grub 2 module for appending extra args

/* append.c - append extra command line args to linux kernel */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2003,2007  Free Software Foundation, Inc.
 *  Copyright (C) 2003  NIIBE Yutaka <gniibe@m17n.org>
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <grub/extcmd.h>

#include <grub/loader.h>
#include <grub/memory.h>
#include <grub/normal.h>
#include <grub/file.h>
#include <grub/disk.h>
#include <grub/err.h>
#include <grub/misc.h>
#include <grub/types.h>
#include <grub/dl.h>
#include <grub/mm.h>
#include <grub/term.h>
#include <grub/cpu/linux.h>
#include <grub/video.h>
#include <grub/video_fb.h>
#include <grub/command.h>
#include <grub/i386/relocator.h>
#include <grub/i18n.h>
#include <grub/lib/cmdline.h>
#include <grub/linux.h>

GRUB_MOD_LICENSE ("GPLv3+");

#ifdef GRUB_MACHINE_PCBIOS
#include <grub/i386/pc/vesa_modes_table.h>
#endif

#ifdef GRUB_MACHINE_EFI
#include <grub/efi/efi.h>
#define HAS_VGA_TEXT 0
#define DEFAULT_VIDEO_MODE "auto"
#define ACCEPTS_PURE_TEXT 0
#elif defined (GRUB_MACHINE_IEEE1275)
#include <grub/ieee1275/ieee1275.h>
#define HAS_VGA_TEXT 0
#define DEFAULT_VIDEO_MODE "text"
#define ACCEPTS_PURE_TEXT 1
#else
#include <grub/i386/pc/vbe.h>
#include <grub/i386/pc/console.h>
#define HAS_VGA_TEXT 1
#define DEFAULT_VIDEO_MODE "text"
#define ACCEPTS_PURE_TEXT 1
#endif

static grub_dl_t my_mod;

static grub_size_t linux_mem_size;
static int loaded;
static void *prot_mode_mem;
static grub_addr_t prot_mode_target;
static void *initrd_mem;
static grub_addr_t initrd_mem_target;
static grub_size_t prot_init_space;
static struct grub_relocator *relocator = NULL;
static void *efi_mmap_buf;
static grub_size_t maximal_cmdline_size;
static struct linux_kernel_params linux_params;
static char *linux_cmdline;
#ifdef GRUB_MACHINE_EFI
static grub_efi_uintn_t efi_mmap_size;
#else
static const grub_size_t efi_mmap_size = 0;
#endif

// To remember what we should append
static int appended_args_count = 0;
static char **appended_args = NULL;

// Clean all remembered args
static void clean_args(void)
{
  int i;
  if(appended_args_count == 0)
    return;
  if(!appended_args)
  {
    appended_args_count = 0;
    return;
  }

  for(i = 0; i < appended_args_count; ++i)
    grub_free(appended_args[i]);
  grub_free(appended_args);
  appended_args_count = 0;
}

static grub_err_t grub_cmd_append(grub_extcmd_context_t ctxt __attribute__((unused)),
    int argc, char **args)
{
  int i;

  if(argc < 1) // Print what we have now!
  {
    if(appended_args_count == 0 || !appended_args)
      grub_printf("%s\n", "No arguments to append to kernel command line...");
    else
    {
      grub_printf("%s:\n", "Arguments to append to kernel command line");
      for(i = 0; i < appended_args_count; ++i)
        grub_printf(" %s\n", appended_args[i] );
    }
  }
  else // Set new arguments to append
  {
    clean_args(); // Clean old args
    appended_args = grub_malloc(argc * sizeof(char*) );
    if(!appended_args) // No Mem??
    {
      grub_printf("%s\n", "No memeory to copy args??");
      return 0;
    }
    for(i = 0; i < argc; ++i)
    {
      appended_args[i] = grub_strdup(args[i] );
      if(!appended_args[i] )
      {
        grub_printf("%s (%d)\n", "No memeory to copy all args", i);
        break;
      }
    }
    appended_args_count = i; // Can be less than argc if no mem(
  }

// After that we can write something like this:
//    grub_create_loader_cmdline (appended_args_count, appended_args, cmdline + offset, size - offset);
// but how to find offset???

  return 0;
}


/// FROM loader/i386/linux.c
static inline grub_size_t
page_align (grub_size_t size)
{
  return (size + (1 << 12) - 1) & (~((1 << 12) - 1));
}

#ifdef GRUB_MACHINE_EFI
/* Find the optimal number of pages for the memory map. Is it better to
   move this code to efi/mm.c?  */
static grub_efi_uintn_t
find_efi_mmap_size (void)
{
  static grub_efi_uintn_t mmap_size = 0;

  if (mmap_size != 0)
    return mmap_size;

  mmap_size = (1 << 12);
  while (1)
    {
      int ret;
      grub_efi_memory_descriptor_t *mmap;
      grub_efi_uintn_t desc_size;
      grub_efi_uintn_t cur_mmap_size = mmap_size;

      mmap = grub_malloc (cur_mmap_size);
      if (! mmap)
    return 0;

      ret = grub_efi_get_memory_map (&cur_mmap_size, mmap, 0, &desc_size, 0);
      grub_free (mmap);

      if (ret < 0)
    {
      grub_error (GRUB_ERR_IO, "cannot get memory map");
      return 0;
    }
      else if (ret > 0)
    break;

      if (mmap_size < cur_mmap_size)
    mmap_size = cur_mmap_size;
      mmap_size += (1 << 12);
    }

