-libguestfs is a library for accessing and modifying guest disk images.
+Libguestfs is a library for accessing and modifying guest disk images.
Amongst the things this is good for: making batch configuration
changes to guests, getting disk used/free statistics (see also:
virt-df), migrating between virtualization systems (see also:
clones, cloning guests and changing registry/UUID/hostname info, and
much else besides.
-libguestfs uses Linux kernel and qemu code, and can access any type of
+Libguestfs uses Linux kernel and qemu code, and can access any type of
guest filesystem that Linux and qemu can, including but not limited
to: ext2/3/4, btrfs, FAT and NTFS, LVM, many different disk partition
schemes, qcow, qcow2, vmdk.
-libguestfs provides ways to enumerate guest storage (eg. partitions,
+Libguestfs provides ways to enumerate guest storage (eg. partitions,
LVs, what filesystem is in each LV, etc.). It can also run commands
in the context of the guest. Also you can mount guest filesystems on
the host (requires root privs and NFS).
-libguestfs is a library that can be linked with C and C++ management
+Libguestfs is a library that can be linked with C and C++ management
programs (or management programs written in other languages, if people
contribute the language bindings). You can also use it from shell
scripts or the command line.
-libguestfs was written by Richard W.M. Jones (rjones@redhat.com).
+Libguestfs was written by Richard W.M. Jones (rjones@redhat.com).
For discussion please use the fedora-virt mailing list:
https://www.redhat.com/mailman/listinfo/fedora-virt
Requirements
----------------------------------------------------------------------
-- nfs-utils source, unpacked
- http://download.sourceforge.net/nfs
+- recent QEMU with vmchannel support
-- Recent QEMU with vmchannel support
-
-- Compiled Linux kernels for 32 and/or 64 bit (see note below).
-
-- mkinitrd
-
-- cpio
+- febootstrap >= 1.2
- XDR, rpcgen
-- If you are running a 64 bit or non-x86 machine, see note below.
-
-We don't support initramfs at the moment. Patches gratefully
-received.
+- (Optional) local Fedora mirror
Running ./configure will check you have all the requirements installed
on your machine.
Building
----------------------------------------------------------------------
-Unpack nfs-utils source into a directory somewhere, then create a
-symlink daemon/nfs-utils to where you unpacked it. For example:
-
- pushd daemon
- tar zxf /path/to/nfs-utils-1.1.4.tar.gz
- ln -s nfs-utils-1.1.4 nfs-utils
- popd
-
-For nfs-utils 1.1.4, you may find that the patch
-(nfs-utils-1.1.4-build.patch) helps.
-
-Then make the library and shell tools:
+Then make the daemon, library and root filesystem:
- ./configure
+ ./configure [--with-mirror=URI]
make
-Make the daemon and NFS server:
- mkdir daemon/build
- pushd daemon/build
- ../configure [--disable-nfsv4 --disable-gss]
- make
- popd
-
-For 64 bit you'll probably want to build the 32 bit daemon and NFS
-server too:
-
- mkdir daemon/build-32
- pushd daemon/build-32
- ../configure --enable-32bit [--disable-nfsv4 --disable-gss]
- make
- popd
-
-For complex cross-architecture environments, you may want to build
-other versions of the daemon and NFS server as well. See the note
-below.
+Use the optional --with-mirror parameter to specify the URI of a local
+Fedora mirror. See the discussion of the MIRROR parameter in the
+febootstrap(8) manpage.
Finally run the tests:
make install
- pushd daemon/build
- make install
- popd
- # Repeat for each daemon/build* directory you made above.
-
-Note on 64 bit and non-x86 architectures
+Notes on cross-architecture support
----------------------------------------------------------------------
-The library runs the Linux kernel code in QEMU. It also runs a small
-control daemon inside QEMU. It might also run an NFS server. It
-might also run programs from the guest's disk/environment (if asked to).
-
-This leaves open the question of which QEMU do we run, eg. qemu (the
-i386 emulator) or qemu-system-x86_64 or qemu-system-ppc64 or ...?
-
-Several factors influence the choice:
-
-(a) The host architecture.
-
-(b) The guest architecture.
-
-(c) What kernel(s) we find at runtime.
+At the moment we basically don't support cross-architecture or
+32-on-64. This limits what is possible for some guests. Filesystem
+operations and NFS export will work fine, but running commands in
+guests may not be possible.
-(d) What compiler(s) we find at configure time.
+To enable this requires work for cross-architecture and 32-on-64
+support in febootstrap, fakeroot and fakechroot.
-(e) In general, we would prefer to run a 32 bit kernel over a 64 bit
-kernel, because that reduces the amount of system memory we have to
-give to qemu significantly, and makes libguestfs smaller, faster and
-use less memory.
+The daemon/ directory contains its own configure script. This is so
+that in future we will be able to cross-compile the daemon.
-For example, if (a) the host is x86-64, then it might be running a
-mixture of (b) i386 and x86-64 guests. Disk formats are stable, even
-across 32 and 64 bit and endianness changes, so it doesn't really
-matter what kernel we use if we just want to access files in the
-guest. In the absence of any other factors, we would choose an i386
-kernel and run it in plain 'qemu', because that would use the least
-amount of memory.
-But if we wanted to enable the feature of running a guest program in
-an x86-64 guest, then we have to run an x86-64 kernel and
-qemu-system-x86_64 (an i386 kernel can't run 64 bit programs). The
-same applies if we didn't find a 32 bit kernel at runtime, or if we
-couldn't run "gcc -m32" at configure time (because we can't compile
-the daemon).
-
-SO: to enable maximum features on 64 bit architectures:
-
-(1) Ensure that "gcc -m32" can create usable binaries.
-
-(2) Provide 32 and 64 bit kernels binaries at runtime.
-
-If you have a really weird environment, eg. you want to run programs
-inside PPC64 guests on your MIPS machine, then:
+Mirroring tip
+----------------------------------------------------------------------
-(3) Provide gcc cross-compiler and glibc for each architecture, and
-cross-compile the daemon and NFS server:
+Having a local Fedora mirror makes a massive difference to the time it
+takes to build and rebuild initramfs images.
- mkdir daemon/build-ppc64
- pushd daemon/build-ppc64
- ../configure --host=ppc64-gnu-linux
- make
- popd
+Failing that, use squid to cache yum downloads, but read this first:
+https://lists.dulug.duke.edu/pipermail/yum/2006-August/009041.html
+(In brief, because yum chooses random mirrors each time, squid doesn't
+work very well with default yum configuration. To get around this,
+choose a Fedora mirror which is close to you, set this with
+'./configure --with-mirror=[...]', and then proxy the whole lot
+through squid by setting http_proxy environment variable).
Copyright and license information
git.annexia.org / libguestfs.git / blobdiff