GRUB-EFI bootloader for USB booting 64bit EFI and UEFI machines.

Updated:  2015.02.05
Revision: 0.02

Files and checksums:

$ shasum EFI/boot/bootx64.efi 
093b2e05d8ad4c2bb8ca01d01c15fdaa6ff50174  EFI/boot/bootx64.efi
$ shasum EFI/boot/unicode.pf2 
74bf975b64be55f4e1b2abac4320966782f8d388  EFI/boot/unicode.pf2
$ shasum EFI/boot/grub.cfg 
d850dd77e88f2880ddfaf31a5f1765916e519784  EFI/boot/grub.cfg

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More info on GNU GRUB can be found here::
http://www.gnu.org/software/grub/

Source code:
http://www.gnu.org/software/grub/grub-download.html
http://savannah.gnu.org/git/?group=grub

Pre-compiled files from the GNOME Partition Editor.
http://gparted.org/

Downloaded version: gparted-live-0.20.0-2-amd64.zip
http://sourceforge.net/projects/gparted/

Sample grub.cfg provided with default for Micro Core Linux.
Plus additional option for Micron M550 Firmware updater.

Please note: using GRUB to boot the Micron firmware updater is unsupported.
Use this option at your own risk.

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Installation procedure for OS X and other *nix:

1. Format the USB flash drive (in some cases an SD card can be used). 

Format the USB flash drive as FAT32 (MS-DOS in OS X Disk Utility).
- use Partition Map type: Master Boot Record.
- select a volume name - in this case we use: EFIBOOT

Once formatting is complete, the volume should be mounted as EFIBOOT.

2. To install the EFI bootloader, open the folder containing GRUB-EFI files:

 * EFI/boot/unicode.pf2
 * EFI/boot/bootx64.efi
 * EFI/boot/grub.cfg

Now copy the EFI folder and files to the root of the EFIBOOT USB.

3. Download the required Linux kernel and ramdisk and transfer to the USB.

MicroCore Linux 6.0 uses the following kernel and ramdisk file names:

 * boot/vmlinuz
 * boot/core.gz

The same file names are used in the Micron M550 SSD firmware update tool for
firmware MU02. This might change for new SSD models and firmware releases. 

4. Check the USB contents and edit the grub.cfg configuration file as needed.

The following files should now be found on our EFIBOOT USB:

 * EFI/boot/unicode.pf2
 * EFI/boot/bootx64.efi
 * EFI/boot/grub.cfg
 * boot/vmlinuz
 * boot/core,gz

5. Set the boot flag for the FAT32 partition (optional step).

This is an optional step and is not needed in most cases where an msdos
partition table is used. There might be some EFI/UEFI implementations where
this is needed.

In Linux we can use the Gparted application to change the partition flags.

6. Shutdown/reboot the computer.

When restarting a Mac, press and hold the Option key at boot time.
In a few seconds, Startup Manager appears and you can select the USB device.

For some UEFI based motherboards, you might need to press F9, F12 or another key
in order to select the correct boot device.

When the GRUB bootloader runs, the GRUB menu can be seen and the user can then
select the preferred boot option using the up/down arrow keys.

If no key is pressed, the default menu option is used.

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