  /* Increase the size a bit for safety, because GRUB allocates more on
     later, and EFI itself may allocate more.  */
  mmap_size += (3 << 12);

  mmap_size = page_align (mmap_size);
  return mmap_size;
}

#endif

/* Helper for find_mmap_size.  */
static int
count_hook (grub_uint64_t addr __attribute__ ((unused)),
        grub_uint64_t size __attribute__ ((unused)),
        grub_memory_type_t type __attribute__ ((unused)), void *data)
{
  grub_size_t *count = data;

  (*count)++;
  return 0;
}

/* Find the optimal number of pages for the memory map. */
static grub_size_t
find_mmap_size (void)
{
  grub_size_t count = 0, mmap_size;

  grub_mmap_iterate (count_hook, &count);

  mmap_size = count * sizeof (struct grub_e820_mmap);

  /* Increase the size a bit for safety, because GRUB allocates more on
     later.  */
  mmap_size += (1 << 12);

  return page_align (mmap_size);
}

static void
free_pages (void)
{
  grub_relocator_unload (relocator);
  relocator = NULL;
  prot_mode_mem = initrd_mem = 0;
  prot_mode_target = initrd_mem_target = 0;
}

/* Allocate pages for the real mode code and the protected mode code
   for linux as well as a memory map buffer.  */
static grub_err_t
allocate_pages (grub_size_t prot_size, grub_size_t *align,
        grub_size_t min_align, int relocatable,
        grub_uint64_t preferred_address)
{
  grub_err_t err;

  if (prot_size == 0)
    prot_size = 1;

  prot_size = page_align (prot_size);

  /* Initialize the memory pointers with NULL for convenience.  */
  free_pages ();

  relocator = grub_relocator_new ();
  if (!relocator)
    {
      err = grub_errno;
      goto fail;
    }

  /* FIXME: Should request low memory from the heap when this feature is
     implemented.  */

  {
    grub_relocator_chunk_t ch;
    if (relocatable)
      {
    err = grub_relocator_alloc_chunk_align (relocator, &ch,
                        preferred_address,
                        preferred_address,
                        prot_size, 1,
                        GRUB_RELOCATOR_PREFERENCE_LOW,
                        1);
    for (; err && *align + 1 > min_align; (*align)--)
      {
        grub_errno = GRUB_ERR_NONE;
        err = grub_relocator_alloc_chunk_align (relocator, &ch,
                            0x1000000,
                            0xffffffff & ~prot_size,
                            prot_size, 1 << *align,
                            GRUB_RELOCATOR_PREFERENCE_LOW,
                            1);
      }
    if (err)
      goto fail;
      }
    else
      err = grub_relocator_alloc_chunk_addr (relocator, &ch,
                         preferred_address,
                         prot_size);
    if (err)
      goto fail;
    prot_mode_mem = get_virtual_current_address (ch);
    prot_mode_target = get_physical_target_address (ch);
  }

  grub_dprintf ("linux", "prot_mode_mem = %p, prot_mode_target = %lx, prot_size = %x\n",
                prot_mode_mem, (unsigned long) prot_mode_target,
        (unsigned) prot_size);
  return GRUB_ERR_NONE;

 fail:
  free_pages ();
  return err;
}

static grub_err_t
grub_e820_add_region (struct grub_e820_mmap *e820_map, int *e820_num,
                      grub_uint64_t start, grub_uint64_t size,
                      grub_uint32_t type)
{
  int n = *e820_num;

  if ((n > 0) && (e820_map[n - 1].addr + e820_map[n - 1].size == start) &&
      (e820_map[n - 1].type == type))
      e820_map[n - 1].size += size;
  else
    {
      e820_map[n].addr = start;
      e820_map[n].size = size;
      e820_map[n].type = type;
      (*e820_num)++;
    }
  return GRUB_ERR_NONE;
}

static grub_err_t
grub_linux_setup_video (struct linux_kernel_params *params)
{
  struct grub_video_mode_info mode_info;
  void *framebuffer;
  grub_err_t err;
  grub_video_driver_id_t driver_id;
  const char *gfxlfbvar = grub_env_get ("gfxpayloadforcelfb");

  driver_id = grub_video_get_driver_id ();

  if (driver_id == GRUB_VIDEO_DRIVER_NONE)
    return 1;

  err = grub_video_get_info_and_fini (&mode_info, &framebuffer);

  if (err)
    {
      grub_errno = GRUB_ERR_NONE;
      return 1;
    }

  params->lfb_width = mode_info.width;
  params->lfb_height = mode_info.height;
  params->lfb_depth = mode_info.bpp;
  params->lfb_line_len = mode_info.pitch;

  params->lfb_base = (grub_size_t) framebuffer;
  params->lfb_size = ALIGN_UP (params->lfb_line_len * params->lfb_height, 65536);

  params->red_mask_size = mode_info.red_mask_size;
  params->red_field_pos = mode_info.red_field_pos;
  params->green_mask_size = mode_info.green_mask_size;
  params->green_field_pos = mode_info.green_field_pos;
  params->blue_mask_size = mode_info.blue_mask_size;
  params->blue_field_pos = mode_info.blue_field_pos;
  params->reserved_mask_size = mode_info.reserved_mask_size;
  params->reserved_field_pos = mode_info.reserved_field_pos;

