bugGNU GRUB - Bugs: bug #38284, GRUB should provide option to swap...


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bug #38284: GRUB should provide option to swap partition order

Submitted by:  Ulf Zibis <ulfzibis>
Submitted on:  Fri 08 Feb 2013 12:45:51 AM UTC  
Votes:  40  
Category: BootingSeverity: Major
Priority: 5 - NormalItem Group: Feature Request
Status: NonePrivacy: Public
Assigned to: NoneOriginator Name: Ulf Zibis
Open/Closed: OpenRelease: 
Release: Bazaar - trunkReproducibility: Every Time
Planned Release: None

Mon 11 Feb 2013 10:58:12 PM UTC, comment #4:

See here:

Ulf Zibis <ulfzibis>
Mon 11 Feb 2013 10:43:37 PM UTC, comment #3:

Pooh, how often should I explain, that there is nothing to fix in boot.ini?

Here it is. What would you think to repair here?

[boot loader]
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect

Ulf Zibis <ulfzibis>
Mon 11 Feb 2013 08:56:02 PM UTC, comment #2:

Have you tried fixing your boot.ini? Windows doesn't identify partitions by numbers other than in ntldr and fixing boot.ini will take care of this.

Vladimir Serbinenko <phcoder>
Project Administrator
Mon 11 Feb 2013 02:57:45 PM UTC, comment #1:

Please forget, what I have written for grub.cfg. I wasn't aware, that partitions normally are determined by their UUID, so the assignment should work even if partitions are swapped.

So I suggest to extend the os-prober script similar like the following:
(should be controlled by a new etc/default/grub entry)

if [ x"${swapped_part_1}" = xy && x"${swapped_part_2}" = xy ]; then
parttool $swapped_part_1 swap-order $swapped_part_2
set swapped_part_1=
set swapped_part_2=
save_env swapped_part_1
save_env swapped_part_2

menuentry 'Windows XP on sda1' {

menuentry 'Windows XP OLD on sda3' {
set swapped_part_1='hd0,msdos1'
set swapped_part_2=${root}
parttool $swapped_part_1 swap-order $swapped_part_2
save_env swapped_part_1
save_env swapped_part_2
chainloader +1

A first draft, of what should be added to grub-core/parttool/msdospart.c :
(I do not have any environment to build GRUB, so hopefully others have)
static struct grub_parttool_argdesc grub_pcpart_swapargs[] =
{"swap-order", N_("Swap the order in partition table"), GRUB_PARTTOOL_ARG_VAL},
{0, 0, 0}

static grub_err_t grub_pcpart_swap (const grub_device_t dev1,
const struct grub_parttool_args *args)
grub_device_t dev2 = parse (args[0]); // TODO: replace parse() by valid code
grub_partition_t part1, part2;
int index1, index2;
struct grub_msdos_partition_mbr mbr;
struct grub_msdos_partition_entry entry;

part1 = dev1->disk->partition;
part2 = dev2->disk->partition;
index1 = part1->index;
index2 = part2->index;

if (dev1->disk != dev2->disk)
return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("partitions must be on same disk"));
if (index1 >= 4 || index2 >= 4)
return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("logical partition not allowed"));

dev1->disk->partition = part1->parent;

/* Read the MBR. */
if (grub_disk_read (dev1->disk, 0, 0, sizeof (mbr), &mbr))
dev1->disk->partition = part1;
return grub_errno;

entry = mbr.entries[index1];
mbr.entries[index1] = mbr.entries[index2];
mbr.entries[index2] = entry;
grub_printf_ (N_("Partitions %d, %d are swapped now. \n"), index1, index2);

/* Write the MBR. */
grub_disk_write (dev1->disk, 0, 0, sizeof (mbr), &mbr);

dev1->disk->partition = part1;


Ulf Zibis <ulfzibis>
Fri 08 Feb 2013 12:45:51 AM UTC, original submission:

After several unsuccessful tries with different combinations of command "parttool (partition) hidden+-", I've found a possibility to have 2 WinXP installations, both originally installed on sda1 aka "C:", alternatively running on one disk. I copied my old Windows XP partition from sda1 to sda2. After a fresh new Windows XP installation was installed to sda1.

First I tried this:

It works for to boot the Windows installation on sda1, but it dosn't work for the one on sda2 (~ 10 seconds after WinXP boot screen I got a blue-screen).
Surely it should work to boot Windows from sda2, if that Windows installation was originally installed to sda2 aka "D:", which is not the case here. There may be a chance, to tweak Windows registry with advanced expert knowledge, to change the Windows drive letter mapping to make the Windows system volume named as "D:", as if it was originally installed so, but this is hard work.

So the only thing I found out, that works, is to swap the order of those partitions in the partition table (print from sfdisk):
Device Boot Start End #cyls #blocks Id System
/dev/sda1 * 0+ 3038 3039- 24410736 7 HPFS/NTFS/exFAT
/dev/sda2 16418 19456 3039 24410767+ 7 HPFS/NTFS/exFAT
/dev/sda3 3039 5390 2352 18892440 83 Linux
exchange/toggle with:
/dev/sda1 16418 19456 3039 24410767+ 7 HPFS/NTFS/exFAT
/dev/sda2 * 0+ 3038 3039- 24410736 7 HPFS/NTFS/exFAT
/dev/sda3 3039 5390 2352 18892440 83 Linux

Unfortunately GRUB can't do that until now, so hereby I suggest an additional
option e.g.:

parttool (hd0,1) swap-order (hd0,2)

The option should include swapping the volume-IDs in the menu entries in grub.cfg as well, so they would again match correctly.

So initially, Grub menu should look like:
Extended Options for Ubuntu
Memory test ...
Microsoft Windows XP Professional NEW (on /dev/sda1)
Microsoft Windows XP Professional OLD (on /dev/sda2)
But after once booting into "Windows XP OLD", according my RFE, after reboot, the menu should look like:
Extended Options for Ubuntu
Memory test ...
Microsoft Windows XP Professional NEW (on /dev/sda2) <-- note the swapped no.
Microsoft Windows XP Professional OLD (on /dev/sda1)



Ulf Zibis <ulfzibis>


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  • -unavailable- added by phcoder (Posted a comment)
  • -unavailable- added by ulfzibis (Submitted the item)
  • -unavailable- added by ulfzibis

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    Fri 08 Feb 2013 12:45:51 AM UTCulfzibisCarbon-Copy-=>Added ulfzibis

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