BIOS_CFG_IOPORT_DATA, %dx
+	inb		(%dx), %al
+	shl		$8, %eax
+	inb		(%dx), %al
+	shl		$8, %eax
+	inb		(%dx), %al
+	shl		$8, %eax
+	inb		(%dx), %al
+	bswap		%eax
+.endm
+
+.code16
+.text
+	.global 	_start
+_start:
+	.short		0xaa55
+	.byte		(_end - _start) / 512
+	push		%eax
+	push		%ds
+
+	/* setup ds so we can access the IVT */
+	xor		%ax, %ax
+	mov		%ax, %ds
+
+	/* save old int 19 */
+	mov		(0x19*4), %eax
+	mov		%eax, %cs:old_int19
+
+	/* install our int 19 handler */
+	movw		$int19_handler, (0x19*4)
+	mov		%cs, (0x19*4+2)
+
+	pop		%ds
+	pop		%eax
+	lret
+
+int19_handler:
+	/* DS = CS */
+	movw		%cs, %ax
+	movw		%ax, %ds
+
+	/* fall through */
+
+run_multiboot:
+
+	cli
+	cld
+
+	mov		%cs, %eax
+	shl		$0x4, %eax
+
+	/* fix the gdt descriptor to be PC relative */
+	mov		(gdt_desc+2), %ebx
+	add		%eax, %ebx
+	mov		%ebx, (gdt_desc+2)
+
+	/* fix the lgdt instruction to be PC relative */
+	mov		(lgdt + 5), %ebx
+	add		%eax, %ebx
+	mov		%ebx, (lgdt + 5)
+
+	/* fix the ljmp instructions to be PC relative */
+	mov		(ljmp + 4), %ebx
+	add		%eax, %ebx
+	mov		%ebx, (ljmp + 4)
+	mov		%ebx, (ljmp2 + 2)
+
+	/* get the indirect jump to prot mode PC relative */
+	mov		(prot_jump), %ebx
+	add		%eax, %ebx
+	mov		%ebx, (prot_jump)
+
+	/* fix mov to prot_jump in protected mode */
+	mov		(mov_pj + 1), %ebx
+	add		%eax, %ebx
+	mov		%ebx, (mov_pj + 1)
+
+	/* FS = bootinfo_struct */
+	read_fw		FW_CFG_INITRD_ADDR
+	shr		$4, %eax
+	mov		%ax, %fs
+
+	/* ES = mmap_addr */
+	read_fw		FW_CFG_INITRD_SIZE
+	shr		$4, %eax
+	mov		%ax, %es
+
+	/* Initialize multiboot mmap structs using int 0x15(e820) */
+	xor		%ebx, %ebx
+	/* mmap start after first size */
+	movl		$4, %edi
+
+mmap_loop:
+	/* entry size (mmap struct) & max buffer size (int15) */
+	movl		$20, %ecx
+	/* store entry size */
+	movl		%ecx, %es:-4(%edi)
+	/* e820 */
+	movl		$0x0000e820, %eax
+	/* 'SMAP' magic */
+	movl		$0x534d4150, %edx
+	int		$0x15
+
+mmap_check_entry:
+	/* last entry? then we're done */
+	jb		mmap_done
+	and		%bx, %bx
+	jz		mmap_done
+	/* valid entry, so let's loop on */
+
+mmap_store_entry:
+	/* %ax = entry_number * 24 */
+	mov		$24, %ax
+	mul		%bx
+	mov		%ax, %di
+	movw		%di, %fs:0x2c
+	/* %di = 4 + (entry_number * 24) */
+	add		$4, %di
+	jmp		mmap_loop
+
+mmap_done:
+real_to_prot:
+	/* get us to protected mode now */
+	movl		$1, %eax
+	movl		%eax, %cr0
+
+	/* Load the GDT before going into protected mode */
+	xor		%bx, %bx
+	mov		%bx, %ds
+lgdt:
+	addr32 data32 lgdt	(gdt_desc)
+
+	/* the LJMP sets CS for us and gets us to 32-bit */
+ljmp:
+	addr32 data32 ljmp	*(prot_jump)
+
+prot_mode:
+.code32
+
+	/* initialize all other segments */
+	movl		$0x10, %eax
+	movl		%eax, %ss
+	movl		%eax, %ds
+	movl		%eax, %es
+	movl		%eax, %fs
+	movl		%eax, %gs
+
+	/* Jump off to the kernel */
+	read_fw		FW_CFG_KERNEL_ADDR
+mov_pj:
+	mov		%eax, (prot_jump)
+
+	/* EBX contains a pointer to the bootinfo struct */
+	read_fw		FW_CFG_INITRD_ADDR
+	movl		%eax, %ebx
+
+	/* EAX has to contain the magic */
+	movl		$MULTIBOOT_MAGIC, %eax
+ljmp2:
+	ljmp		*(prot_jump)
+
+/* Variables */
+.align 4, 0
+old_int19:	.long 0
+
+.align 4, 0
+gdt:
+	/* 0x00 */
+.byte	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+
+	/* 0x08: code segment (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k) */
+.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00
+
+	/* 0x10: data segment (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k) */
+.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00
+
+	/* 0x18: code segment (base=0, limit=0x0ffff, type=16bit code exec/read/conf, DPL=0, 1b) */
+.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x9e, 0x00, 0x00
+
+	/* 0x20: data segment (base=0, limit=0x0ffff, type=16bit data read/write, DPL=0, 1b) */
+.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0x00, 0x00
+
+gdt_desc:
+.short	(5 * 8) - 1
+.long	gdt
+
+prot_jump:
+.long	prot_mode
+.short	0x8
+
+.align 512, 0
+_end:
+
-- 
1.6.0.2

