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Convert multiboot to fw_cfg backed data storage

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Right now we load the guest kernel to RAM, fire off the BIOS, hope it
doesn't clobber memory and run an option rom that jumps into the kernel.

That breaks with SeaBIOS, as that clears memory. So let's read all
kernel, module etc. data using the fw_cfg interface when in the int19
handler.

This patch implements said mechanism for multiboot.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Alexander Graf 2009-11-12 21:53:12 +01:00 • committed by Anthony Liguori
parent 235f86ef01
commit 77873196f3
3 changed files with 95 additions and 32 deletions
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45
hw/pc.c
View file

@ -603,6 +603,8 @@ static int load_multiboot(void *fw_cfg,
uint32_t mb_mod_end;
uint8_t bootinfo[0x500];
uint32_t cmdline = 0x200;
uint8_t *mb_kernel_data;
uint8_t *mb_bootinfo_data;
/* Ok, let's see if it is a multiboot image.
The header is 12x32bit long, so the latest entry may be 8192 - 48. */
@ -643,6 +645,12 @@ 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) {
fprintf(stderr, "Error while fetching elf kernel from rom\n");
exit(1);
}
#ifdef DEBUG_MULTIBOOT
fprintf(stderr, "qemu: loading multiboot-elf kernel (%#x bytes) with entry %#zx\n",
mb_kernel_size, (size_t)mh_entry_addr);
@ -656,7 +664,6 @@ static int load_multiboot(void *fw_cfg,
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);
uint8_t *kernel;
mh_entry_addr = ldl_p(header+i+28);
mb_kernel_size = get_file_size(f) - mb_kernel_text_offset;
@ -676,12 +683,9 @@ static int load_multiboot(void *fw_cfg,
mb_kernel_size, mh_load_addr);
#endif
kernel = qemu_malloc(mb_kernel_size);
mb_kernel_data = qemu_malloc(mb_kernel_size);
fseek(f, mb_kernel_text_offset, SEEK_SET);
fread(kernel, 1, mb_kernel_size, f);
rom_add_blob_fixed(kernel_filename, kernel, mb_kernel_size,
mh_load_addr);
qemu_free(kernel);
fread(mb_kernel_data, 1, mb_kernel_size, f);
fclose(f);
}
@ -732,9 +736,14 @@ static int load_multiboot(void *fw_cfg,
exit(1);
}
mb_mod_end = mb_mod_start + mb_mod_length;
rom_add_file_fixed(initrd_filename, mb_mod_start);
mb_mod_count++;
/* append module data at the end of last module */
mb_kernel_data = qemu_realloc(mb_kernel_data,
mh_load_addr - mb_mod_end);
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 */
@ -774,13 +783,21 @@ static int load_multiboot(void *fw_cfg,
fprintf(stderr, "multiboot: mh_entry_addr = %#x\n", mh_entry_addr);
#endif
/* Pass variables to option rom */
fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ADDR, mh_entry_addr);
fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_ADDR, mb_bootinfo);
fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_SIZE, mmap_addr);
/* save bootinfo off the stack */
mb_bootinfo_data = qemu_malloc(sizeof(bootinfo));
memcpy(mb_bootinfo_data, bootinfo, sizeof(bootinfo));
rom_add_blob_fixed("multiboot-info", bootinfo, sizeof(bootinfo),
mb_bootinfo);
/* 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_INITRD_ADDR, mb_bootinfo);
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));
option_rom[nb_option_roms] = "multiboot.bin";
nb_option_roms++;