137 lines
6.9 KiB
Plaintext
137 lines
6.9 KiB
Plaintext
GPT fdisk (aka gdisk) and FixParts
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by Roderick W. Smith, rodsmith@rodsbooks.com
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******************************** IMPORTANT ********************************
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Most versions of Windows cannot boot from a GPT disk on BIOS-based
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computers, and most varieties prior to Vista cannot read GPT disks. GPT
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fdisk is a partition editor for GPT disks, and it will *AUTOMATICALLY
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CONVERT* MBR disks to GPT form. Therefore, you should **NOT** use GPT fdisk
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on a Windows system unless you fully understand what you're doing or are
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certain that your computer boots in EFI/UEFI mode! If you accidentally use
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GPT fdisk on a BIOS-mode boot disk, or perhaps even on a data disk, you may
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find recovery to be very difficult! Pre-installed Windows 8 and later
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systems almost always use GPT disks and boot in EFI/UEFI mode, but
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self-installed Windows 8 systems sometimes use BIOS mode. This caveat does
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not apply to FixParts, though; that tool works only on MBR disks.
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***************************************************************************
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Read the main README file for general information on the program, and read
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the gdisk.html or fixparts.html documents (the Linux man pages converted to
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HTML format) for detailed use information. My GPT fdisk Web page,
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http://www.rodsbooks.com/gdisk/, provides a more tutorial introduction to
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the software. I originally wrote GPT fdisk on Linux, and some Linux- and
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Unix-centric language remains in the documentation.
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Windows Use Notes
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-----------------
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The Windows version of GPT fdisk was added with version 0.6.2 of the
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package. The Windows binary package includes the gdisk.exe interactive
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text-mode program file but no equivalent to the sgdisk program that's
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available with Linux, FreeBSD, and OS X builds. In theory, an sgdisk.exe
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for Windows could be built if the popt library were installed. I've not
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attempted to do this myself, though. If you care to try, check
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http://gnuwin32.sourceforge.net/packages/popt.htm for information on popt
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for Windows.
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Beginning with version 0.8.10, I'm distributing both 32-bit and 64-bit
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binaries, which include the strings "32" or "64" in their names. The 32-bit
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binaries work fine on most versions of Windows, but some 64-bit
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installations of Windows 8 lack 32-bit support libraries and so may need
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the 64-bit binaries.
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The FixParts program (fixparts32.exe and fixparts64.exe) is new with GPT
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fdisk 0.7.0. As described in the main README file, this program fixes
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certain partition table problems that can be created by buggy partitioning
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software. Windows seems to be unfazed by most such problems, but I've not
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done an extensive survey of Windows partitioning tools on this score.
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To install the programs, copy the gdisk32.exe and fixparts32.exe (or
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gdisk64.exe and fixparts64.exe) program files to any directory on your
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path, such as C:\Windows. Alternatively, you can change to the program's
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directory or type its complete path whenever you use it.
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To use the programs, first launch a Command Prompt as the Administrator. To
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do this, locate the Command Prompt program icon, right-click it, and select
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"Run as Administrator." If you use a non-Administrator Command Prompt, you
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won't be able to edit hard disk partition tables, although you will be able
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to edit raw disk image files.
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The program requires a hard disk identifier as an option. You can specify
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this in either of two forms. The first way is as a number followed by a
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colon, as in:
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gdisk 0:
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Disks are numbered starting from 0, so the preceding command launches gdisk
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on the first disk. The second way to specify a disk device is via a
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harder-to-remember name:
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gdisk32 \\.\physicaldrive0
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This command is equivalent to the earlier one -- it edits the partition
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table on the first physical disk. Change the number at the end of the
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device name to change the disk edited.
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If you pass the "-l" option to gdisk.exe in addition to the disk
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identifier, the program displays the current partition table information
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and then exits. This use entails no risk to MBR disks, since the program
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never writes data back to the disk when used in this way.
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As noted above, editing the first disk with GPT fdisk is usually a Bad
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Idea. An exception would be if your system uses an Extensible Firmware
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Interface (EFI) and already boots from a GPT disk. It's safer to edit
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non-boot disks, which usually have numbers of 1 and above, but only if you
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run a version of Windows with GPT support. For more information on Windows'
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support of GPT, see Microsoft's Web page on the topic:
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http://www.microsoft.com/whdc/device/storage/GPT_FAQ.mspx
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The Windows binaries I've compiled do not support Unicode UTF-16LE GPT
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partition names. This feature was added to version 0.7.1 of the software
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for Linux, FreeBSD, and OS X, and with changes to some #ifndef lines in the
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source files, it can be compiled for Windows; however, it seems to do
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little good in Windows because of Command Prompt window and/or ICU library
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limitations. Thus, I've omitted this support in the interests of
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simplifying the binary distribution, since including it would mean
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distributing the ICU libraries.
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Source Code and Compilation Issues
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----------------------------------
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I have successfully compiled GPT fdisk using three different Windows
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compilers:
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- MinGW (http://www.mingw.org), and in particular its Linux-hosted
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cross-compiler -- Under Ubuntu Linux, the Makefile.mingw and
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Makefile.mingw64 files enable compilation of the software via MinGW.
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(Type "make -f Makefile.mingw" to compile 32-bit binaries, and "make -f
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Makefile.mingw64" to compile 64-bit binaries.) If you try to compile
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using another compiler or even using MinGW under Windows or another Linux
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variety, you may need to adjust the Makefile.mingw options.
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- Microsoft Visual C++ 2008 Express
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(http://www.microsoft.com/express/Windows/) -- This compiler requires a
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third-party stdint.h file (I used the one from
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http://msinttypes.googlecode.com/svn/trunk/stdint.h), but it otherwise
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works fine. A project is easily created by adding all the *.h files and
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all the *.cc files except diskio-unix.cc, sgdisk.cc, and whichever
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program file you intend to NOT build (gdisk.cc or fixparts.cc).
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- Microsoft Visual C++ 2010 Express -- This compiler works much like the
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2008 version, although I didn't need to add a third-party stdint.h file.
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The MinGW compiler produces much larger executables than do the MS
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compilers. The resulting binaries seem to work equally well, but my testing
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has been minimal.
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I've also attempted to compile the code with OpenWatcom 1.8, but this
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attempt failed, mostly because the compiler can't yet handle iostream
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output on standard C++ strings. OpenWatcom also seems to have incorrectly
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set the value of UINT32_MAX as if uint32_t values were 64-bit integers.
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This alone won't cause the compile to fail, but it would create bugs.
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If you modify GPT fdisk to get it to compile under another compiler, I
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welcome submission of patches.
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