  if (gfxlfbvar && (gfxlfbvar[0] == '1' || gfxlfbvar[0] == 'y'))
    params->have_vga = GRUB_VIDEO_LINUX_TYPE_SIMPLE;
  else
    {
      switch (driver_id)
    {
    case GRUB_VIDEO_DRIVER_VBE:
      params->lfb_size >>= 16;
      params->have_vga = GRUB_VIDEO_LINUX_TYPE_VESA;
      break;

    case GRUB_VIDEO_DRIVER_EFI_UGA:
    case GRUB_VIDEO_DRIVER_EFI_GOP:
      params->have_vga = GRUB_VIDEO_LINUX_TYPE_EFIFB;
      break;

      /* FIXME: check if better id is available.  */
    case GRUB_VIDEO_DRIVER_SM712:
    case GRUB_VIDEO_DRIVER_SIS315PRO:
    case GRUB_VIDEO_DRIVER_VGA:
    case GRUB_VIDEO_DRIVER_CIRRUS:
    case GRUB_VIDEO_DRIVER_BOCHS:
    case GRUB_VIDEO_DRIVER_RADEON_FULOONG2E:
    case GRUB_VIDEO_DRIVER_RADEON_YEELOONG3A:
    case GRUB_VIDEO_DRIVER_IEEE1275:
    case GRUB_VIDEO_DRIVER_COREBOOT:
      /* Make gcc happy. */
    case GRUB_VIDEO_DRIVER_XEN:
    case GRUB_VIDEO_DRIVER_SDL:
    case GRUB_VIDEO_DRIVER_NONE:
    case GRUB_VIDEO_ADAPTER_CAPTURE:
      params->have_vga = GRUB_VIDEO_LINUX_TYPE_SIMPLE;
      break;
    }
    }

#ifdef GRUB_MACHINE_PCBIOS
  /* VESA packed modes may come with zeroed mask sizes, which need
     to be set here according to DAC Palette width.  If we don't,
     this results in Linux displaying a black screen.  */
  if (driver_id == GRUB_VIDEO_DRIVER_VBE && mode_info.bpp <= 8)
    {
      struct grub_vbe_info_block controller_info;
      int status;
      int width = 8;

      status = grub_vbe_bios_get_controller_info (&controller_info);

      if (status == GRUB_VBE_STATUS_OK &&
      (controller_info.capabilities & GRUB_VBE_CAPABILITY_DACWIDTH))
    status = grub_vbe_bios_set_dac_palette_width (&width);

      if (status != GRUB_VBE_STATUS_OK)
    /* 6 is default after mode reset.  */
    width = 6;

      params->red_mask_size = params->green_mask_size
    = params->blue_mask_size = width;
      params->reserved_mask_size = 0;
    }
#endif

  return GRUB_ERR_NONE;
}

/* Context for grub_linux_boot.  */
struct grub_linux_boot_ctx
{
  grub_addr_t real_mode_target;
  grub_size_t real_size;
  struct linux_kernel_params *params;
  int e820_num;
};

/* Helper for grub_linux_boot.  */
static int
grub_linux_boot_mmap_find (grub_uint64_t addr, grub_uint64_t size,
               grub_memory_type_t type, void *data)
{
  struct grub_linux_boot_ctx *ctx = data;

  /* We must put real mode code in the traditional space.  */
  if (type != GRUB_MEMORY_AVAILABLE || addr > 0x90000)
    return 0;

  if (addr + size < 0x10000)
    return 0;

  if (addr < 0x10000)
    {
      size += addr - 0x10000;
      addr = 0x10000;
    }

  if (addr + size > 0x90000)
    size = 0x90000 - addr;

  if (ctx->real_size + efi_mmap_size > size)
    return 0;

  grub_dprintf ("linux", "addr = %lx, size = %x, need_size = %x\n",
        (unsigned long) addr,
        (unsigned) size,
        (unsigned) (ctx->real_size + efi_mmap_size));
  ctx->real_mode_target = ((addr + size) - (ctx->real_size + efi_mmap_size));
  return 1;
}

/* GRUB types conveniently match E820 types.  */
static int
grub_linux_boot_mmap_fill (grub_uint64_t addr, grub_uint64_t size,
               grub_memory_type_t type, void *data)
{
  struct grub_linux_boot_ctx *ctx = data;

  if (grub_e820_add_region (ctx->params->e820_map, &ctx->e820_num,
                addr, size, type))
    return 1;

  return 0;
}

static grub_err_t
grub_linux_boot (void)
{
  grub_err_t err = 0;
  const char *modevar;
  char *tmp;
  struct grub_relocator32_state state;
  void *real_mode_mem;
  struct grub_linux_boot_ctx ctx = {
    .real_mode_target = 0
  };
  grub_size_t mmap_size;
  grub_size_t cl_offset;

