[Bug 1237519] Re: Grub2 fails to install to non-standard device path

[Colin Watson]

I investigated this with the aid of some kindly-provided remote access
and gdb.

GRUB needs to be able to find the start sector of each partition within
a disk in order to accurately match up OS-level devices with GRUB
devices.  On Linux, it uses the HDIO_GETGEO ioctl to do this; although
most of the information returned by that ioctl is obsolete, it returns
the start sector.  Most Linux block device drivers implement this ioctl;
unfortunately the FusionIO block device driver does not, and therefore
GRUB has no way to safely identify /dev/fioa1.

Since this ioctl is typically rather easy to implement (you need to
implement the "getgeo" member of block_device_operations), I think this
should be fixed in the FusionIO driver.  If you don't have meaningful
cylinder/head/sector-type information to fill in, you can probably fake
it up, perhaps in the same way that drivers/block/umem.c does.  The
start sector is filled in from generic code in block/ioctl.c.

There is only one other way I know of to get the start sector of a
partition from userspace, and that's to read its "start" attribute from
sysfs.  However, that's considerably more cumbersome to do from C code,
and I'd prefer to avoid that if at all possible.  If you could add this
fairly simple interface to the FusionIO driver, it would make things
considerably easier.  Alternatively, if there's some other interface you
can suggest that's generic in Linux rather than being FusionIO-specific,
I'd be happy to look into using that.

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https://bugs.launchpad.net/bugs/1237519

Title:
  Grub2 fails to install to non-standard device path

Status in “grub-installer” package in Ubuntu:
  Fix Released
Status in “grub2” package in Ubuntu:
  Fix Released
Status in “grub-installer” source package in Precise:
  New
Status in “grub2” source package in Precise:
  New

Bug description:
  Running the Ubuntu Server installer in UEFI mode fails to install the
  Grub bootloader.  Attached is the syslog output that shows grub-
  installer failed with error code 1.  I have seen this on Ubuntu 12.04,
  12.10, and 13.04.  I believe the problem is that Grub is looking for
  device paths that match something like '/dev/sdX' or '/dev/hdX' but
  the device I am installing to does not follow that convention.

  The reason I believe it is looking for specific devices paths is if,
  during installation after my device has been partitioned, I escape
  into the shell (using alt+f2) and create a hard link from my device
  name and its partitions, to a device name that matches 'sdX', then
  Grub begins to install.  For example, if my device name is /dev/fioa
  and has partitions /dev/fioa1, /dev/fioa2, and /dev/fioa3, I map those
  partitions to something like /dev/sdc, /dev/sdc1, /dev/sdc2, and
  /dev/sdc3 and continue with the installation onto /dev/sdc.  By doing
  this, Grub will begin to install on the device.

  Possibly useful background information:

  - The operating system and all files install just fine without
  problem, it is the last step of installing the bootloader that fails.

  - In order to have the device recognized during installation, I either
  need to run 'insmod' from a terminal or we have to manually modify
  initrd to include our .ko file because it is not a standard disk
  driver.  Using either method does not affect the outcome of Grub2
  failing to install.

  - Even though grub begins to install after creating the hard links
  mentioned above, it does not finish successfully due to the linked
  paths (e.g. /dev/sdc) not being in the device map.  That is a separate
  issue, but may be expected behavior and would likely need a separate
  ticket if it needed to be reported at all.

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