[Qemu-devel] [PATCH] Add bootloader name to multiboot implementation

[Drew DeVault]

The name is set to "qemu".

Signed-off-by: Drew DeVault <address@hidden>
---
For the future, it may be useful to add a command line flag for setting this to
some user-specified value. I also considered naming it "qemu-system-i386" or
"qemu-system-x86_64" (as appropriate), but couldn't find an easy way to get
those strings and decided it didn't matter.

 hw/i386/multiboot.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/hw/i386/multiboot.c b/hw/i386/multiboot.c
index 985ca1e..f86d351 100644
--- a/hw/i386/multiboot.c
+++ b/hw/i386/multiboot.c
@@ -54,6 +54,7 @@ enum {
     MBI_MODS_COUNT  = 20,
     MBI_MODS_ADDR   = 24,
     MBI_MMAP_ADDR   = 48,
+    MBI_BOOTLOADER  = 64,
 
     MBI_SIZE        = 88,
 
@@ -74,6 +75,7 @@ enum {
     MULTIBOOT_FLAGS_CMDLINE     = 1 << 2,
     MULTIBOOT_FLAGS_MODULES     = 1 << 3,
     MULTIBOOT_FLAGS_MMAP        = 1 << 6,
+    MULTIBOOT_FLAGS_BOOTLOADER  = 1 << 9,
 };
 
 typedef struct {
@@ -87,6 +89,8 @@ typedef struct {
     hwaddr offset_mbinfo;
     /* offset in buffer for cmdlines in bytes */
     hwaddr offset_cmdlines;
+    /* offset in buffer for bootloader name in bytes */
+    hwaddr offset_bootloader;
     /* offset of modules in bytes */
     hwaddr offset_mods;
     /* available slots for mb modules infos */
@@ -95,6 +99,8 @@ typedef struct {
     int mb_mods_count;
 } MultibootState;
 
+const char *bootloader_name = "qemu";
+
 static uint32_t mb_add_cmdline(MultibootState *s, const char *cmdline)
 {
     hwaddr p = s->offset_cmdlines;
@@ -105,6 +111,16 @@ static uint32_t mb_add_cmdline(MultibootState *s, const 
char *cmdline)
     return s->mb_buf_phys + p;
 }
 
+static uint32_t mb_add_bootloader(MultibootState *s, const char *bootloader)
+{
+    hwaddr p = s->offset_bootloader;
+    char *b = (char *)s->mb_buf + p;
+
+    memcpy(b, bootloader, strlen(bootloader) + 1);
+    s->offset_bootloader += strlen(b) + 1;
+    return s->mb_buf_phys + p;
+}
+
 static void mb_add_mod(MultibootState *s,
                        hwaddr start, hwaddr end,
                        hwaddr cmdline_phys)
@@ -241,9 +257,10 @@ int load_multiboot(FWCfgState *fw_cfg,
     mbs.mb_buf_size = TARGET_PAGE_ALIGN(mb_kernel_size);
     mbs.offset_mbinfo = mbs.mb_buf_size;
 
-    /* Calculate space for cmdlines and mb_mods */
+    /* Calculate space for cmdlines, bootloader name, and mb_mods */
     mbs.mb_buf_size += strlen(kernel_filename) + 1;
     mbs.mb_buf_size += strlen(kernel_cmdline) + 1;
+    mbs.mb_buf_size += strlen(bootloader_name) + 1;
     if (initrd_filename) {
         const char *r = initrd_filename;
         mbs.mb_buf_size += strlen(r) + 1;
@@ -257,9 +274,11 @@ int load_multiboot(FWCfgState *fw_cfg,
 
     mbs.mb_buf_size = TARGET_PAGE_ALIGN(mbs.mb_buf_size);
 
-    /* enlarge mb_buf to hold cmdlines and mb-info structs */
-    mbs.mb_buf          = g_realloc(mbs.mb_buf, mbs.mb_buf_size);
-    mbs.offset_cmdlines = mbs.offset_mbinfo + mbs.mb_mods_avail * MB_MOD_SIZE;
+    /* enlarge mb_buf to hold cmdlines, bootloader, mb-info structs */
+    mbs.mb_buf            = g_realloc(mbs.mb_buf, mbs.mb_buf_size);
+    mbs.offset_cmdlines   = mbs.offset_mbinfo + mbs.mb_mods_avail * 
MB_MOD_SIZE;
+    mbs.offset_bootloader = mbs.offset_cmdlines + strlen(kernel_filename) + 1 
+                            + strlen(kernel_cmdline) + 1;
 
     if (initrd_filename) {
         char *next_initrd, not_last;
@@ -306,6 +325,8 @@ int load_multiboot(FWCfgState *fw_cfg,
              kernel_filename, kernel_cmdline);
     stl_p(bootinfo + MBI_CMDLINE, mb_add_cmdline(&mbs, kcmdline));
 
+    stl_p(bootinfo + MBI_BOOTLOADER, mb_add_bootloader(&mbs, bootloader_name));
+
     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 */
 
@@ -314,7 +335,8 @@ int load_multiboot(FWCfgState *fw_cfg,
                                 | MULTIBOOT_FLAGS_BOOT_DEVICE
                                 | MULTIBOOT_FLAGS_CMDLINE
                                 | MULTIBOOT_FLAGS_MODULES
-                                | MULTIBOOT_FLAGS_MMAP);
+                                | MULTIBOOT_FLAGS_MMAP
+                                | MULTIBOOT_FLAGS_BOOTLOADER);
     stl_p(bootinfo + MBI_BOOT_DEVICE, 0x8000ffff); /* XXX: use the -boot 
switch? */
     stl_p(bootinfo + MBI_MMAP_ADDR,   ADDR_E820_MAP);
 
-- 
2.1.2