The only target dependency for most hardware is sizeof(target_phys_addr_t).
Build these files into a convenience library, and use that instead of
building for every target.
Remove and poison various target specific macros to avoid bogus target
dependencies creeping back in.
Big/Little endian is not handled because devices should not know or care
about this to start with.
Signed-off-by: Paul Brook <paul@codesourcery.com>
Allow devices/drivers to register themselves via constructors.
Destructors are not needed (can be registered from a constructor)
and "priority" has been renamed and changed to an enum for clarity.
Signed-off-by: Paul Brook <paul@codesourcery.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
osdep.c is built in both as a toplevel target independant object, and
as a per-target object because of kqemu dependencies. Under some
circumstances make picks up the wrong one.
Build the former as tool-osdep to avoid this conflict.
Signed-off-by: Paul Brook <paul@codesourcery.com>
We already print a directory prefix in non-verbose mode, so there's no
point printing a messages when recursive make enters/leaves a directory.
Signed-off-by: Paul Brook <paul@codesourcery.com>
On ppc, cutils.o needs cache-utils.o or an undefined reference to
qemu_cache_conf results.
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
attached patch makes qemu use install consistently.
Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7177 c046a42c-6fe2-441c-8c8c-71466251a162
Automatically rerun configure when it is needed.
Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7110 c046a42c-6fe2-441c-8c8c-71466251a162
This patch adds a new qemu-io tool that links against the block layer and
image formats and allow to exercise them without needing a guest image.
It is inspired by the xfs_io tool which does the same for plain file I/O.
In fact the libxcmd library which is the backend of xfs_io is reused by this
tool in a limited fashing (cmd.[ch] files).
This version tests out most of the plain block I/O commands with the
most notable absent commands beeing snapshot handling and real aio.
This tool is the basis of the I/O path test suite I'm working on right now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6990 c046a42c-6fe2-441c-8c8c-71466251a162
Currently qemu unconditionally strips binaries on install. This
is a problem for packagers who may want to store/ship debug symbols
of compiled packages for debugging purposes.
Keep stripping as default for the oldtimers and add a
--disable-strip flag to override.
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6983 c046a42c-6fe2-441c-8c8c-71466251a162
Try to keep documentation about command line switches, -help text and
qemu_options table synchronized.
In true Qemu tradition, an include file is generated from single .hx file
containing all relevant information in one place. The include file is
parsed once for getting the enums, another time for getopt tables and
hird time for help messages. Texi documentation for the options is
generated from the same .hx file.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6884 c046a42c-6fe2-441c-8c8c-71466251a162
This patch introduces a generic internal API for access control lists
to be used by network servers in QEMU. It adds support for checking
these ACL in the VNC server, in two places. The first ACL is for the
SASL authentication mechanism, checking the SASL username. This ACL
is called 'vnc.username'. The second is for the TLS authentication
mechanism, when x509 client certificates are turned on, checking against
the Distinguished Name of the client. This ACL is called 'vnc.x509dname'
The internal API provides for an ACL with the following characteristics
- A unique name, eg vnc.username, and vnc.x509dname.
- A default policy, allow or deny
- An ordered series of match rules, with allow or deny policy
If none of the match rules apply, then the default policy is
used.
