Patchwork [2/2] multiboot: Support arbitrary number of modules

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Submitter Adam Lackorzynski
Date Nov. 30, 2009, 10:26 p.m.
Message ID <20091130222650.GB21068@os.inf.tu-dresden.de>
Download mbox | patch
Permalink /patch/39864/
State New
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Comments

Adam Lackorzynski - Nov. 30, 2009, 10:26 p.m.
multiboot: Support arbitrary number of modules


Signed-off-by: Adam Lackorzynski <adam@os.inf.tu-dresden.de>
---
 hw/pc.c |  216 +++++++++++++++++++++++++++++++++++++++++---------------------
 1 files changed, 143 insertions(+), 73 deletions(-)
Alexander Graf - Dec. 1, 2009, 6:51 a.m.
On 30.11.2009, at 23:26, Adam Lackorzynski wrote:

> multiboot: Support arbitrary number of modules

Sounds like it's about time to extract the multiboot code from pc.c and move it to multiboot.c. After all, multiboot is supported on non-x86 as well, so maybe we can reuse some code here.

Alex
Anthony Liguori - Dec. 3, 2009, 8:26 p.m.
Adam Lackorzynski wrote:
> multiboot: Support arbitrary number of modules
>
>
> Signed-off-by: Adam Lackorzynski <adam@os.inf.tu-dresden.de>
> ---
>  hw/pc.c |  216 +++++++++++++++++++++++++++++++++++++++++---------------------
>  1 files changed, 143 insertions(+), 73 deletions(-)
>
> diff --git a/hw/pc.c b/hw/pc.c
> index 6bcfe1b..163bec1 100644
> --- a/hw/pc.c
> +++ b/hw/pc.c
> @@ -507,6 +507,79 @@ static long get_file_size(FILE *f)
>  #error multiboot struct needs to fit in 16 bit real mode
>  #endif
>  
> +enum {
> +    /* Multiboot info */
> +    MBI_FLAGS       = 0,
> +    MBI_MEM_LOWER   = 4,
> +    MBI_MEM_UPPER   = 8,
> +    MBI_BOOT_DEVICE = 12,
> +    MBI_CMDLINE     = 16,
> +    MBI_MODS_COUNT  = 20,
> +    MBI_MODS_ADDR   = 24,
> +    MBI_MMAP_ADDR   = 48,
> +
> +    MBI_SIZE        = 88,
> +
> +    /* Multiboot modules */
> +    MB_MOD_START    = 0,
> +    MB_MOD_END      = 4,
> +    MB_MOD_CMDLINE  = 8,
> +
> +    MB_MOD_SIZE     = 16,
> +
> +    /* Region offsets */
> +    ADDR_E820_MAP = MULTIBOOT_STRUCT_ADDR + 0,
> +    ADDR_MBI      = ADDR_E820_MAP + 0x500,
> +
> +    /* Multiboot flags */
> +    MULTIBOOT_FLAGS_MEMORY      = 1 << 0,
> +    MULTIBOOT_FLAGS_BOOT_DEVICE = 1 << 1,
> +    MULTIBOOT_FLAGS_CMDLINE     = 1 << 2,
> +    MULTIBOOT_FLAGS_MODULES     = 1 << 3,
> +    MULTIBOOT_FLAGS_MMAP        = 1 << 6,
> +};
> +
> +struct mb_state {
> +    void *mb_buf;         /* buffer holding kernel, cmdlines and mb_infos */
> +    uint32_t mb_buf_phys; /* address in target */
> +    int mb_buf_size;      /* size of mb_buf in bytes */
> +    int mb_mods_avail;    /* available slots for mb modules infos */
> +    int mb_mods_count;    /* currently used slots of mb modules */
> +    int offset_mbinfo;    /* offset of mb-info's in bytes */
> +    int offset_cmdlines;  /* offset in buffer for cmdlines */
> +    int offset_mods;      /* offset of modules in bytes */
> +};
>   

Should be MultibootState.