[Qemu-devel] [PATCH 4/4] Multiboot build system

[Alexander Graf]

In order to build the multiboot option rom, we need a Makefile and a tool
to sign the rom with.

Both are provided by this patch and mostly taken from the extboot source,
written by Anthony Liguori.

Once built, please copy the multiboot.bin file to your pc-bios directory
to actually be able to use the option rom.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 pc-bios/multiboot/Makefile  |   41 ++++++++++++++++++++++
 pc-bios/multiboot/signrom.c |   79 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 120 insertions(+), 0 deletions(-)
 create mode 100644 pc-bios/multiboot/Makefile
 create mode 100644 pc-bios/multiboot/signrom.c

diff --git a/pc-bios/multiboot/Makefile b/pc-bios/multiboot/Makefile
new file mode 100644
index 0000000..0e7a764
--- /dev/null
+++ b/pc-bios/multiboot/Makefile
@@ -0,0 +1,41 @@
+OBJCOPY=objcopy
+
+# from kernel sources - scripts/Kbuild.include
+# try-run
+# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
+# Exit code chooses option. "$$TMP" is can be used as temporary file and
+# is automatically cleaned up.
+try-run = $(shell set -e;		\
+	TMP="$(TMPOUT).$$$$.tmp";	\
+	if ($(1)) >/dev/null 2>&1;	\
+	then echo "$(2)";		\
+	else echo "$(3)";		\
+	fi;				\
+	rm -f "$$TMP")
+
+# cc-option-yn
+# Usage: flag := $(call cc-option-yn,-march=winchip-c6)
+cc-option-yn = $(call try-run,\
+	$(CC) $(KBUILD_CFLAGS) $(1) -S -xc /dev/null -o "$$TMP",y,n)
+
+CFLAGS = -Wall -Wstrict-prototypes -Werror -fomit-frame-pointer -fno-builtin
+ifeq ($(call cc-option-yn,-fno-stack-protector),y)
+CFLAGS += -fno-stack-protector
+endif
+
+all: multiboot.bin
+
+%.o: %.S
+	$(CC) $(CFLAGS) -o $@ -c $<
+
+multiboot.img: multiboot.o
+	$(LD) --oformat binary -Ttext 0 -o $@ $<
+
+multiboot.bin: multiboot.img signrom
+	./signrom multiboot.img multiboot.bin
+
+signrom: signrom.c
+	$(CC) -o $@ -g -Wall $^
+
+clean:
+	$(RM) *.o *.img *.bin signrom *~
diff --git a/pc-bios/multiboot/signrom.c b/pc-bios/multiboot/signrom.c
new file mode 100644
index 0000000..fe8d677
--- /dev/null
+++ b/pc-bios/multiboot/signrom.c
@@ -0,0 +1,79 @@
+/*
+ * Extended Boot Option ROM
+ *
+ * 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Copyright IBM Corporation, 2007
+ *   Authors: Anthony Liguori <aliguori@us.ibm.com>
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+int main(int argc, char **argv)
+{
+	FILE *fin, *fout;
+	char buffer[512], oldbuffer[512];
+	int i, size, lag = 0;
+	uint8_t sum = 0;
+
+	if (argc != 3) {
+		printf("Usage: %s ROM OUTPUT\n", argv[0]);
+		return 1;
+	}
+
+	fin = fopen(argv[1], "rb");
+	fout = fopen(argv[2], "wb");
+
+	if (fin == NULL || fout == NULL) {
+		fprintf(stderr, "Could not open input/output files\n");
+		return 1;
+	}
+
+	do {
+		size = fread(buffer, 512, 1, fin);
+		if (size == 1) {
+			for (i = 0; i < 512; i++)
+				sum += buffer[i];
+
+			if (lag) {
+				if (fwrite(oldbuffer, 512, 1, fout) != 1) {
+					fprintf(stderr, "Write failed\n");
+					return 1;
+				}
+			}
+			lag = 1;
+			memcpy(oldbuffer, buffer, 512);
+		}
+	} while (size == 1);
+
+	if (size != 0) {
+		fprintf(stderr, "Failed to read from input file\n");
+		return 1;
+	}
+
+	oldbuffer[511] = -sum;
+
+	if (fwrite(oldbuffer, 512, 1, fout) != 1) {
+		fprintf(stderr, "Failed to write to output file\n");
+		return 1;
+	}
+
+	fclose(fin);
+	fclose(fout);
+
+	return 0;
+}
-- 
1.6.0.2

Re: [Qemu-devel] [PATCH 4/4] Multiboot build system

[Paul Brook]

On Wednesday 17 June 2009, Alexander Graf wrote:
> In order to build the multiboot option rom, we need a Makefile and a tool
> to sign the rom with.