There is a monitor API to manipulate the ACLs, which I'll describe via
examples
(qemu) acl show vnc.username
policy: allow
(qemu) acl policy vnc.username denya
acl: policy set to 'deny'
(qemu) acl allow vnc.username fred
acl: added rule at position 1
(qemu) acl allow vnc.username bob
acl: added rule at position 2
(qemu) acl allow vnc.username joe 1
acl: added rule at position 1
(qemu) acl show vnc.username
policy: deny
0: allow fred
1: allow joe
2: allow bob
(qemu) acl show vnc.x509dname
policy: allow
(qemu) acl policy vnc.x509dname deny
acl: policy set to 'deny'
(qemu) acl allow vnc.x509dname C=GB,O=ACME,L=London,CN=*
acl: added rule at position 1
(qemu) acl allow vnc.x509dname C=GB,O=ACME,L=Boston,CN=bob
acl: added rule at position 2
(qemu) acl show vnc.x509dname
policy: deny
0: allow C=GB,O=ACME,L=London,CN=*
1: allow C=GB,O=ACME,L=Boston,CN=bob
By default the VNC server will not use any ACLs, allowing access to
the server if the user successfully authenticates. To enable use of
ACLs to restrict user access, the ',acl' flag should be given when
starting QEMU. The initial ACL activated will be a 'deny all' policy
and should be customized using monitor commands.
eg enable SASL auth and ACLs
qemu .... -vnc localhost:1,sasl,acl
The next patch will provide a way to load a pre-defined ACL when
starting up
Makefile | 6 +
b/acl.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
b/acl.h | 74 ++++++++++++++++++++++
configure | 18 +++++
monitor.c | 95 ++++++++++++++++++++++++++++
qemu-doc.texi | 49 ++++++++++++++
vnc-auth-sasl.c | 16 +++-
vnc-auth-sasl.h | 7 ++
vnc-tls.c | 19 +++++
vnc-tls.h | 3
vnc.c | 21 ++++++
vnc.h | 3
12 files changed, 491 insertions(+), 5 deletions(-)
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6726 c046a42c-6fe2-441c-8c8c-71466251a162
This patch adds the new SASL authentication protocol to the VNC server.
It is enabled by setting the 'sasl' flag when launching VNC. SASL can
optionally provide encryption via its SSF layer, if a suitable mechanism
is configured (eg, GSSAPI/Kerberos, or Digest-MD5). If an SSF layer is
not available, then it should be combined with the x509 VNC authentication
protocol which provides encryption.
eg, if using GSSAPI
qemu -vnc localhost:1,sasl
eg if using TLS/x509 for encryption
qemu -vnc localhost:1,sasl,tls,x509
By default the Cyrus SASL library will look for its configuration in
the file /etc/sasl2/qemu.conf. For non-root users, this can be overridden
by setting the SASL_CONF_PATH environment variable, eg to make it look in
$HOME/.sasl2. NB unprivileged users may not have access to the full range
of SASL mechanisms, since some of them require some administrative privileges
to configure. The patch includes an example SASL configuration file which
illustrates config for GSSAPI and Digest-MD5, though it should be noted that
the latter is not really considered secure any more.
Most of the SASL authentication code is located in a separate source file,
vnc-auth-sasl.c. The main vnc.c file only contains minimal integration
glue, specifically parsing of command line flags / setup, and calls to
start the SASL auth process, to do encoding/decoding for data.
There are several possible stacks for reading & writing of data, depending
on the combo of VNC authentication methods in use
- Clear. read/write straight to socket
- TLS. read/write via GNUTLS helpers
- SASL. encode/decode via SASL SSF layer, then read/write to socket
- SASL+TLS. encode/decode via SASL SSF layer, then read/write via GNUTLS
Hence, the vnc_client_read & vnc_client_write methods have been refactored
a little.
vnc_client_read: main entry point for reading, calls either
- vnc_client_read_plain reading, with no intermediate decoding
- vnc_client_read_sasl reading, with SASL SSF decoding
These two methods, then call vnc_client_read_buf(). This decides
whether to write to the socket directly or write via GNUTLS.
The situation is the same for writing data. More extensive comments
have been added in the code / patch. The vnc_client_read_sasl and
vnc_client_write_sasl method implementations live in the separate
vnc-auth-sasl.c file.
The state required for the SASL auth mechanism is kept in a separate
VncStateSASL struct, defined in vnc-auth-sasl.h and included in the
main VncState.
The configure script probes for SASL and automatically enables it
if found, unless --disable-vnc-sasl was given to override it.
