Re: [PATCH] gptsync

[Peter Cros]

Hi,

I have been playing with grub gptsync, on apple intel mac with GUID partitioned 8 GB usb stick, 8 partitions. #1 is the standard fat32 EFI system part for macs.

I am comparing with the gptsync utility from linux, or rEFIt gptsync, currently used for macs booting pc-bios bootloader.

It is working to allow selection of GPT partions for MBR 2, 3, 4 but some of the numbers look wrong. I have not tried setting flags.

grub gptsync is not handling MBR partition table 1 the same way as current linux or refit gptsync, which puts GPT partition 1 (EFI system FAT32) in MBR part1.

GPT Partions are

(512 byte sectors)

Current GPT partition table:

 #      Start LBA      End LBA  Type

 1             40       409639  EFI System (FAT)

 2         409640      2395367  Mac OS X HFS+

 3        2395368      4573255  Mac OS X HFS+

 4        4835400      7141399  Mac OS X HFS+

 5        7403544      9965767  Mac OS X HFS+

 6       10227912     13046359  Mac OS X HFS+

 7       13308504     15642623  Mac OS X HFS+

 8       15904768     15949783  Mac OS X HFS+

There seems to be agreement about start and end on MBR table partitions 2 3 4, using grub> gptsync (hd0) 2 3 4.

Other bytes differ (type, flags).

This is after grub> gptsync (hd0) 2 3 4 

(MBR part1 was initially set by linux gptsync)

address@hidden:~$ sudo hexdump -Cn80 -s432 /dev/sdb

[sudo] password for pxw:

000001b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|

000001c0  02 00 ee 7f 0e 19 01 00  00 00 27 40 06 00 00 7f  |..........'@....|

000001d0  0f 19 83 1a 2d 95 28 40  06 00 c0 4c 1e 00 00 1a  |....-.(@...L....|

000001e0  2e 95 83 ab 57 1c e8 8c  24 00 60 3b 21 00 00 fc  |....W...$.`;!...|

000001f0  59 2c 83 87 63 bc 48 c8  49 00 d0 2f 23 00 55 aa  |Y,..c.H.I../#.U.|

00000200

Then as seen in linux gptsync, 

Current MBR partition table:

 # A    Start LBA      End LBA  Type

 1              1       409639  ee  EFI Protective

 2         409640      2395367  83  Linux

 3        2395368      4573255  83  Linux

 4        4835400      7141399  83  Linux

Status: MBR table must be updated.

Proposed new MBR partition table:

 # A    Start LBA      End LBA  Type

 1              1       409639  ee  EFI Protective

 2 *       409640      2395367  af  Mac OS X HFS+

 3        2395368      4573255  af  Mac OS X HFS+

 4        4835400      7141399  af  Mac OS X HFS+

May I update the MBR as printed above? [y/N] y

Yes

address@hidden:~$ sudo hexdump -Cn80 -s432 /dev/sdb

000001b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 fe  |................|

000001c0  ff ff ee fe ff ff 01 00  00 00 27 40 06 00 80 fe  |..........'@....|

000001d0  ff ff af fe ff ff 28 40  06 00 c0 4c 1e 00 00 fe  |......(@...L....|

000001e0  ff ff af fe ff ff e8 8c  24 00 60 3b 21 00 00 fe  |........$.`;!...|

000001f0  ff ff af fe ff ff 48 c8  49 00 d0 2f 23 00 55 aa  |......H.I../#.U.|

00000200

-- 

Cros (pxw)