Re: question about adding a field into linux boot header

[GuoMinskey]

thank you for response.

Sorry for the confusion.  It was my fault. I just use qemu to debug my change.

It is a kernel panic.  It panic so early, so that I made a mistake and considered

it as a panic in grub. 

I am using grub repo (revno: 3116). Now, I can see the kernel panic message:

 "PANIC: early exception 08 rip 246:10 error ffffff8102b785 cr2 ffffffffff47900b"

The panic message comes from linux kernel: early_idt_handlers in the file

arch/x86/kernel/head_64.S.

So, it doesn't matter with grub.

 /* For the Linux/i386 boot protocol version 2.03.  */

 struct linux_kernel_header

 {

@@ -130,6 +146,8 @@

   grub_uint16_t pad1;                  /* Unused */

   grub_uint32_t cmd_line_ptr;          /* Points to the kernel command line */

   grub_uint32_t initrd_addr_max;        /* Highest address for initrd */

+  grub_uint32_t pad2[8];

+  grub_uint64_t setup_data;

 } __attribute__ ((packed));

And then,  I tried to use setup_data field to pass an pointer (which points to a binary

blob) to Linux kernel, 

=== modified file 'grub-core/loader/i386/linux.c'

--- grub-core/loader/i386/linux.c       2011-03-09 17:38:31 +0000

+++ grub-core/loader/i386/linux.c       2011-03-28 15:44:34 +0000

@@ -994,7 +994,89 @@

   return grub_errno;

 }

-static grub_command_t cmd_linux, cmd_initrd;

+static grub_err_t

+grub_cmd_ucode (grub_command_t cmd __attribute__ ((unused)),

+                int argc, char *argv[])

+{

+  grub_file_t file = 0;

+  grub_ssize_t size;

+  grub_addr_t addr_min, addr_max;

+  grub_err_t err;

+  struct linux_kernel_header *lh;

+  grub_relocator_chunk_t ch;

+  void *ucode_mem;

+  grub_addr_t ucode_mem_target;

+  struct setup_data *hdr;

+

+  if (argc == 0)

+    {

+      grub_error (GRUB_ERR_BAD_ARGUMENT, "no module specified");

+      goto fail;

+    }

+

+  if (! loaded)

+    {

+      grub_error (GRUB_ERR_BAD_ARGUMENT, "you need to load the kernel first");

+      goto fail;

+    }

+

+  grub_file_filter_disable_compression ();

+  file = grub_file_open (argv[0]);

+  size = grub_file_size(file);

+

+  lh = (struct linux_kernel_header *) real_mode_mem;

+  if (grub_le_to_cpu16(lh->version) < 0x0209)

+    {

+      grub_printf("%s:%d: header version=0x%x(<0x0209)\n",

+           __FUNCTION__, __LINE__, lh->version);

+      goto fail;

+    }

+

+  addr_max = grub_cpu_to_le32(lh->initrd_addr_max);

+  if (addr_max > GRUB_LINUX_INITRD_MAX_ADDRESS)

+      addr_max = GRUB_LINUX_INITRD_MAX_ADDRESS;

+  addr_max -= 0x10000;

+

+  if ((linux_mem_size != 0) && (linux_mem_size < addr_max))

+       addr_max = linux_mem_size;

+  addr_max = (addr_max - size - sizeof(*hdr)) & ~0xFFF;

+  addr_min = prot_mode_target;

+

+  grub_printf("microcode addr_min=%p, add_max=%p\n", 

+       (void*)addr_min, (void *)addr_max);

+

+  err = grub_relocator_alloc_chunk_align(relocator, &ch, addr_min,

+                                       addr_max, size + sizeof(*hdr),

+                                       0x1000, GRUB_RELOCATOR_PREFERENCE_HIGH);

+  if (err) return err;

+  ucode_mem = get_virtual_current_address(ch);

+  ucode_mem_target = get_physical_target_address(ch);

+

+  if (grub_file_read(file, (unsigned char*)ucode_mem + sizeof(*hdr), size) != size)

+     {

+       grub_error (GRUB_ERR_FILE_READ_ERROR, "couldn't read file");

+       goto fail;

+     }

+

+  hdr = (struct setup_data *)ucode_mem;

+  hdr->type = SETUP_MICROCODE;

+  hdr->len = size;

+  hdr->next = 0;

+

+  lh->setup_data = ucode_mem_target;

+

+  grub_printf("%s: header_version=0x%x, ucode_size=%d\n", __FUNCTION__,

+      grub_le_to_cpu16 (lh->version), size);

+      

+

+ fail:

+  if (file)

+    grub_file_close (file);

+

+  return grub_errno;

+}

+

+static grub_command_t cmd_linux, cmd_initrd, cmd_ucode;

thanks,

-minskey

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