[Bug 1051154] Re: mdraid1x core image too large for minimal MBR

[Colin Watson]

Well, I updated the description for now, but it's not clear that a
core.img with mdraid1x is actually over the limit:

(precise-amd64)root at sarantium:~# grub-mkimage -O i386-pc --output=core.img biosdisk ext2 part_msdos mdraid1x
(precise-amd64)root at sarantium:~# ls -l core.img
-rw-r--r-- 1 root root 29451 Sep 18 16:06 core.img

(quantal-amd64)root at sarantium:~# grub-mkimage -O i386-pc --output=core.img biosdisk ext2 part_msdos diskfilter mdraid1x
(quantal-amd64)root at sarantium:~# ls -l core.img
-rw-r--r-- 1 root root 31362 Sep 18 16:06 core.img

Since the first sector contains the MBR and partition table, that leaves 62 sectors == 31744 bytes, which should be enough.  
Can you confirm that the second of these matches the size of your /boot/grub/core.img?  It would also be helpful if you could attach the first 32KB of each disk:

  sudo hd -n32768 /dev/sda >sda.start
  sudo hd -n32768 /dev/sdb >sdb.start

** Changed in: grub2 (Ubuntu)
     Assignee: (unassigned) => Colin Watson (cjwatson)

** Summary changed:

- mdraid1x core image too large for minimal MBR
+ mdraid1x core image too large for minimal MBR?

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https://bugs.launchpad.net/bugs/1051154

Title:
  mdraid1x core image too large for minimal MBR?

Status in “grub2” package in Ubuntu:
  Triaged

Bug description:
  I've been running Quantal on a machine for a while now, and everything
  has been smooth.

  However, I just took the recent grub2 & kernel updates which seemed to break grub2:
  * grub-pc-bin:amd64 (1.99-22ubuntu2, 2.00-4ubuntu1)
  * linux-image-3.5.0-14-generic:amd64 (3.5.0-14.16, 3.5.0-14.19)

  Grub2 now complains:

  /usr/sbin/grub-bios-setup: warning: your embedding area is unusually small.  core.img won't fit in it..
  /usr/sbin/grub-bios-setup: error: embedding is not possible, but this is required for RAID and LVM install.
  /usr/sbin/grub-bios-setup: warning: your embedding area is unusually small.  core.img won't fit in it..
  /usr/sbin/grub-bios-setup: error: embedding is not possible, but this is required for RAID and LVM install.

  
  Are there any workarounds for this?

  
  This is a very simple install, just md RAID1, with one dumb partition, no LVM.

  $ sudo parted /dev/sda
  GNU Parted 2.3
  Using /dev/sda
  Welcome to GNU Parted! Type 'help' to view a list of commands.
  (parted) print                                                            
  Model: ATA HDS725050KLA360 (scsi)
  Disk /dev/sda: 500GB
  Sector size (logical/physical): 512B/512B
  Partition Table: msdos

  Number  Start   End    Size   Type     File system  Flags
   1      32.3kB  500GB  500GB  primary  ext4         raid


  $ sudo parted /dev/sdb
  GNU Parted 2.3
  Using /dev/sdb
  Welcome to GNU Parted! Type 'help' to view a list of commands.
  (parted) print                                                            
  Model: ATA HDS725050KLA360 (scsi)
  Disk /dev/sdb: 500GB
  Sector size (logical/physical): 512B/512B
  Partition Table: msdos

  Number  Start   End    Size   Type     File system  Flags
   1      32.3kB  500GB  500GB  primary  ext4         boot, raid


  $ uname -ar
  Linux machine-1 3.5.0-14-generic #16-Ubuntu SMP Mon Sep 10 21:57:14 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

  ProblemType: Bug
  DistroRelease: Ubuntu 12.10
  Package: grub2 (not installed)
  ProcVersionSignature: Ubuntu 3.5.0-14.16-generic 3.5.3
  Uname: Linux 3.5.0-14-generic x86_64
  ApportVersion: 2.5.1-0ubuntu7
  Architecture: amd64
  Date: Fri Sep 14 23:38:19 2012
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: grub2
  UpgradeStatus: Upgraded to quantal on 2012-03-05 (194 days ago)

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