> +static uint32_t mb_add_cmdline(struct mb_state *s, const char *cmdline)
> +{
> +    int len = strlen(cmdline) + 1;
> +    uint32_t p = s->offset_cmdlines;
> +
> +    pstrcpy((char *)s->mb_buf + p, len, cmdline);
> +    s->offset_cmdlines += len;
> +    return s->mb_buf_phys + p;
> +}
> +
> +static void mb_add_mod(struct mb_state *s,
> +                       uint32_t start, uint32_t end,
> +                       uint32_t cmdline_phys)
> +{
> +    char *p;
> +    assert(s->mb_mods_count < s->mb_mods_avail);
> +
> +    p = (char *)s->mb_buf + s->offset_mbinfo + MB_MOD_SIZE * s->mb_mods_count;
> +
> +    stl_p(p + MB_MOD_START,   start);
> +    stl_p(p + MB_MOD_END,     end);
> +    stl_p(p + MB_MOD_CMDLINE, cmdline_phys);
> +
> +#ifdef DEBUG_MULTIBOOT
> +    fprintf(stderr, "mod%02d: %08x - %08x\n", s->mb_mods_count, start, end);
> +#endif
>   

A debug macro would be a lot nicer.

> +    s->mb_mods_count++;
> +}
> +
>  static int load_multiboot(void *fw_cfg,
>                            FILE *f,
>                            const char *kernel_filename,
> @@ -519,12 +592,8 @@ static int load_multiboot(void *fw_cfg,
>      uint32_t mh_entry_addr;
>      uint32_t mh_load_addr;
>      uint32_t mb_kernel_size;
> -    uint32_t mmap_addr = MULTIBOOT_STRUCT_ADDR;
> -    uint32_t mb_bootinfo = MULTIBOOT_STRUCT_ADDR + 0x500;
> -    uint32_t mb_mod_end;
> -    uint8_t bootinfo[0x500];
> -    uint32_t cmdline = 0x200;
> -    uint8_t *mb_kernel_data;
> +    struct mb_state mbs;
> +    uint8_t bootinfo[MBI_SIZE];
>      uint8_t *mb_bootinfo_data;
>  
>      /* Ok, let's see if it is a multiboot image.
> @@ -549,6 +618,7 @@ static int load_multiboot(void *fw_cfg,
>      fprintf(stderr, "qemu: I believe we found a multiboot image!\n");
>  #endif
>      memset(bootinfo, 0, sizeof(bootinfo));
> +    memset(&mbs, 0, sizeof(mbs));
>  
>      if (flags & 0x00000004) { /* MULTIBOOT_HEADER_HAS_VBE */
>          fprintf(stderr, "qemu: multiboot knows VBE. we don't.\n");
> @@ -566,8 +636,8 @@ static int load_multiboot(void *fw_cfg,
>          mh_load_addr = mh_entry_addr = elf_entry;
>          mb_kernel_size = kernel_size;
>  
> -        mb_kernel_data = qemu_malloc(mb_kernel_size);
> -        if (rom_copy(mb_kernel_data, elf_entry, kernel_size) != kernel_size) {
> +        mbs.mb_buf = qemu_malloc(mb_kernel_size);
> +        if (rom_copy(mbs.mb_buf, elf_entry, kernel_size) != kernel_size) {
>              fprintf(stderr, "Error while fetching elf kernel from rom\n");
>              exit(1);
>          }
> @@ -604,104 +674,104 @@ static int load_multiboot(void *fw_cfg,
>                  mb_kernel_size, mh_load_addr);
>  #endif
>  
> -        mb_kernel_data = qemu_malloc(mb_kernel_size);
> +        mbs.mb_buf = qemu_malloc(mb_kernel_size);
>          fseek(f, mb_kernel_text_offset, SEEK_SET);
> -        fread(mb_kernel_data, 1, mb_kernel_size, f);
> +        fread(mbs.mb_buf, 1, mb_kernel_size, f);
>          fclose(f);
>      }
>  
> -    /* blob size is only the kernel for now */
> -    mb_mod_end = mh_load_addr + mb_kernel_size;
> +    mbs.mb_buf_phys = mh_load_addr;
> +
> +    mbs.mb_buf_size = TARGET_PAGE_ALIGN(mb_kernel_size);
> +    mbs.offset_mbinfo = mbs.mb_buf_size;
> +
> +    /* Calculate space for cmdlines and mb_mods */
> +    mbs.mb_buf_size += strlen(kernel_filename) + 1;
> +    mbs.mb_buf_size += strlen(kernel_cmdline) + 1;
> +    if (initrd_filename) {
> +        const char *r = initrd_filename;
> +        mbs.mb_buf_size += strlen(r) + 1;
> +        mbs.mb_mods_avail = 1;
> +        while ((r = strchr(r, ','))) {
> +           mbs.mb_mods_avail++;
> +           r++;
> +        }
> +        mbs.mb_buf_size += MB_MOD_SIZE * mbs.mb_mods_avail;
> +    }
> +
> +    mbs.mb_buf_size = TARGET_PAGE_ALIGN(mbs.mb_buf_size);
> +
> +    // enlarge mb_buf to hold cmdlines and mb-info structs
>   