Makefile | 7
Makefile.target | 5
b/qemu.sasl | 34 ++
b/vnc-auth-sasl.c | 626 ++++++++++++++++++++++++++++++++++++++++++++++++++++
b/vnc-auth-sasl.h | 67 +++++
configure | 34 ++
qemu-doc.texi | 97 ++++++++
vnc-auth-vencrypt.c | 12
vnc.c | 249 ++++++++++++++++++--
vnc.h | 31 ++
10 files changed, 1129 insertions(+), 33 deletions(-)
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6724 c046a42c-6fe2-441c-8c8c-71466251a162
This patch refactors the existing TLS code to make the main VNC code
more managable. The code moves to two new files
- vnc-tls.c: generic helpers for TLS handshake & credential setup
- vnc-auth-vencrypt.c: the actual VNC TLS authentication mechanism.
The reason for this split is that there are other TLS based auth
mechanisms which we may like to use in the future. These can all
share the same vnc-tls.c routines. In addition this will facilitate
anyone who may want to port the vnc-tls.c file to allow for choice
of GNUTLS & NSS for impl.
The TLS state is moved out of the VncState struct, and into a separate
VncStateTLS struct, defined in vnc-tls.h. This is then referenced from
the main VncState. End size of the struct is the same, but it keeps
things a little more managable.
The vnc.h file gains a bunch more function prototypes, for functions
in vnc.c that were previously static, but now need to be accessed
from the separate auth code files.
The only TLS related code still in the main vl.c is the command line
argument handling / setup, and the low level I/O routines calling
gnutls_send/recv.
Makefile | 11
b/vnc-auth-vencrypt.c | 167 ++++++++++++++
b/vnc-auth-vencrypt.h | 33 ++
b/vnc-tls.c | 414 +++++++++++++++++++++++++++++++++++
b/vnc-tls.h | 70 ++++++
vnc.c | 581 +++-----------------------------------------------
vnc.h | 76 ++++--
7 files changed, 780 insertions(+), 572 deletions(-)
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6723 c046a42c-6fe2-441c-8c8c-71466251a162
Each of the graphical frontends #include a .c file, for keymap code
resulting in duplicated definitions & duplicated compiled code. A
couple of small changes allowed this to be sanitized, so instead of
doing a #include "keymaps.c", duplicating all code, we can have a
shared keymaps.h file, and only compile code once. This allows the
next patch to move the VncState struct out into a header file without
causing clashing definitions.
Makefile | 9 +++++---
b/keymaps.h | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
curses.c | 3 --
curses_keys.h | 9 +++-----
keymaps.c | 45 ++++++++++++++++---------------------------
sdl.c | 3 --
sdl_keysym.h | 7 ++----
vnc.c | 5 +---
vnc_keysym.h | 7 ++----
9 files changed, 97 insertions(+), 51 deletions(-)
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6721 c046a42c-6fe2-441c-8c8c-71466251a162
Derived from Stuart Brady's patch: Show the target directory as prefix
to the current module when building in quiet mode. This helps to gain
overview of the current build progress, specifically when running
parallelized builds.
Furthermore, suppress make command echoing when entering subdirs and
replace $(subst subdir-,,$@) with $* in the related rule.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6447 c046a42c-6fe2-441c-8c8c-71466251a162
make install-doc omits an explicit permission mask for the man-pages. This
defaults to have the executable bits set. Adding "-m 644" (for rw-r--r--)
fixes that.
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6400 c046a42c-6fe2-441c-8c8c-71466251a162
Put archive utility (ar) invocations into a rule, and have it generate
quiet output by default.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6381 c046a42c-6fe2-441c-8c8c-71466251a162
Spew out less noise when compiling. This helps review make output for
information such as compilation warnings, rather than extra long compiler
invocations.
