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Feature #11974

closed

loader: add support for hybrid PMBR for GPT partition table

Added by Toomas Soome about 2 years ago. Updated almost 2 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Category:
bootloader
Start date:
Due date:
% Done:

100%

Estimated time:
Difficulty:
Medium
Tags:
Gerrit CR:

Description

Hybrid PMBR is PMBR table with extra partition entries. We still have partition type 0xEE, starting with absolute sector 0. But while UEFI specification conforming PMBR does not have any other partitions defined, the hybrid PMBR does. Such hybrid table is used to provide support for older windows setups with apple bootcamp.

Sample hybrid table:

tsoome@beastie:~$ mdb mbr.dd 
> ::load disk_label
> ::mbr
Format: unknown
Signature: 0xaa55 (valid)
UniqueMBRDiskSignature: 0

PART TYPE                  ACTIVE  STARTCHS    ENDCHS      SECTOR     NUMSECT  
0    EFI_PMBR:0xee         0       1023/254/63 1023/254/63 1          409639   
1    0xff                  0       1023/254/63 1023/254/63 409640     978508408
2    FDISK_EXT_WIN:0xc     0       1023/254/63 1023/254/63 978918048  31250000 
3    0xff                  0       1023/254/63 1023/254/63 1010168048 32       
> 

Testing done: confirmed we do get GPT and not MBR table.

Actions #1

Updated by Toomas Soome about 2 years ago

  • Description updated (diff)
Actions #2

Updated by Toomas Soome about 2 years ago

  • Description updated (diff)
Actions #3

Updated by Electric Monk almost 2 years ago

  • Status changed from In Progress to Closed
  • % Done changed from 90 to 100

git commit 28a0ed2750bebd6af4595605f02abded76fbef18

commit  28a0ed2750bebd6af4595605f02abded76fbef18
Author: Toomas Soome <tsoome@me.com>
Date:   2020-01-17T06:43:17.000Z

    11974 loader: add support for hybrid PMBR for GPT partition table
    Reviewed by: Robert Mustacchi <rm@fingolfin.org>
    Approved by: Dan McDonald <danmcd@joyent.com>

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