#ifdef GRUB_MACHINE_IEEE1275
  {
    const char *bootpath;
    grub_ssize_t len;

    bootpath = grub_env_get ("root");
    if (bootpath)
      grub_ieee1275_set_property (grub_ieee1275_chosen,
                  "bootpath", bootpath,
                  grub_strlen (bootpath) + 1,
                  &len);
    linux_params.ofw_signature = GRUB_LINUX_OFW_SIGNATURE;
    linux_params.ofw_num_items = 1;
    linux_params.ofw_cif_handler = (grub_uint32_t) grub_ieee1275_entry_fn;
    linux_params.ofw_idt = 0;
  }
#endif

  modevar = grub_env_get ("gfxpayload");

  /* Now all graphical modes are acceptable.
     May change in future if we have modes without framebuffer.  */
  if (modevar && *modevar != 0)
    {
      tmp = grub_xasprintf ("%s;" DEFAULT_VIDEO_MODE, modevar);
      if (! tmp)
    return grub_errno;
#if ACCEPTS_PURE_TEXT
      err = grub_video_set_mode (tmp, 0, 0);
#else
      err = grub_video_set_mode (tmp, GRUB_VIDEO_MODE_TYPE_PURE_TEXT, 0);
#endif
      grub_free (tmp);
    }
  else       /* We can't go back to text mode from coreboot fb.  */
#ifdef GRUB_MACHINE_COREBOOT
    if (grub_video_get_driver_id () == GRUB_VIDEO_DRIVER_COREBOOT)
      err = GRUB_ERR_NONE;
    else
#endif
      {
#if ACCEPTS_PURE_TEXT
    err = grub_video_set_mode (DEFAULT_VIDEO_MODE, 0, 0);
#else
    err = grub_video_set_mode (DEFAULT_VIDEO_MODE,
                 GRUB_VIDEO_MODE_TYPE_PURE_TEXT, 0);
#endif
      }

  if (err)
    {
      grub_print_error ();
      grub_puts_ (N_("Booting in blind mode"));
      grub_errno = GRUB_ERR_NONE;
    }

  if (grub_linux_setup_video (&linux_params))
    {
#if defined (GRUB_MACHINE_PCBIOS) || defined (GRUB_MACHINE_COREBOOT) || defined (GRUB_MACHINE_QEMU)
      linux_params.have_vga = GRUB_VIDEO_LINUX_TYPE_TEXT;
      linux_params.video_mode = 0x3;
#else
      linux_params.have_vga = 0;
      linux_params.video_mode = 0;
      linux_params.video_width = 0;
      linux_params.video_height = 0;
#endif
    }


#ifndef GRUB_MACHINE_IEEE1275
  if (linux_params.have_vga == GRUB_VIDEO_LINUX_TYPE_TEXT)
#endif
    {
      grub_term_output_t term;
      int found = 0;
      FOR_ACTIVE_TERM_OUTPUTS(term)
    if (grub_strcmp (term->name, "vga_text") == 0
        || grub_strcmp (term->name, "console") == 0
        || grub_strcmp (term->name, "ofconsole") == 0)
      {
        struct grub_term_coordinate pos = grub_term_getxy (term);
        linux_params.video_cursor_x = pos.x;
        linux_params.video_cursor_y = pos.y;
        linux_params.video_width = grub_term_width (term);
        linux_params.video_height = grub_term_height (term);
        found = 1;
        break;
      }
      if (!found)
    {
      linux_params.video_cursor_x = 0;
      linux_params.video_cursor_y = 0;
      linux_params.video_width = 80;
      linux_params.video_height = 25;
    }
    }

  mmap_size = find_mmap_size ();
  /* Make sure that each size is aligned to a page boundary.  */
  cl_offset = ALIGN_UP (mmap_size + sizeof (linux_params), 4096);
  if (cl_offset < ((grub_size_t) linux_params.setup_sects << GRUB_DISK_SECTOR_BITS))
    cl_offset = ALIGN_UP ((grub_size_t) (linux_params.setup_sects
                     << GRUB_DISK_SECTOR_BITS), 4096);
  ctx.real_size = ALIGN_UP (cl_offset + maximal_cmdline_size, 4096);

#ifdef GRUB_MACHINE_EFI
  efi_mmap_size = find_efi_mmap_size ();
  if (efi_mmap_size == 0)
    return grub_errno;
#endif

  grub_dprintf ("linux", "real_size = %x, mmap_size = %x\n",
        (unsigned) ctx.real_size, (unsigned) mmap_size);

#ifdef GRUB_MACHINE_EFI
  grub_efi_mmap_iterate (grub_linux_boot_mmap_find, &ctx, 1);
  if (! ctx.real_mode_target)
    grub_efi_mmap_iterate (grub_linux_boot_mmap_find, &ctx, 0);
#else
  grub_mmap_iterate (grub_linux_boot_mmap_find, &ctx);
#endif
  grub_dprintf ("linux", "real_mode_target = %lx, real_size = %x, efi_mmap_size = %x\n",
                (unsigned long) ctx.real_mode_target,
        (unsigned) ctx.real_size,
        (unsigned) efi_mmap_size);

  if (! ctx.real_mode_target)
    return grub_error (GRUB_ERR_OUT_OF_MEMORY, "cannot allocate real mode pages");

  {
    grub_relocator_chunk_t ch;
    err = grub_relocator_alloc_chunk_addr (relocator, &ch,
                       ctx.real_mode_target,
                       (ctx.real_size + efi_mmap_size));
    if (err)
     return err;
    real_mode_mem = get_virtual_current_address (ch);
  }
  efi_mmap_buf = (grub_uint8_t *) real_mode_mem + ctx.real_size;

  grub_dprintf ("linux", "real_mode_mem = %p\n",
                real_mode_mem);

  ctx.params = real_mode_mem;