Please avoid C99 comments.

> +
> +	    mbs.mb_buf_size = TARGET_PAGE_ALIGN(mb_mod_length + mbs.mb_buf_size);
> +	    mbs.mb_buf = qemu_realloc(mbs.mb_buf, mbs.mb_buf_size);
> +
> +            load_image(initrd_filename, (unsigned char *)mbs.mb_buf + offs);
> +            mb_add_mod(&mbs, mbs.mb_buf_phys + offs,
> +                       mbs.mb_buf_phys + offs + mb_mod_length, c);
>   

You've got a mix of tabs and spaces.

Regards,

Anthony Liguori

Patch

diff --git a/hw/pc.c b/hw/pc.c
index 6bcfe1b..163bec1 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -507,6 +507,79 @@  static long get_file_size(FILE *f)
 #error multiboot struct needs to fit in 16 bit real mode
 #endif
 
+enum {
+    /* Multiboot info */
+    MBI_FLAGS       = 0,
+    MBI_MEM_LOWER   = 4,
+    MBI_MEM_UPPER   = 8,
+    MBI_BOOT_DEVICE = 12,
+    MBI_CMDLINE     = 16,
+    MBI_MODS_COUNT  = 20,
+    MBI_MODS_ADDR   = 24,
+    MBI_MMAP_ADDR   = 48,
+
+    MBI_SIZE        = 88,
+
+    /* Multiboot modules */
+    MB_MOD_START    = 0,
+    MB_MOD_END      = 4,
+    MB_MOD_CMDLINE  = 8,
+
+    MB_MOD_SIZE     = 16,
+
+    /* Region offsets */
+    ADDR_E820_MAP = MULTIBOOT_STRUCT_ADDR + 0,
+    ADDR_MBI      = ADDR_E820_MAP + 0x500,
+
+    /* Multiboot flags */
+    MULTIBOOT_FLAGS_MEMORY      = 1 << 0,
+    MULTIBOOT_FLAGS_BOOT_DEVICE = 1 << 1,
+    MULTIBOOT_FLAGS_CMDLINE     = 1 << 2,
+    MULTIBOOT_FLAGS_MODULES     = 1 << 3,
+    MULTIBOOT_FLAGS_MMAP        = 1 << 6,
+};
+
+struct mb_state {
+    void *mb_buf;         /* buffer holding kernel, cmdlines and mb_infos */
+    uint32_t mb_buf_phys; /* address in target */
+    int mb_buf_size;      /* size of mb_buf in bytes */
+    int mb_mods_avail;    /* available slots for mb modules infos */
+    int mb_mods_count;    /* currently used slots of mb modules */
+    int offset_mbinfo;    /* offset of mb-info's in bytes */
+    int offset_cmdlines;  /* offset in buffer for cmdlines */
+    int offset_mods;      /* offset of modules in bytes */
+};
+
+static uint32_t mb_add_cmdline(struct mb_state *s, const char *cmdline)
+{
+    int len = strlen(cmdline) + 1;
+    uint32_t p = s->offset_cmdlines;
+
+    pstrcpy((char *)s->mb_buf + p, len, cmdline);
+    s->offset_cmdlines += len;
+    return s->mb_buf_phys + p;
+}
+
+static void mb_add_mod(struct mb_state *s,
+                       uint32_t start, uint32_t end,
+                       uint32_t cmdline_phys)
+{
+    char *p;
+    assert(s->mb_mods_count < s->mb_mods_avail);
+
+    p = (char *)s->mb_buf + s->offset_mbinfo + MB_MOD_SIZE * s->mb_mods_count;
+
+    stl_p(p + MB_MOD_START,   start);
+    stl_p(p + MB_MOD_END,     end);
+    stl_p(p + MB_MOD_CMDLINE, cmdline_phys);
+
+#ifdef DEBUG_MULTIBOOT
+    fprintf(stderr, "mod%02d: %08x - %08x\n", s->mb_mods_count, start, end);
+#endif
+
+    s->mb_mods_count++;
+}
+
 static int load_multiboot(void *fw_cfg,
                           FILE *f,
                           const char *kernel_filename,
@@ -519,12 +592,8 @@  static int load_multiboot(void *fw_cfg,
     uint32_t mh_entry_addr;
     uint32_t mh_load_addr;
     uint32_t mb_kernel_size;
-    uint32_t mmap_addr = MULTIBOOT_STRUCT_ADDR;
-    uint32_t mb_bootinfo = MULTIBOOT_STRUCT_ADDR + 0x500;
-    uint32_t mb_mod_end;
-    uint8_t bootinfo[0x500];
-    uint32_t cmdline = 0x200;
-    uint8_t *mb_kernel_data;
+    struct mb_state mbs;
+    uint8_t bootinfo[MBI_SIZE];
     uint8_t *mb_bootinfo_data;
 
