Use "struct boot_params" in example launcher

Now that the "struct boot_params" is userspace accessible, we don't need
magic numbers.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 22 insertions, 25 deletions

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 3949620e42fa..5bdc37f81842 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -52,7 +52,7 @@ typedef uint8_t u8;
 #include "linux/virtio_blk.h"
 #include "linux/virtio_console.h"
 #include "linux/virtio_ring.h"
-#include "asm-x86/e820.h"
+#include "asm-x86/bootparam.h"
 /*:*/
 
 #define PAGE_PRESENT 0x7        /* Present, RW, Execute */
@@ -335,7 +335,7 @@ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr)
  * the funky header so we know where in the file to load, and away we go! */
 static unsigned long load_bzimage(int fd)
 {
-        u8 hdr[1024];
+        struct boot_params boot;
         int r;
         /* Modern bzImages get loaded at 1M. */
         void *p = from_guest_phys(0x100000);
@@ -343,22 +343,21 @@ static unsigned long load_bzimage(int fd)
         /* Go back to the start of the file and read the header.  It should be
          * a Linux boot header (see Documentation/i386/boot.txt) */
         lseek(fd, 0, SEEK_SET);
-        read(fd, hdr, sizeof(hdr));
+        read(fd, &boot, sizeof(boot));
 
-        /* At offset 0x202, we expect the magic "HdrS" */
-        if (memcmp(hdr + 0x202, "HdrS", 4) != 0)
+        /* Inside the setup_hdr, we expect the magic "HdrS" */
+        if (memcmp(&boot.hdr.header, "HdrS", 4) != 0)
                 errx(1, "This doesn't look like a bzImage to me");
 
-        /* The byte at 0x1F1 tells us how many extra sectors of
-         * header: skip over them all. */
-        lseek(fd, (unsigned long)(hdr[0x1F1]+1) * 512, SEEK_SET);
+        /* Skip over the extra sectors of the header. */
+        lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET);
 
         /* Now read everything into memory. in nice big chunks. */
         while ((r = read(fd, p, 65536)) > 0)
                 p += r;
 
-        /* Finally, 0x214 tells us where to start the kernel. */
-        return *(unsigned long *)&hdr[0x214];
+        /* Finally, code32_start tells us where to enter the kernel. */
+        return boot.hdr.code32_start;
 }
 
 /*L:140 Loading the kernel is easy when it's a "vmlinux", but most kernels
@@ -1531,7 +1530,7 @@ int main(int argc, char *argv[])
         /* A temporary and the /dev/lguest file descriptor. */
         int i, c, lguest_fd;
         /* The boot information for the Guest. */
-        void *boot;
+        struct boot_params *boot;
         /* If they specify an initrd file to load. */
         const char *initrd_name = NULL;
 
@@ -1607,10 +1606,10 @@ int main(int argc, char *argv[])
                 initrd_size = load_initrd(initrd_name, mem);
                 /* These are the location in the Linux boot header where the
                  * start and size of the initrd are expected to be found. */
-                *(unsigned long *)(boot+0x218) = mem - initrd_size;
-                *(unsigned long *)(boot+0x21c) = initrd_size;
+                boot->hdr.ramdisk_image = mem - initrd_size;
+                boot->hdr.ramdisk_size = initrd_size;
                 /* The bootloader type 0xFF means "unknown"; that's OK. */
-                *(unsigned char *)(boot+0x210) = 0xFF;
+                boot->hdr.type_of_loader = 0xFF;
         }
 
         /* Set up the initial linear pagetables, starting below the initrd. */
@@ -1618,23 +1617,21 @@ int main(int argc, char *argv[])
 
         /* The Linux boot header contains an "E820" memory map: ours is a
          * simple, single region. */
-        *(char*)(boot+E820NR) = 1;
-        *((struct e820entry *)(boot+E820MAP))
-                = ((struct e820entry) { 0, mem, E820_RAM });
+        boot->e820_entries = 1;
+        boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM });
         /* The boot header contains a command line pointer: we put the command
-         * line after the boot header (at address 4096) */
-        *(u32 *)(boot + 0x228) = 4096;
-        concat(boot + 4096, argv+optind+2);
+         * line after the boot header. */
+        boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1);
+        concat((char *)(boot + 1), argv+optind+2);
 
         /* Boot protocol version: 2.07 supports the fields for lguest. */
-        *(u16 *)(boot + 0x206) = 0x207;
+        boot->hdr.version = 0x207;
 
         /* The hardware_subarch value of "1" tells the Guest it's an lguest. */
-        *(u32 *)(boot + 0x23c) = 1;
+        boot->hdr.hardware_subarch = 1;
 
-        /* Set bit 6 of the loadflags (aka. KEEP_SEGMENTS) so the entry path
-         * does not try to reload segment registers. */
-        *(u8 *)(boot + 0x211) |= (1 << 6);
+        /* Tell the entry path not to try to reload segment registers. */
+        boot->hdr.loadflags |= KEEP_SEGMENTS;
 
         /* We tell the kernel to initialize the Guest: this returns the open
          * /dev/lguest file descriptor. */