Hello!
We have a serious problem with installing onto partitions (e.g.
grub-install /dev/sda1) and drives with geometry that doesn't leave
enough space for core.img to be embedded before the first partition.
While it's not a desirable configuration, it should work, but it
doesn't.
Either we should write sector 2 before the core.img is checked for
readability or we should delay patching sector 2 in memory until the
verification is done. Otherwise, the verification will fail.
Delayed patching changes nothing in terms of I/O but needs a longer
patch and won't scale well if we want to put more information into
sector 2, as we'll need to cache more data.
Writing sector 2 early is less intrusive in terms of code, but may be
slower e.g. on floppies. It's probably more reliable because we verify
that the modified sector 2 made it to the filesystem.
I tend to prefer the later ("write early") approach, but I'd like to see
some feedback before I commit it.
Both proposed patches are attached.
--
Regards,
Pavel Roskin
diff --git a/util/i386/pc/grub-setup.c b/util/i386/pc/grub-setup.c
index 62c1bf1..3e9b4b5 100644
--- a/util/i386/pc/grub-setup.c
+++ b/util/i386/pc/grub-setup.c
@@ -101,6 +101,7 @@ setup (const char *dir,
grub_uint16_t *boot_drive_check;
struct boot_blocklist *first_block, *block;
grub_int32_t *install_dos_part, *install_bsd_part;
+ grub_int32_t dos_part, bsd_part;
char *tmp_img;
int i;
grub_disk_addr_t first_sector;
@@ -283,27 +284,24 @@ setup (const char *dir,
{
struct grub_pc_partition *pcdata =
root_dev->disk->partition->data;
- *install_dos_part
- = grub_cpu_to_le32 (pcdata->dos_part);
- *install_bsd_part
- = grub_cpu_to_le32 (pcdata->bsd_part);
+ dos_part = grub_cpu_to_le32 (pcdata->dos_part);
+ bsd_part = grub_cpu_to_le32 (pcdata->bsd_part);
}
else if (strcmp (root_dev->disk->partition->partmap->name,
"gpt_partition_map") == 0)
{
- *install_dos_part = grub_cpu_to_le32 (root_dev->disk->partition->index);
- *install_bsd_part = grub_cpu_to_le32 (-1);
+ dos_part = grub_cpu_to_le32 (root_dev->disk->partition->index);
+ bsd_part = grub_cpu_to_le32 (-1);
}
else
grub_util_error ("No PC style partitions found");
}
else
- *install_dos_part = *install_bsd_part = grub_cpu_to_le32 (-1);
+ dos_part = bsd_part = grub_cpu_to_le32 (-1);
}
grub_util_info ("dos partition is %d, bsd partition is %d",
- grub_le_to_cpu32 (*install_dos_part),
- grub_le_to_cpu32 (*install_bsd_part));
+ grub_le_to_cpu32 (dos_part), grub_le_to_cpu32 (bsd_part));
/* If the destination device can have partitions and it is the MBR,
try to embed the core image into after the MBR. */
@@ -316,6 +314,9 @@ setup (const char *dir,
{
grub_util_info ("will embed the core image at sector 0x%llx", embed_region.start);
+ *install_dos_part = dos_part;
+ *install_bsd_part = bsd_part;
+
/* The first blocklist contains the whole sectors. */
first_block->start = grub_cpu_to_le64 (embed_region.start + 1);
first_block->len = grub_cpu_to_le16 (core_sectors - 1);
@@ -485,6 +486,9 @@ setup (const char *dir,
the boot device. */
*root_drive = 0xFF;
+ *install_dos_part = dos_part;
+ *install_bsd_part = bsd_part;
+
/* Write the first two sectors of the core image onto the disk. */
grub_util_info ("opening the core image `%s'", core_path);
fp = fopen (core_path, "r+b");
diff --git a/util/i386/pc/grub-setup.c b/util/i386/pc/grub-setup.c
index 62c1bf1..d2c5a73 100644
--- a/util/i386/pc/grub-setup.c
+++ b/util/i386/pc/grub-setup.c
@@ -365,6 +365,15 @@ setup (const char *dir,
/* The core image must be put on a filesystem unfortunately. */
grub_util_info ("will leave the core image on the filesystem");
+ /* Write the second sector of the core image onto the disk. */
+ grub_util_info ("opening the core image `%s'", core_path);
+ fp = fopen (core_path, "r+b");
+ if (! fp)
+ grub_util_error ("Cannot open `%s'", core_path);
+ grub_util_write_image_at (core_img + GRUB_DISK_SECTOR_SIZE,
+ GRUB_DISK_SECTOR_SIZE, GRUB_DISK_SECTOR_SIZE, fp);
+ fclose (fp);
+
/* Make sure that GRUB reads the identical image as the OS. */
tmp_img = xmalloc (core_size);
core_path_dev = grub_util_get_path (DEFAULT_DIRECTORY, core_file);
@@ -485,13 +494,13 @@ setup (const char *dir,
the boot device. */
*root_drive = 0xFF;
- /* Write the first two sectors of the core image onto the disk. */
+ /* Write the first sector of the core image onto the disk. */
grub_util_info ("opening the core image `%s'", core_path);
fp = fopen (core_path, "r+b");
if (! fp)
grub_util_error ("Cannot open `%s'", core_path);
- grub_util_write_image (core_img, GRUB_DISK_SECTOR_SIZE * 2, fp);
+ grub_util_write_image (core_img, GRUB_DISK_SECTOR_SIZE, fp);
fclose (fp);
/* Write the boot image onto the disk. */
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