     /* Ok, let's see if it is a multiboot image.
@@ -549,6 +618,7 @@  static int load_multiboot(void *fw_cfg,
     fprintf(stderr, "qemu: I believe we found a multiboot image!\n");
 #endif
     memset(bootinfo, 0, sizeof(bootinfo));
+    memset(&mbs, 0, sizeof(mbs));
 
     if (flags & 0x00000004) { /* MULTIBOOT_HEADER_HAS_VBE */
         fprintf(stderr, "qemu: multiboot knows VBE. we don't.\n");
@@ -566,8 +636,8 @@  static int load_multiboot(void *fw_cfg,
         mh_load_addr = mh_entry_addr = elf_entry;
         mb_kernel_size = kernel_size;
 
-        mb_kernel_data = qemu_malloc(mb_kernel_size);
-        if (rom_copy(mb_kernel_data, elf_entry, kernel_size) != kernel_size) {
+        mbs.mb_buf = qemu_malloc(mb_kernel_size);
+        if (rom_copy(mbs.mb_buf, elf_entry, kernel_size) != kernel_size) {
             fprintf(stderr, "Error while fetching elf kernel from rom\n");
             exit(1);
         }
@@ -604,104 +674,104 @@  static int load_multiboot(void *fw_cfg,
                 mb_kernel_size, mh_load_addr);
 #endif
 
-        mb_kernel_data = qemu_malloc(mb_kernel_size);
+        mbs.mb_buf = qemu_malloc(mb_kernel_size);
         fseek(f, mb_kernel_text_offset, SEEK_SET);
-        fread(mb_kernel_data, 1, mb_kernel_size, f);
+        fread(mbs.mb_buf, 1, mb_kernel_size, f);
         fclose(f);
     }
 
-    /* blob size is only the kernel for now */
-    mb_mod_end = mh_load_addr + mb_kernel_size;
+    mbs.mb_buf_phys = mh_load_addr;
+
+    mbs.mb_buf_size = TARGET_PAGE_ALIGN(mb_kernel_size);
+    mbs.offset_mbinfo = mbs.mb_buf_size;
+
+    /* Calculate space for cmdlines and mb_mods */
+    mbs.mb_buf_size += strlen(kernel_filename) + 1;
+    mbs.mb_buf_size += strlen(kernel_cmdline) + 1;
+    if (initrd_filename) {
+        const char *r = initrd_filename;
+        mbs.mb_buf_size += strlen(r) + 1;
+        mbs.mb_mods_avail = 1;
+        while ((r = strchr(r, ','))) {
+           mbs.mb_mods_avail++;
+           r++;
+        }
+        mbs.mb_buf_size += MB_MOD_SIZE * mbs.mb_mods_avail;
+    }
+
+    mbs.mb_buf_size = TARGET_PAGE_ALIGN(mbs.mb_buf_size);
+
+    // enlarge mb_buf to hold cmdlines and mb-info structs
+    mbs.mb_buf          = qemu_realloc(mbs.mb_buf, mbs.mb_buf_size);
+    mbs.offset_cmdlines = mbs.offset_mbinfo + mbs.mb_mods_avail * MB_MOD_SIZE;
 