  *ctx.params = linux_params;
  ctx.params->cmd_line_ptr = ctx.real_mode_target + cl_offset;
  grub_memcpy ((char *) ctx.params + cl_offset, linux_cmdline,
           maximal_cmdline_size);

  grub_dprintf ("linux", "code32_start = %x\n",
        (unsigned) ctx.params->code32_start);

  ctx.e820_num = 0;
  if (grub_mmap_iterate (grub_linux_boot_mmap_fill, &ctx))
    return grub_errno;
  ctx.params->mmap_size = ctx.e820_num;

#ifdef GRUB_MACHINE_EFI
  {
    grub_efi_uintn_t efi_desc_size;
    grub_size_t efi_mmap_target;
    grub_efi_uint32_t efi_desc_version;
    err = grub_efi_finish_boot_services (&efi_mmap_size, efi_mmap_buf, NULL,
                     &efi_desc_size, &efi_desc_version);
    if (err)
      return err;

    /* Note that no boot services are available from here.  */
    efi_mmap_target = ctx.real_mode_target
      + ((grub_uint8_t *) efi_mmap_buf - (grub_uint8_t *) real_mode_mem);
    /* Pass EFI parameters.  */
    if (grub_le_to_cpu16 (ctx.params->version) >= 0x0208)
      {
    ctx.params->v0208.efi_mem_desc_size = efi_desc_size;
    ctx.params->v0208.efi_mem_desc_version = efi_desc_version;
    ctx.params->v0208.efi_mmap = efi_mmap_target;
    ctx.params->v0208.efi_mmap_size = efi_mmap_size;

#ifdef __x86_64__
    ctx.params->v0208.efi_mmap_hi = (efi_mmap_target >> 32);
#endif
      }
    else if (grub_le_to_cpu16 (ctx.params->version) >= 0x0206)
      {
    ctx.params->v0206.efi_mem_desc_size = efi_desc_size;
    ctx.params->v0206.efi_mem_desc_version = efi_desc_version;
    ctx.params->v0206.efi_mmap = efi_mmap_target;
    ctx.params->v0206.efi_mmap_size = efi_mmap_size;
      }
    else if (grub_le_to_cpu16 (ctx.params->version) >= 0x0204)
      {
    ctx.params->v0204.efi_mem_desc_size = efi_desc_size;
    ctx.params->v0204.efi_mem_desc_version = efi_desc_version;
    ctx.params->v0204.efi_mmap = efi_mmap_target;
    ctx.params->v0204.efi_mmap_size = efi_mmap_size;
      }
  }
#endif

  /* FIXME.  */
  /*  asm volatile ("lidt %0" : : "m" (idt_desc)); */
  state.ebp = state.edi = state.ebx = 0;
  state.esi = ctx.real_mode_target;
  state.esp = ctx.real_mode_target;
  state.eip = ctx.params->code32_start;
  return grub_relocator32_boot (relocator, state, 0);
}

static grub_err_t
grub_linux_unload (void)
{
  grub_dl_unref (my_mod);
  loaded = 0;
  grub_free (linux_cmdline);
  linux_cmdline = 0;
  return GRUB_ERR_NONE;
}

static grub_err_t
grub_cmd_mylinux (grub_command_t cmd __attribute__ ((unused)),
        int argc, char *argv[])
{
  grub_file_t file = 0;
  struct linux_kernel_header lh;
  grub_uint8_t setup_sects;
  grub_size_t real_size, prot_size, prot_file_size;
  grub_ssize_t len;
  int i;
  grub_size_t align, min_align;
  int relocatable;
  grub_uint64_t preferred_address = GRUB_LINUX_BZIMAGE_ADDR;

  grub_dl_ref (my_mod);

  if (argc == 0)
    {
      grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
      goto fail;
    }

  grub_printf ("%s (%s)\n", "Hello from my linux", argv[0]);

  file = grub_file_open (argv[0]);
  if (! file)
    goto fail;

  if (grub_file_read (file, &lh, sizeof (lh)) != sizeof (lh))
    {
      if (!grub_errno)
    grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
            argv[0]);
      goto fail;
    }

  if (lh.boot_flag != grub_cpu_to_le16_compile_time (0xaa55))
    {
      grub_error (GRUB_ERR_BAD_OS, "invalid magic number");
      goto fail;
    }

  if (lh.setup_sects > GRUB_LINUX_MAX_SETUP_SECTS)
    {
      grub_error (GRUB_ERR_BAD_OS, "too many setup sectors");
      goto fail;
    }