The full output can be generated by supplying a 'V=1' parameter to make.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6380 c046a42c-6fe2-441c-8c8c-71466251a162
Use generic rules where posssible, and a LINK macro where not.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6379 c046a42c-6fe2-441c-8c8c-71466251a162
Add a file for common makefile rules.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6378 c046a42c-6fe2-441c-8c8c-71466251a162
Instead of specifying the compilation command over and over, use a single
rule and adjust it as necessary using target specific target overrides.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6377 c046a42c-6fe2-441c-8c8c-71466251a162
This patch fixes the 'tarbin' Makefile rule (which was broken due to
a missing '\' for line-continuation), and also rearranges that rule to
match the ordering that is used in the configure script, so that the
list can be checked more easily, to avoid conflicts, etc.
Signed-off-by: Stuart Brady <stuart.brady@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6149 c046a42c-6fe2-441c-8c8c-71466251a162
Since most IO devices are integrated into the 440EP chip, "Bamboo support"
mostly entails implementing the -kernel, -initrd, and -append options.
These options are implemented by loading the guest as if u-boot had done it,
i.e. loading a flat device tree, updating it to hold initrd addresses, ram
size, and command line, and passing the FDT address in r3.
Since we use it with KVM, we enable the virtio block driver and include hooks
necessary for KVM support.
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6067 c046a42c-6fe2-441c-8c8c-71466251a162
glibc implements posix-aio as a thread pool and imposes a number of limitations.
1) it limits one request per-file descriptor. we hack around this by dup()'ing
file descriptors which is hideously ugly
2) it's impossible to add new interfaces and we need a vectored read/write
operation to properly support a zero-copy API.
What has been suggested to me by glibc folks, is to implement whatever new
interfaces we want and then it can eventually be proposed for standardization.
This requires that we implement our own posix-aio implementation though.
This patch implements posix-aio using pthreads. It immediately eliminates the
need for fd pooling.
It performs at least as well as the current posix-aio code (in some
circumstances, even better).
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5996 c046a42c-6fe2-441c-8c8c-71466251a162
This is pure code motion. The savevm code is all common code so we can build
it once and share the object with all executables.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5700 c046a42c-6fe2-441c-8c8c-71466251a162
This will improve the build time.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5699 c046a42c-6fe2-441c-8c8c-71466251a162
Replace signalfd with signal handler/pipe. There is no way to interrupt
the CPU execution loop when a file descriptor becomes readable. This
results in a large performance regression in sparc emulation during
bootup.
This patch switches us to signal handler/pipe which was originally
suggested by Ian Jackson. The signal handler lets us interrupt the
CPU emulation loop while the write to a pipe lets us avoid the
select/signal race condition.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5451 c046a42c-6fe2-441c-8c8c-71466251a162
This does the reverse of bt-host.c, proxying from guest to host.
Appears to be more reliable.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5348 c046a42c-6fe2-441c-8c8c-71466251a162
Note that the L2CAP flow-controlled mode is not fully supported.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5346 c046a42c-6fe2-441c-8c8c-71466251a162
This implements most of the logic of a real HCI (at least the pieces
marked as mandatory). It doesn't support keys, authentication etc.
It works on top of the LMP layer, which is not fully emulated because
software never has direct access to it.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5345 c046a42c-6fe2-441c-8c8c-71466251a162
This allows using a host's physical HCI as one of the HCIs attached
to the virtual machine. This brings various limitations because not
all commands/events are passed through by Linux kernel, some are
interpreted by the host's kernel for a speed gain.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5344 c046a42c-6fe2-441c-8c8c-71466251a162
This patch fixes some items in Makefile:
* remove duplicate entries from .PHONY
* add missing entries to .PHONY
* sort entries in .PHONY alphabetically
* add missing dependencies for qemu-doc.* targets
Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5307 c046a42c-6fe2-441c-8c8c-71466251a162
This patch refactors the AIO layer to allow multiple AIO implementations. It's
only possible because of the recent signalfd() patch.