-    /* load modules */
-    stl_p(bootinfo + 20, 0x0); /* mods_count */
     if (initrd_filename) {
-        uint32_t mb_mod_info = 0x100;
-        uint32_t mb_mod_cmdline = 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;
+
+	mbs.offset_mods = mbs.mb_buf_size;
 
         do {
-            if (mb_mod_info + 16 > mb_mod_cmdline) {
-                printf("WARNING: Too many modules loaded, aborting.\n");
-                break;
-            }
+            char *next_space;
+            uint32_t mb_mod_length;
+	    uint32_t offs = mbs.mb_buf_size;
             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 */
-            pstrcpy((char*)bootinfo + mb_mod_cmdline,
-                    sizeof(bootinfo) - mb_mod_cmdline,
-                    initrd_filename);
-            stl_p(bootinfo + mb_mod_info + 8, mb_bootinfo + mb_mod_cmdline); /* string */
-            mb_mod_cmdline += strlen(initrd_filename) + 1;
-            if (mb_mod_cmdline > sizeof(bootinfo)) {
-                mb_mod_cmdline = sizeof(bootinfo);
-                printf("WARNING: Too many module cmdlines loaded, aborting.\n");
-                break;
-            }
+            uint32_t c = mb_add_cmdline(&mbs, initrd_filename);
             if ((next_space = strchr(initrd_filename, ' ')))
                 *next_space = '\0';
 #ifdef DEBUG_MULTIBOOT
             printf("multiboot loading module: %s\n", initrd_filename);
 #endif
-            mb_mod_start = (mb_mod_start + mb_mod_length + (TARGET_PAGE_SIZE - 1))
-                         & (TARGET_PAGE_MASK);
             mb_mod_length = get_image_size(initrd_filename);
             if (mb_mod_length < 0) {
                 fprintf(stderr, "failed to get %s image size\n", initrd_filename);
                 exit(1);
             }
-            mb_mod_end = mb_mod_start + mb_mod_length;
-            mb_mod_count++;
-
-            /* append module data at the end of last module */
-            mb_kernel_data = qemu_realloc(mb_kernel_data,
-                                          mb_mod_end - mh_load_addr);
-            load_image(initrd_filename,
-                       mb_kernel_data + mb_mod_start - mh_load_addr);
-
-            stl_p(bootinfo + mb_mod_info + 0, mb_mod_start);
-            stl_p(bootinfo + mb_mod_info + 4, mb_mod_start + mb_mod_length);
-            stl_p(bootinfo + mb_mod_info + 12, 0x0); /* reserved */
+
+	    mbs.mb_buf_size = TARGET_PAGE_ALIGN(mb_mod_length + mbs.mb_buf_size);
+	    mbs.mb_buf = qemu_realloc(mbs.mb_buf, mbs.mb_buf_size);
+
+            load_image(initrd_filename, (unsigned char *)mbs.mb_buf + offs);
+            mb_add_mod(&mbs, mbs.mb_buf_phys + offs,
+                       mbs.mb_buf_phys + offs + mb_mod_length, c);
+
 #ifdef DEBUG_MULTIBOOT
-            printf("mod_start: %#x\nmod_end:   %#x\n", mb_mod_start,
-                   mb_mod_start + mb_mod_length);
+            printf("mod_start: %p\nmod_end:   %p\n  cmdline: %#x\n",
+                   (char *)mbs.mb_buf + offs,
+                   (char *)mbs.mb_buf + offs + mb_mod_length, c);
 #endif
             initrd_filename = next_initrd+1;
-            mb_mod_info += 16;
         } while (next_initrd);
-        stl_p(bootinfo + 20, mb_mod_count); /* mods_count */
-        stl_p(bootinfo + 24, mb_bootinfo + 0x100); /* mods_addr */
     }
 
