1GPT fdisk (aka gdisk) and FixParts 2 3by Roderick W. Smith, rodsmith@rodsbooks.com 4 5******************************** IMPORTANT ******************************** 6Most versions of Windows cannot boot from a GPT disk on BIOS-based 7computers, and most varieties prior to Vista cannot read GPT disks. GPT 8fdisk is a partition editor for GPT disks, and it will *AUTOMATICALLY 9CONVERT* MBR disks to GPT form. Therefore, you should **NOT** use GPT fdisk 10on a Windows system unless you fully understand what you're doing or are 11certain that your computer boots in EFI/UEFI mode! If you accidentally use 12GPT fdisk on a BIOS-mode boot disk, or perhaps even on a data disk, you may 13find recovery to be very difficult! Pre-installed Windows 8 and later 14systems almost always use GPT disks and boot in EFI/UEFI mode, but 15self-installed Windows 8 systems sometimes use BIOS mode. This caveat does 16not apply to FixParts, though; that tool works only on MBR disks. 17*************************************************************************** 18 19Read the main README file for general information on the program, and read 20the gdisk.html or fixparts.html documents (the Linux man pages converted to 21HTML format) for detailed use information. My GPT fdisk Web page, 22http://www.rodsbooks.com/gdisk/, provides a more tutorial introduction to 23the software. I originally wrote GPT fdisk on Linux, and some Linux- and 24Unix-centric language remains in the documentation. 25 26Windows Use Notes 27----------------- 28 29The Windows version of GPT fdisk was added with version 0.6.2 of the 30package. The Windows binary package includes the gdisk.exe interactive 31text-mode program file but no equivalent to the sgdisk program that's 32available with Linux, FreeBSD, and OS X builds. In theory, an sgdisk.exe 33for Windows could be built if the popt library were installed. I've not 34attempted to do this myself, though. If you care to try, check 35http://gnuwin32.sourceforge.net/packages/popt.htm for information on popt 36for Windows. 37 38Beginning with version 0.8.10, I'm distributing both 32-bit and 64-bit 39binaries, which include the strings "32" or "64" in their names. The 32-bit 40binaries work fine on most versions of Windows, but some 64-bit 41installations of Windows 8 lack 32-bit support libraries and so may need 42the 64-bit binaries. 43 44The FixParts program (fixparts32.exe and fixparts64.exe) is new with GPT 45fdisk 0.7.0. As described in the main README file, this program fixes 46certain partition table problems that can be created by buggy partitioning 47software. Windows seems to be unfazed by most such problems, but I've not 48done an extensive survey of Windows partitioning tools on this score. 49 50To install the programs, copy the gdisk32.exe and fixparts32.exe (or 51gdisk64.exe and fixparts64.exe) program files to any directory on your 52path, such as C:\Windows. Alternatively, you can change to the program's 53directory or type its complete path whenever you use it. 54 55To use the programs, first launch a Command Prompt as the Administrator. To 56do this, locate the Command Prompt program icon, right-click it, and select 57"Run as Administrator." If you use a non-Administrator Command Prompt, you 58won't be able to edit hard disk partition tables, although you will be able 59to edit raw disk image files. 60 61The program requires a hard disk identifier as an option. You can specify 62this in either of two forms. The first way is as a number followed by a 63colon, as in: 64 65gdisk 0: 66 67Disks are numbered starting from 0, so the preceding command launches gdisk 68on the first disk. The second way to specify a disk device is via a 69harder-to-remember name: 70 71gdisk32 \\.\physicaldrive0 72 73This command is equivalent to the earlier one -- it edits the partition 74table on the first physical disk. Change the number at the end of the 75device name to change the disk edited. 76 77If you pass the "-l" option to gdisk.exe in addition to the disk 78identifier, the program displays the current partition table information 79and then exits. This use entails no risk to MBR disks, since the program 80never writes data back to the disk when used in this way. 81 82As noted above, editing the first disk with GPT fdisk is usually a Bad 83Idea. An exception would be if your system uses an Extensible Firmware 84Interface (EFI) and already boots from a GPT disk. It's safer to edit 85non-boot disks, which usually have numbers of 1 and above, but only if you 86run a version of Windows with GPT support. For more information on Windows' 87support of GPT, see Microsoft's Web page on the topic: 88 89http://www.microsoft.com/whdc/device/storage/GPT_FAQ.mspx 90 91The Windows binaries I've compiled do not support Unicode UTF-16LE GPT 92partition names. This feature was added to version 0.7.1 of the software 93for Linux, FreeBSD, and OS X, and with changes to some #ifndef lines in the 94source files, it can be compiled for Windows; however, it seems to do 95little good in Windows because of Command Prompt window and/or ICU library 96limitations. Thus, I've omitted this support in the interests of 97simplifying the binary distribution, since including it would mean 98distributing the ICU libraries. 99 100Source Code and Compilation Issues 101---------------------------------- 102 103I have successfully compiled GPT fdisk using three different Windows 104compilers: 105 106- MinGW (http://www.mingw.org), and in particular its Linux-hosted 107 cross-compiler -- Under Ubuntu Linux, the Makefile.mingw and 108 Makefile.mingw64 files enable compilation of the software via MinGW. 109 (Type "make -f Makefile.mingw" to compile 32-bit binaries, and "make -f 110 Makefile.mingw64" to compile 64-bit binaries.) If you try to compile 111 using another compiler or even using MinGW under Windows or another Linux 112 variety, you may need to adjust the Makefile.mingw options. 113 114- Microsoft Visual C++ 2008 Express 115 (http://www.microsoft.com/express/Windows/) -- This compiler requires a 116 third-party stdint.h file (I used the one from 117 http://msinttypes.googlecode.com/svn/trunk/stdint.h), but it otherwise 118 works fine. A project is easily created by adding all the *.h files and 119 all the *.cc files except diskio-unix.cc, sgdisk.cc, and whichever 120 program file you intend to NOT build (gdisk.cc or fixparts.cc). 121 122- Microsoft Visual C++ 2010 Express -- This compiler works much like the 123 2008 version, although I didn't need to add a third-party stdint.h file. 124 125The MinGW compiler produces much larger executables than do the MS 126compilers. The resulting binaries seem to work equally well, but my testing 127has been minimal. 128 129I've also attempted to compile the code with OpenWatcom 1.8, but this 130attempt failed, mostly because the compiler can't yet handle iostream 131output on standard C++ strings. OpenWatcom also seems to have incorrectly 132set the value of UINT32_MAX as if uint32_t values were 64-bit integers. 133This alone won't cause the compile to fail, but it would create bugs. 134 135If you modify GPT fdisk to get it to compile under another compiler, I 136welcome submission of patches. 137