  /* FIXME: 2.03 is not always good enough (Linux 2.4 can be 2.03 and
     still not support 32-bit boot.  */
  if (lh.header != grub_cpu_to_le32_compile_time (GRUB_LINUX_MAGIC_SIGNATURE)
      || grub_le_to_cpu16 (lh.version) < 0x0203)
    {
      grub_error (GRUB_ERR_BAD_OS, "version too old for 32-bit boot"
#ifdef GRUB_MACHINE_PCBIOS
          " (try with `linux16')"
#endif
          );
      goto fail;
    }

  if (! (lh.loadflags & GRUB_LINUX_FLAG_BIG_KERNEL))
    {
      grub_error (GRUB_ERR_BAD_OS, "zImage doesn't support 32-bit boot"
#ifdef GRUB_MACHINE_PCBIOS
          " (try with `linux16')"
#endif
          );
      goto fail;
    }

  if (grub_le_to_cpu16 (lh.version) >= 0x0206)
    maximal_cmdline_size = grub_le_to_cpu32 (lh.cmdline_size) + 1;
  else
    maximal_cmdline_size = 256;

  if (maximal_cmdline_size < 128)
    maximal_cmdline_size = 128;

  setup_sects = lh.setup_sects;

  /* If SETUP_SECTS is not set, set it to the default (4).  */
  if (! setup_sects)
    setup_sects = GRUB_LINUX_DEFAULT_SETUP_SECTS;

  real_size = setup_sects << GRUB_DISK_SECTOR_BITS;
  prot_file_size = grub_file_size (file) - real_size - GRUB_DISK_SECTOR_SIZE;

  if (grub_le_to_cpu16 (lh.version) >= 0x205
      && lh.kernel_alignment != 0
      && ((lh.kernel_alignment - 1) & lh.kernel_alignment) == 0)
    {
      for (align = 0; align < 32; align++)
    if (grub_le_to_cpu32 (lh.kernel_alignment) & (1 << align))
      break;
      relocatable = grub_le_to_cpu32 (lh.relocatable);
    }
  else
    {
      align = 0;
      relocatable = 0;
    }

  if (grub_le_to_cpu16 (lh.version) >= 0x020a)
    {
      min_align = lh.min_alignment;
      prot_size = grub_le_to_cpu32 (lh.init_size);
      prot_init_space = page_align (prot_size);
      if (relocatable)
    preferred_address = grub_le_to_cpu64 (lh.pref_address);
      else
    preferred_address = GRUB_LINUX_BZIMAGE_ADDR;
    }
  else
    {
      min_align = align;
      prot_size = prot_file_size;
      preferred_address = GRUB_LINUX_BZIMAGE_ADDR;
      /* Usually, the compression ratio is about 50%.  */
      prot_init_space = page_align (prot_size) * 3;
    }

  if (allocate_pages (prot_size, &align,
              min_align, relocatable,
              preferred_address))
    goto fail;

  grub_memset (&linux_params, 0, sizeof (linux_params));
  grub_memcpy (&linux_params.setup_sects, &lh.setup_sects, sizeof (lh) - 0x1F1);

  linux_params.code32_start = prot_mode_target + lh.code32_start - GRUB_LINUX_BZIMAGE_ADDR;
  linux_params.kernel_alignment = (1 << align);
  linux_params.ps_mouse = linux_params.padding10 =  0;

  len = sizeof (linux_params) - sizeof (lh);
  if (grub_file_read (file, (char *) &linux_params + sizeof (lh), len) != len)
    {
      if (!grub_errno)
    grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
            argv[0]);
      goto fail;
    }

  linux_params.type_of_loader = GRUB_LINUX_BOOT_LOADER_TYPE;

  /* These two are used (instead of cmd_line_ptr) by older versions of Linux,
     and otherwise ignored.  */
  linux_params.cl_magic = GRUB_LINUX_CL_MAGIC;
  linux_params.cl_offset = 0x1000;

  linux_params.ramdisk_image = 0;
  linux_params.ramdisk_size = 0;

  linux_params.heap_end_ptr = GRUB_LINUX_HEAP_END_OFFSET;
  linux_params.loadflags |= GRUB_LINUX_FLAG_CAN_USE_HEAP;

  /* These are not needed to be precise, because Linux uses these values
     only to raise an error when the decompression code cannot find good
     space.  */
  linux_params.ext_mem = ((32 * 0x100000) >> 10);
  linux_params.alt_mem = ((32 * 0x100000) >> 10);

  /* Ignored by Linux.  */
  linux_params.video_page = 0;

  /* Only used when `video_mode == 0x7', otherwise ignored.  */
  linux_params.video_ega_bx = 0;

  linux_params.font_size = 16; /* XXX */

#ifdef GRUB_MACHINE_EFI
#ifdef __x86_64__
  if (grub_le_to_cpu16 (linux_params.version) < 0x0208 &&
      ((grub_addr_t) grub_efi_system_table >> 32) != 0)
    return grub_error(GRUB_ERR_BAD_OS,
              "kernel does not support 64-bit addressing");
#endif

  if (grub_le_to_cpu16 (linux_params.version) >= 0x0208)
    {
      linux_params.v0208.efi_signature = GRUB_LINUX_EFI_SIGNATURE;
      linux_params.v0208.efi_system_table = (grub_uint32_t) (grub_addr_t) grub_efi_system_table;
#ifdef __x86_64__
      linux_params.v0208.efi_system_table_hi = (grub_uint32_t) ((grub_uint64_t) grub_efi_system_table >> 32);
#endif
    }
  else if (grub_le_to_cpu16 (linux_params.version) >= 0x0206)
    {
      linux_params.v0206.efi_signature = GRUB_LINUX_EFI_SIGNATURE;
      linux_params.v0206.efi_system_table = (grub_uint32_t) (grub_addr_t) grub_efi_system_table;
    }
  else if (grub_le_to_cpu16 (linux_params.version) >= 0x0204)
    {
      linux_params.v0204.efi_signature = GRUB_LINUX_EFI_SIGNATURE_0204;
      linux_params.v0204.efi_system_table = (grub_uint32_t) (grub_addr_t) grub_efi_system_table;
    }
#endif