     /* Commandline support */
-    stl_p(bootinfo + 16, mb_bootinfo + cmdline);
-    snprintf((char*)bootinfo + cmdline, 0x100, "%s %s",
+    char kcmdline[strlen(kernel_filename) + strlen(kernel_cmdline) + 2];
+    snprintf(kcmdline, sizeof(kcmdline), "%s %s",
              kernel_filename, kernel_cmdline);
+    stl_p(bootinfo + MBI_CMDLINE, mb_add_cmdline(&mbs, kcmdline));
+
+    stl_p(bootinfo + MBI_MODS_ADDR,  mbs.mb_buf_phys + mbs.offset_mbinfo);
+    stl_p(bootinfo + MBI_MODS_COUNT, mbs.mb_mods_count); /* mods_count */
 
     /* 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_p(bootinfo, MULTIBOOT_FLAGS_MEMORY
-                  | MULTIBOOT_FLAGS_BOOT_DEVICE
-                  | MULTIBOOT_FLAGS_CMDLINE
-                  | MULTIBOOT_FLAGS_MODULES
-                  | MULTIBOOT_FLAGS_MMAP);
-    stl_p(bootinfo + 4, 640); /* mem_lower */
-    stl_p(bootinfo + 8, ram_size / 1024); /* mem_upper */
-    stl_p(bootinfo + 12, 0x8001ffff); /* XXX: use the -boot switch? */
-    stl_p(bootinfo + 48, mmap_addr); /* mmap_addr */
+    stl_p(bootinfo + MBI_FLAGS, MULTIBOOT_FLAGS_MEMORY
+                                | MULTIBOOT_FLAGS_BOOT_DEVICE
+                                | MULTIBOOT_FLAGS_CMDLINE
+                                | MULTIBOOT_FLAGS_MODULES
+                                | MULTIBOOT_FLAGS_MMAP);
+    stl_p(bootinfo + MBI_MEM_LOWER,   640);
+    stl_p(bootinfo + MBI_MEM_UPPER,   ram_size / 1024);
+    stl_p(bootinfo + MBI_BOOT_DEVICE, 0x8001ffff); /* XXX: use the -boot switch? */
+    stl_p(bootinfo + MBI_MMAP_ADDR,   ADDR_E820_MAP);
 
 #ifdef DEBUG_MULTIBOOT
     fprintf(stderr, "multiboot: mh_entry_addr = %#x\n", mh_entry_addr);
+    fprintf(stderr, "           mb_buf_phys   = %x\n", mbs.mb_buf_phys);
+    fprintf(stderr, "           mod_start     = %x\n", mbs.mb_buf_phys + mbs.offset_mods);
+    fprintf(stderr, "           mb_mods_count = %d\n", mbs.mb_mods_count);
 #endif
 
     /* save bootinfo off the stack */
@@ -711,11 +781,11 @@  static int load_multiboot(void *fw_cfg,
     /* Pass variables to option rom */
     fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ENTRY, mh_entry_addr);
     fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ADDR, mh_load_addr);
-    fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_SIZE, mb_mod_end - mh_load_addr);
-    fw_cfg_add_bytes(fw_cfg, FW_CFG_KERNEL_DATA, mb_kernel_data,
-                     mb_mod_end - mh_load_addr);
+    fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_SIZE, mbs.mb_buf_size);
+    fw_cfg_add_bytes(fw_cfg, FW_CFG_KERNEL_DATA,
+	             mbs.mb_buf, mbs.mb_buf_size);
 
-    fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_ADDR, mb_bootinfo);
+    fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_ADDR, ADDR_MBI);
     fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_SIZE, sizeof(bootinfo));
     fw_cfg_add_bytes(fw_cfg, FW_CFG_INITRD_DATA, mb_bootinfo_data,
                      sizeof(bootinfo));