UEFI GPT fdisk Code
UEFI GTP fdisk is a disk partitionning tool running under UEFI/BIOS
Status: Beta
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Bernard Burette
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UEFI GPT fdisk: aka gdisk.efi by Bub'soft.
Build of GPT fdisk for UEFI BIOS environments.
Version 0.5 november 2015.
Version <1 means it's pretty much beta software like GPT fdisk in fact.
First attempt by Bernard Burette <bernard at burette dot net> january 2014.
This is a build of GPT fdisk for UEFI. You should be able to register it as
a boot-program in the UEFI or run it from the UEFI Shell if you system has
one. Anyway this executable image should be copied to the EFI System
Partition (aka EFI SP or Partition type 0xEF) to be permanently available. You
also have the option of copying it to a USB storage and invoke the UEFI Shell
then navigate ("fs1:", "cd xx", etc.) to your key to run it from there.
Unlike the original GPT fdisk "gdisk", this program accepts no options in its
command line. When you run it, it prints a list of all detected hard disks
each with a name like EFI_HANDLE(<hex_number>) and if more than one is found
lets you choose which one you want to review/edit.
Also the commands to backup the partition table to disk (b option in main
menu) and to load the partition table from a backup file (l option in recovery
menu) do not work (yet). I need to write the code to read from and write to a
file in pure UEFI first.
Apart from that all functions should operate properly. Refer to GPT fdisk
manual for more information on how to use this program:
http://www.rodsbooks.com/gdisk/
To successfully build UEFI GPT fdisk, you will additional packages:
- GPT fdisk, the original code can be found at:
http://sourceforge.net/projects/gptfdisk/
GPT fdisk needs g++ and additional libraries as well: check it's README.
- GNU-EFI library, can be found at:
http://sourceforge.net/projects/gnu-efi/
Unpack the sources from GPT fdisk to a location you like, it will create a
subdirectory containing all its stuff. Then go inside this subdirectory (for
example ~/gptfdisk.1.0.0) and there unpack *this* package, it will create
a new subdirectory (for example ~/gptfdisk.1.0.0/uefi-0.5) where you will
actually build the UEFI version of GPT fdisk. You now need to unpack GNU-EFI
package in this build directory, it will once again create its own
subdirectory (for example ~/gptfdisk.1.0.0/uefi-0.5/gnu-efi-3.0.3).
Depending on the version of GTP fdisk you use you need to patch some files
or not (GPT fdisk author has incorporated my changes in version after 0.8.10).
If you use version 0.8.10 or lower of GPT fdisk, there is a small patch to be
applied to GPT fdisk sources, the "PATCH.sh" script was written for that. The
program won't compile if you don't apply the patch to file "gpt.cc" and it
won't display the partition sizes in IEEE values if you don't patch the file
"support.cc". Note that since these patches are now included in GPT fdisk main
branch, the patch script shell will be removed in future revisions.
Now your current directory should still be ~/gptfdisk.1.0.0/uefi-0.5, so
just enter "make" and voilà!
A few things to know:
- We use GNU-EFI version 3.0.3 but any version around 3.x and hopefully newer
versions should work as well, you must adjust the directory name in the
Makefile when needed.
- We link against "libstdc++" - which at least for Ubuntu *was* compiled with
option _GLIBCXX_USE_WCHAR_T - when we only use UTF-8: this adds a lot of
useless bloat to the program. But only a full rewrite of GPT fdisk in plain
C could alleviate this.
- No 32 bits stuff has been done (is it still necessary nowadays?) the GNU-EFI
library can be compiled in both 32 bits and 64 bits but this program
will at the very least miss the start-up code "start-ia32.S" and the
relocation management code "relocate-ia32.c", feel free to help me if you
think this is a necessity.
- We use a hand-made version of the standard "libc" because the linux one
embeds system calls to the kernel (we don't want them because EFI has
nothing to do with Linux kernel), this library is mostly built from bits
copied from "dietlibc" but since GNU libstdc++ also calls __newlocale() some
other bits were copied from "glibc" (version 2.18 at the time of this
writing). This private "libc" library is called "libmy.a" and is built in
the "libmy/" subdirectory.
- We build these library files using 2 bytes wchar_t because EFI is UTF-16,
still gdisk uses UTF-8 internally so it doesn't need any other UTF-xx and
our glue functions hand code conversions from UTF-8 to EFI UTF-16: this
might not work in all languages.
- As written before the UEFI functions don't include directory and file
management so the parts of GPT fdisk for backup to file and recovery from
file don't work at all (the open() function returns EINVAL and GPT fdisk
will display an error).
- No C++ exception is handled here. The stack unwinding is tricky to implement
and fortunately GPT fdisk does not use exceptions at all.
- For all the system calls from the standard libray we build EFI versions
of functions like write(), read() and so on, all these functions are in the
".c" source files in this "." directory, not in "libmy/" subdirectory.
- We have added a "dynamic_cast.c" module that doesn't check anything because
the code should be fully debugged for all use cases and using libstdc++
doesn't work the way it should (remember we don't do C++ exceptions here, so
throwing a "bad_cast" would crash the program with no explanation).
- In version 0.5 some libmy.a files have been updated to compile with version
5.x of GCC, as this is the version packaged with most recent Ubuntu 15.10
you need around 20 MiB of free disk space to build everything, the gdisk.efi
programm itself is a little more than 1 MiB since GCC 5.2.