  /* The other parameters are filled when booting.  */

  grub_file_seek (file, real_size + GRUB_DISK_SECTOR_SIZE);

  grub_dprintf ("linux", "bzImage, setup=0x%x, size=0x%x\n",
        (unsigned) real_size, (unsigned) prot_size);

  /* Look for memory size and video mode specified on the command line.  */
  linux_mem_size = 0;
  for (i = 1; i < argc; i++)
#ifdef GRUB_MACHINE_PCBIOS
    if (grub_memcmp (argv[i], "vga=", 4) == 0)
      {
    /* Video mode selection support.  */
    char *val = argv[i] + 4;
    unsigned vid_mode = GRUB_LINUX_VID_MODE_NORMAL;
    struct grub_vesa_mode_table_entry *linux_mode;
    grub_err_t err;
    char *buf;

    grub_dl_load ("vbe");

    if (grub_strcmp (val, "normal") == 0)
      vid_mode = GRUB_LINUX_VID_MODE_NORMAL;
    else if (grub_strcmp (val, "ext") == 0)
      vid_mode = GRUB_LINUX_VID_MODE_EXTENDED;
    else if (grub_strcmp (val, "ask") == 0)
      {
        grub_puts_ (N_("Legacy `ask' parameter no longer supported."));

        /* We usually would never do this in a loader, but "vga=ask" means user
           requested interaction, so it can't hurt to request keyboard input.  */
        grub_wait_after_message ();

        goto fail;
      }
    else
      vid_mode = (grub_uint16_t) grub_strtoul (val, 0, 0);

    switch (vid_mode)
      {
      case 0:
      case GRUB_LINUX_VID_MODE_NORMAL:
        grub_env_set ("gfxpayload", "text");
        grub_printf_ (N_("%s is deprecated. "
                 "Use set gfxpayload=%s before "
                 "linux command instead.\n"),
              argv[i], "text");
        break;

      case 1:
      case GRUB_LINUX_VID_MODE_EXTENDED:
        /* FIXME: support 80x50 text. */
        grub_env_set ("gfxpayload", "text");
        grub_printf_ (N_("%s is deprecated. "
                 "Use set gfxpayload=%s before "
                 "linux command instead.\n"),
              argv[i], "text");
        break;
      default:
        /* Ignore invalid values.  */
        if (vid_mode < GRUB_VESA_MODE_TABLE_START ||
        vid_mode > GRUB_VESA_MODE_TABLE_END)
          {
        grub_env_set ("gfxpayload", "text");
        /* TRANSLATORS: "x" has to be entered in, like an identifier,
           so please don't use better Unicode codepoints.  */
        grub_printf_ (N_("%s is deprecated. VGA mode %d isn't recognized. "
                 "Use set gfxpayload=WIDTHxHEIGHT[xDEPTH] "
                 "before linux command instead.\n"),
                 argv[i], vid_mode);
        break;
          }

        linux_mode = &grub_vesa_mode_table[vid_mode
                           - GRUB_VESA_MODE_TABLE_START];

        buf = grub_xasprintf ("%ux%ux%u,%ux%u",
                 linux_mode->width, linux_mode->height,
                 linux_mode->depth,
                 linux_mode->width, linux_mode->height);
        if (! buf)
          goto fail;

        grub_printf_ (N_("%s is deprecated. "
                 "Use set gfxpayload=%s before "
                 "linux command instead.\n"),
             argv[i], buf);
        err = grub_env_set ("gfxpayload", buf);
        grub_free (buf);
        if (err)
          goto fail;
      }
      }
    else
#endif /* GRUB_MACHINE_PCBIOS */
    if (grub_memcmp (argv[i], "mem=", 4) == 0)
      {
    char *val = argv[i] + 4;

    linux_mem_size = grub_strtoul (val, &val, 0);

    if (grub_errno)
      {
        grub_errno = GRUB_ERR_NONE;
        linux_mem_size = 0;
      }
    else
      {
        int shift = 0;

        switch (grub_tolower (val[0]))
          {
          case 'g':
        shift += 10;
        /* FALLTHROUGH */
          case 'm':
        shift += 10;
        /* FALLTHROUGH */
          case 'k':
        shift += 10;
        /* FALLTHROUGH */
          default:
        break;
          }

        /* Check an overflow.  */
        if (linux_mem_size > (~0UL >> shift))
          linux_mem_size = 0;
        else
          linux_mem_size <<= shift;
      }
      }
    else if (grub_memcmp (argv[i], "quiet", sizeof ("quiet") - 1) == 0)
      {
    linux_params.loadflags |= GRUB_LINUX_FLAG_QUIET;
      }

