GPT fdisk (aka gdisk) by Roderick W. Smith, rodsmith@rodsbooks.com ******************************** IMPORTANT ******************************** Most versions of Windows cannot boot from a GPT disk, and most varieties prior to Vista cannot read GPT disks. GPT fdisk is a partition editor for GPT disks, and it will *AUTOMATICALLY CONVERT* MBR disks to GPT form. Therefore, you should **NOT** use GPT fdisk on a Windows system unless you fully understand what you're doing! If you accidentally use GPT fdisk on your boot disk, or perhaps even on a data disk, you may find recovery to be very difficult! *************************************************************************** Read the main README file for general information on the program, and read the gdisk.html document (the Linux man page converted to HTML format) for detailed use information. My GPT fdisk Web page, http://www.rodsbooks.com/gdisk/, provides a more tutorial introduction to the software. I originally wrote GPT fdisk on Linux, and some Linux- and Unix-centric language remains in the documentation. Windows Use Notes ----------------- The Windows version of GPT fdisk was added with version 0.6.2 of the package. The Windows binary package includes the gdisk.exe interactive text-mode program file but no equivalent to the sgdisk program that's available with Linux, FreeBSD, and OS X builds. In theory, an sgdisk.exe for Windows could be built if the popt library were installed. I've not attempted to do this myself, though. If you care to try, check http://gnuwin32.sourceforge.net/packages/popt.htm for information on popt for Windows. To install the program, copy the gdisk.exe program file to any directory on your path, such as C:\Windows. Alternatively, you can change to the program's directory or type its complete path whenever you use it. To use the program, first launch a Command Prompt as the Administrator. To do this, locate the Command Prompt program icon, right-click it, and select "Run as Administrator." If you use a non-Administrator Command Prompt, you won't be able to edit hard disk partition tables, although you will be able to edit raw disk image files. The program requires a hard disk identifier as an option. You can specify this in either of two forms. The first way is as a number followed by a colon, as in: gdisk 0: Disks are numbered starting from 0, so the preceding command launches gdisk on the first disk. The second way to specify a disk device is via a harder-to-remember name: gdisk \\.\physicaldrive0 This command is equivalent to the earlier one -- it edits the partition table on the first physical disk. Change the number at the end of the device name to change the disk edited. If you pass the "-l" option in addition to the disk identifier, the program displays the current partition table information and then exits. This use entails no risk to MBR disks, since the program never writes data back to the disk when used in this way. As noted above, editing the first disk with GPT fdisk is usually a Bad Idea. An exception would be if your system uses an Extensible Firmware Interface (EFI) and already boots from a GPT disk. It's safer to edit non-boot disks, which usually have numbers of 1 and above, but only if you run a version of Windows with GPT support. For more information on Windows' support of GPT, see Microsoft's Web page on the topic: http://www.microsoft.com/whdc/device/storage/GPT_FAQ.mspx The GUIDs generated by the program to uniquely identify disks and partitions aren't "proper" GUIDs; they're purely random numbers. In practice, this has caused me no problems; however, it's conceivable that some disk utility will complain. The Unix versions of GPT fdisk generate proper GUIDs, as of version 0.6.3. Note that this limitation applies ONLY to the unique GUIDs for disks and partitions, not to the GUIDs used to identify partition type codes; those are standardized and are handled correctly by all versions of GPT fdisk. Source Code and Compilation Issues ---------------------------------- I have successfully compiled GPT fdisk using two different Windows compilers: - MinGW (http://www.mingw.org), and in particular its Linux-hosted cross-compiler -- Under Fedora Linux, the Makefile.mingw file enables compilation of the software via MinGW. (Type "make -f Makefile.mingw" to compile the software.) If you try to compile using another compiler or even using MinGW under Windows or another Linux variety, you may need to adjust the Makefile.mingw options. - Microsoft Visual C++ 2008 Express (http://www.microsoft.com/express/Windows/) -- This compiler requires a third-party stdint.h file (I used the one from http://msinttypes.googlecode.com/svn/trunk/stdint.h), but it otherwise works fine. A project is easily created by adding all the *.h files and all the *.cc files except diskio-unix.cc and sgdisk.cc. The MinGW compiler produces much larger executables than does the MS compiler. The resulting binaries seem to work equally well, but my testing has been minimal. I've also attempted to compile the code with OpenWatcom 1.8, but this attempt failed, mostly because the compiler can't yet handle iostream output on standard C++ strings. OpenWatcom also seems to have incorrectly set the value of UINT32_MAX as if uint32_t values were 64-bit integers. This alone won't cause the compile to fail, but it would create bugs. If you modify GPT fdisk to get it to compile under another compiler, I welcome submission of patches.