Use an option rom instead of boot sector for -kernel
Generate an option rom instead of using a hijacked boot sector for kernel
booting. This just requires adding a small option ROM header and a few more
instructions to the boot sector to take over the int19 vector and run our
boot code.
A disk is no longer needed when using -kernel on x86.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5650 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/hw/pc.c b/hw/pc.c
index 167d628..1486b68 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -438,30 +438,45 @@
/* Generate an initial boot sector which sets state and jump to
a specified vector */
-static void generate_bootsect(uint32_t gpr[8], uint16_t segs[6], uint16_t ip)
+static void generate_bootsect(uint8_t *option_rom,
+ uint32_t gpr[8], uint16_t segs[6], uint16_t ip)
{
- uint8_t bootsect[512], *p;
+ uint8_t rom[512], *p, *reloc;
+ uint8_t sum;
int i;
- int hda;
- hda = drive_get_index(IF_IDE, 0, 0);
- if (hda == -1) {
- fprintf(stderr, "A disk image must be given for 'hda' when booting "
- "a Linux kernel\n(if you really don't want it, use /dev/zero)\n");
- exit(1);
- }
+ memset(rom, 0, sizeof(rom));
- memset(bootsect, 0, sizeof(bootsect));
+ p = rom;
+ /* Make sure we have an option rom signature */
+ *p++ = 0x55;
+ *p++ = 0xaa;
- /* Copy the MSDOS partition table if possible */
- bdrv_read(drives_table[hda].bdrv, 0, bootsect, 1);
+ /* ROM size in sectors*/
+ *p++ = 1;
- /* Make sure we have a partition signature */
- bootsect[510] = 0x55;
- bootsect[511] = 0xaa;
+ /* Hook int19 */
+ *p++ = 0x50; /* push ax */
+ *p++ = 0x1e; /* push ds */
+ *p++ = 0x31; *p++ = 0xc0; /* xor ax, ax */
+ *p++ = 0x8e; *p++ = 0xd8; /* mov ax, ds */
+
+ *p++ = 0xc7; *p++ = 0x06; /* movvw _start,0x64 */
+ *p++ = 0x64; *p++ = 0x00;
+ reloc = p;
+ *p++ = 0x00; *p++ = 0x00;
+
+ *p++ = 0x8c; *p++ = 0x0e; /* mov cs,0x66 */
+ *p++ = 0x66; *p++ = 0x00;
+
+ *p++ = 0x1f; /* pop ds */
+ *p++ = 0x58; /* pop ax */
+ *p++ = 0xcb; /* lret */
+
/* Actual code */
- p = bootsect;
+ *reloc = (p - rom);
+
*p++ = 0xfa; /* CLI */
*p++ = 0xfc; /* CLD */
@@ -491,7 +506,13 @@
*p++ = segs[1]; /* CS */
*p++ = segs[1] >> 8;
- bdrv_set_boot_sector(drives_table[hda].bdrv, bootsect, sizeof(bootsect));
+ /* sign rom */
+ sum = 0;
+ for (i = 0; i < (sizeof(rom) - 1); i++)
+ sum += rom[i];
+ rom[sizeof(rom) - 1] = -sum;
+
+ memcpy(option_rom, rom, sizeof(rom));
}
static long get_file_size(FILE *f)
@@ -508,7 +529,8 @@
return size;
}
-static void load_linux(const char *kernel_filename,
+static void load_linux(uint8_t *option_rom,
+ const char *kernel_filename,
const char *initrd_filename,
const char *kernel_cmdline)
{
@@ -658,7 +680,7 @@
memset(gpr, 0, sizeof gpr);
gpr[4] = cmdline_addr-real_addr-16; /* SP (-16 is paranoia) */
- generate_bootsect(gpr, seg, 0);
+ generate_bootsect(option_rom, gpr, seg, 0);
}
static void main_cpu_reset(void *opaque)
@@ -862,6 +884,15 @@
int size, offset;
offset = 0;
+ if (linux_boot) {
+ option_rom_offset = qemu_ram_alloc(TARGET_PAGE_SIZE);
+ load_linux(phys_ram_base + option_rom_offset,
+ kernel_filename, initrd_filename, kernel_cmdline);
+ cpu_register_physical_memory(0xd0000, TARGET_PAGE_SIZE,
+ option_rom_offset | IO_MEM_ROM);
+ offset = TARGET_PAGE_SIZE;
+ }
+
for (i = 0; i < nb_option_roms; i++) {
size = get_image_size(option_rom[i]);
if (size < 0) {
@@ -891,9 +922,6 @@
bochs_bios_init();
- if (linux_boot)
- load_linux(kernel_filename, initrd_filename, kernel_cmdline);
-
cpu_irq = qemu_allocate_irqs(pic_irq_request, NULL, 1);
i8259 = i8259_init(cpu_irq[0]);
ferr_irq = i8259[13];