This appears to assume $(CC) is a useful i386 compiler (or assembler), and 
that your object file contains no relocations. The former is not all that 
likely, and the latter is very fragile.

Paul

Re: [Qemu-devel] [PATCH 4/4] Multiboot build system

[Alexander Graf]

On 17.06.2009, at 17:16, Paul Brook wrote:

> On Wednesday 17 June 2009, Alexander Graf wrote:
>> In order to build the multiboot option rom, we need a Makefile and  
>> a tool
>> to sign the rom with.
>
> This appears to assume $(CC) is a useful i386 compiler (or  
> assembler), and
> that your object file contains no relocations. The former is not all  
> that
> likely, and the latter is very fragile.

Yes, which is why you're only supposed to compile this on an i386  
machine and the resulting binary should be pushed to pc-bios by  
whoever commits this.

Isn't that the same as all the rest in pc-bios? Well - with the  
exception that this time we have the source and not only some  
patches ;-).

The relocations are always an issue. If you know about a magic  
compiler option that tells the compiler "scream of you find  
relocations", please tell me.

Alex

Re: [Qemu-devel] [PATCH 2/4] Expose fw_cfg

[Blue Swirl]

On 6/17/09, Alexander Graf <agraf@suse.de> wrote:
> Multiboot passes options to the option rom using the fw_cfg device.
>  Right now, that device is local to the bochs_bios_init function.
>
>  Let's change that and expose it to env, so everyone may put data
>  in there.

Env is a wrong place for device data.

Re: [Qemu-devel] [PATCH 2/4] Expose fw_cfg

[Alexander Graf]

On 17.06.2009, at 17:30, Blue Swirl wrote:

> On 6/17/09, Alexander Graf <agraf@suse.de> wrote:
>> Multiboot passes options to the option rom using the fw_cfg device.
>> Right now, that device is local to the bochs_bios_init function.
>>
>> Let's change that and expose it to env, so everyone may put data
>> in there.
>
> Env is a wrong place for device data.

So what is the right place? Last time I checked there wasn't anything  
like a global pc machine state struct, but I could be wrong.

Alex

Re: [Qemu-devel] [PATCH 2/4] Expose fw_cfg

[Anthony Liguori]

Alexander Graf wrote:
>
> On 17.06.2009, at 17:30, Blue Swirl wrote:
>
>> On 6/17/09, Alexander Graf <agraf@suse.de> wrote:
>>> Multiboot passes options to the option rom using the fw_cfg device.
>>> Right now, that device is local to the bochs_bios_init function.
>>>
>>> Let's change that and expose it to env, so everyone may put data
>>> in there.
>>
>> Env is a wrong place for device data.
>
> So what is the right place? Last time I checked there wasn't anything 
> like a global pc machine state struct, but I could be wrong.

Return fw_cfg from bochs_bios_init, then pass it to the kernel loading 
functions.

Regards,

Anthony Liguori

> Alex
>
>

[Qemu-devel] Re: [PATCH 4/4] Multiboot build system

[Paolo Bonzini]

> The relocations are always an issue. If you know about a magic compiler 
> option that tells the compiler "scream of you find relocations", please 
> tell me.

You can do a normal ELF link and use readelf on the output.

Paolo

[Qemu-devel] Re: [PATCH 4/4] Multiboot build system

[Alexander Graf]

On 18.06.2009, at 09:57, Paolo Bonzini wrote:

>
>> The relocations are always an issue. If you know about a magic  
>> compiler option that tells the compiler "scream of you find  
>> relocations", please tell me.
>
> You can do a normal ELF link and use readelf on the output.

Hm I just tried to put in an external relocation (mov %eax, FOO) and  
ld already complained about it.
What issue exactly were you talking about Paul?

Alex

Re: [Qemu-devel] Re: [PATCH 4/4] Multiboot build system

[Paolo Bonzini]

>>> The relocations are always an issue. If you know about a magic 
>>> compiler option that tells the compiler "scream of you find 
>>> relocations", please tell me.
>>
>> You can do a normal ELF link and use readelf on the output.
> 
> Hm I just tried to put in an external relocation (mov %eax, FOO) and ld 
> already complained about it.
> What issue exactly were you talking about Paul?

Just in case you were confusing Paolo B. (me) with Paul B., my 
suggestion was just a way to find relocations assuming ld would not 
complain.  Possibly Paul's (his) observation does not apply to binary 
output.

Paolo