  /* Create kernel command line.  */
  linux_cmdline = grub_zalloc (maximal_cmdline_size + 1);
  if (!linux_cmdline)
    goto fail;
  grub_memcpy (linux_cmdline, LINUX_IMAGE, sizeof (LINUX_IMAGE));
  grub_create_loader_cmdline (argc, argv,
                  linux_cmdline
                  + sizeof (LINUX_IMAGE) - 1,
                  maximal_cmdline_size
                  - (sizeof (LINUX_IMAGE) - 1));
  if(appended_args_count > 0)
  { // Append our command line args)
    //find offset in `linux_cmdline` to begin appending
    unsigned offset = grub_strlen(linux_cmdline);
    if(offset + 2 < maximal_cmdline_size)
    {
      linux_cmdline[offset] = ' '; // Replase 0 -> space to append new args
      grub_create_loader_cmdline(appended_args_count, appended_args,
        linux_cmdline + offset + 1, maximal_cmdline_size - offset - 2);
    }
  }// That's all falks)

  len = prot_file_size;
  if (grub_file_read (file, prot_mode_mem, len) != len && !grub_errno)
    grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
        argv[0]);

  if (grub_errno == GRUB_ERR_NONE)
    {
      grub_loader_set (grub_linux_boot, grub_linux_unload,
               0 /* set noreturn=0 in order to avoid grub_console_fini() */);
      loaded = 1;
    }

 fail:

  if (file)
    grub_file_close (file);

  if (grub_errno != GRUB_ERR_NONE)
    {
      grub_dl_unref (my_mod);
      loaded = 0;
    }

  return grub_errno;
}

static grub_err_t
grub_cmd_myinitrd (grub_command_t cmd __attribute__ ((unused)),
         int argc, char *argv[])
{
  grub_size_t size = 0, aligned_size = 0;
  grub_addr_t addr_min, addr_max;
  grub_addr_t addr;
  grub_err_t err;
  struct grub_linux_initrd_context initrd_ctx = { 0, 0, 0 };

  if (argc == 0)
    {
      grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
      goto fail;
    }

  if (! loaded)
    {
      grub_error (GRUB_ERR_BAD_ARGUMENT, N_("you need to load the kernel first"));
      goto fail;
    }

  grub_printf ("%s (%s)\n", "Hello from my initrd", argv[0]);

  if (grub_initrd_init (argc, argv, &initrd_ctx))
    goto fail;

  size = grub_get_initrd_size (&initrd_ctx);
  aligned_size = ALIGN_UP (size, 4096);

  /* Get the highest address available for the initrd.  */
  if (grub_le_to_cpu16 (linux_params.version) >= 0x0203)
    {
      addr_max = grub_cpu_to_le32 (linux_params.initrd_addr_max);

      /* XXX in reality, Linux specifies a bogus value, so
     it is necessary to make sure that ADDR_MAX does not exceed
     0x3fffffff.  */
      if (addr_max > GRUB_LINUX_INITRD_MAX_ADDRESS)
    addr_max = GRUB_LINUX_INITRD_MAX_ADDRESS;
    }
  else
    addr_max = GRUB_LINUX_INITRD_MAX_ADDRESS;

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

  /* Linux 2.3.xx has a bug in the memory range check, so avoid
     the last page.
     Linux 2.2.xx has a bug in the memory range check, which is
     worse than that of Linux 2.3.xx, so avoid the last 64kb.  */
  addr_max -= 0x10000;

  addr_min = (grub_addr_t) prot_mode_target + prot_init_space;

  /* Put the initrd as high as possible, 4KiB aligned.  */
  addr = (addr_max - aligned_size) & ~0xFFF;

  if (addr < addr_min)
    {
      grub_error (GRUB_ERR_OUT_OF_RANGE, "the initrd is too big");
      goto fail;
    }

  {
    grub_relocator_chunk_t ch;
    err = grub_relocator_alloc_chunk_align (relocator, &ch,
                        addr_min, addr, aligned_size,
                        0x1000,
                        GRUB_RELOCATOR_PREFERENCE_HIGH,
                        1);
    if (err)
      return err;
    initrd_mem = get_virtual_current_address (ch);
    initrd_mem_target = get_physical_target_address (ch);
  }

  if (grub_initrd_load (&initrd_ctx, argv, initrd_mem))
    goto fail;

  grub_dprintf ("linux", "Initrd, addr=0x%x, size=0x%x\n",
        (unsigned) addr, (unsigned) size);

  linux_params.ramdisk_image = initrd_mem_target;
  linux_params.ramdisk_size = size;
  linux_params.root_dev = 0x0100; /* XXX */

 fail:
  grub_initrd_close (&initrd_ctx);

  return grub_errno;
}

static grub_command_t cmd_mylinux, cmd_myinitrd;
// END FROM loader/i386/linux.c

static grub_extcmd_t cmd;


GRUB_MOD_INIT(append)
{
  cmd = grub_register_extcmd("append", grub_cmd_append, 0, 0,
                  N_("Setup (or show) arguments to append to kernel command line."), 0);

  cmd_mylinux = grub_register_command("linux", grub_cmd_mylinux,
                     0, N_("Load Linux."));
  cmd_myinitrd = grub_register_command("initrd", grub_cmd_myinitrd,
                      0, N_("Load initrd."));
  my_mod = mod;
}

GRUB_MOD_FINI(append)
{
  grub_unregister_extcmd(cmd);
  grub_unregister_command(cmd_mylinux);
  grub_unregister_command(cmd_myinitrd);
  clean_args();
}