Right now, the AIO infrastructure is pretty specific to the block raw backend.
For other block devices to implement AIO, the qemu_aio_wait function must
support registration. This patch introduces a new function,
qemu_aio_set_fd_handler, which can be used to register a file descriptor to be
called back. qemu_aio_wait() now polls a set of file descriptors registered
with this function until one becomes readable or writable.
This patch should allow the implementation of alternative AIO backends (via a
thread pool or linux-aio) and AIO backends in non-traditional block devices
(like NBD).
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5297 c046a42c-6fe2-441c-8c8c-71466251a162
Right now, we sprinkle #if defined(QEMU_IMG) && defined(QEMU_NBD) all over the
code. It's ugly and causes us to have to build multiple object files for
linking against qemu and the tools.
This patch introduces a new file, qemu-tool.c which contains enough for
qemu-img, qemu-nbd, and QEMU to all share the same objects.
This also required getting qemu-nbd to be a bit more Windows friendly. I also
changed the Windows block-raw to use normal IO instead of overlapping IO since
we don't actually do AIO yet on Windows. I changed the various #if 0's to
#if WIN32_AIO to make it easier for someone to eventually fix AIO on Windows.
After this patch, there are no longer any #ifdef's related to qemu-img and
qemu-nbd.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5226 c046a42c-6fe2-441c-8c8c-71466251a162
OpenBSD doesn't use AIO so don't try to build compatfd when not using AIO.
Also make sure to call qemu_aio_init() from bdrv_init. Everything that uses
bdrv calls bdrv_init so it makes sense to init aio from there instead of
in every single tool.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5197 c046a42c-6fe2-441c-8c8c-71466251a162
This patch introduces signalfd() to work around the signal/select race in
checking for AIO completions. For platforms that don't support signalfd(), we
emulate it with threads.
There was a long discussion about this approach. I don't believe there are any
fundamental problems with this approach and I believe eliminating the use of
signals is a good thing.
I've tested Windows and Linux using Windows and Linux guests. I've also checked
for disk IO performance regressions.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5187 c046a42c-6fe2-441c-8c8c-71466251a162
Right now, the Windows build is broken because of NBD. Using a mingw32 cross
compiler is also badly broken.
This patch fixes the Windows build by stubbing out NBD support until someone
fixes it for Windows. It also santizing the mingw32 cross compiler support
by replacing the --enable-mingw32 option with a compiler check to determine
if we're on windows or not.
Also remove the weird SDL pseudo-detection for mingw32 using a cross compiler.
The hardcoded sdl-config name is seemly arbitrary. If you cross compiler SDL
correctly and modify your PATH variable appropriately, it will Just Work when
cross compiling.
The audio driver detection is also broken for cross compiling so you have to
specify the audio drivers explicitly for now.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5046 c046a42c-6fe2-441c-8c8c-71466251a162
Compilation of QEMU is currently broken on Solaris due to nbd's use of _IO and
due to network libraries not being linked into qemu-img.
The attached patch adds the appropriate libraries (copied from Makefile.target)
and includes an additional Sun-specific header for _IO.
With these fixes it compiles okay, on OpenSolaris snv_93 (amd64).
Signed-off-by: Andreas Faerber <andreas.faerber@web.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4982 c046a42c-6fe2-441c-8c8c-71466251a162
Also add various peripherals: two miscellaneous Nokia CBUS chips,
EPSON S1D13745 LCD/TV remote-framebuffer controller,
TWL92230 - standard OMAP2 power management companion chip on i2c.
Generic OneNAND flash memory,
TMP105 temperature sensor on i2c.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4215 c046a42c-6fe2-441c-8c8c-71466251a162
Remove QEMU_TOOL. Replace with QEMU_IMG and NEED_CPU_H.
Avoid linking qemu-img against whole system emulatior.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3578 c046a42c-6fe2-441c-8c8c-71466251a162
