[Pkg-xen-devel] [patch] Activate Qemu options

[Ian Campbell]

On Thu, 2011-09-01 at 15:29 +0800, Thomas Goirand wrote:
> On 08/30/2011 06:49 PM, Ian Campbell wrote:
> > On Mon, 2011-08-29 at 17:51 +0800, Thomas Goirand wrote:
> >> Hi,
> >>
> >> This patch makes it possible for Qemu to use the SDL library, to
> >> conveniently replace VNC, which has horrible mouse support.
> >>
> >> It also adds a IOEMU_CONFIGURE_OPTIONS option in tools/Makefile, so that
> >> later on, we can call:
> >>
> >> $(MAKE_CLEAN) -C $(DIR)/tools $(CONFIG)
> >> IOEMU_CONFIGURE_OPTIONS="--audio-drv-list=\"pa oss alsa sdl esd\"
> >> --audio-card-list=\"ac97 es1370 sb16 cs4231a adlib gus\" --enable-mixemu"
> >>
> >> from debian/rules.real
> > 
> > That's quite an extensive list of audio devices. Where did it come from?
> > Do we really need to be emulating adlib and gus for example? Are people
> > really virtualising OSes of that era with the expectation that audio
> > will work/be useful?
> > 
> > The default list appears to be "ac97 es1370 sb16" which seems much more
> > reasonable. Remember that each additional device-model adds to the
> > security attack surface which is of particular interest for ones which
> > are not commonly used by the rest of the qemu universe.
> > 
> > In practical terms do you activate these using the dm_extra_args stuff
> > or something else?
> 
> No, you do an export of some variable so that qemu knows about what you
> want. I'll disable adlib and gus if you think it's a security issue, but
> I believe it's a shame to have options and not use them. It'd be quite
> nice to use Xen for example, to emulate old DOS machines, play old
> games, or old demos...

sb16 emulation ought to be sufficient to cover those uses cases I think?

In any case I'd have though dosbox would be a better tool for that
particular job.

> 
> > --- xen-4.1.1.orig/qemu/audio/sdlaudio.c
> > +++ xen-4.1.1/qemu/audio/sdlaudio.c
> > 
> > Is that the correct path, shouldn't this be a patch of a patch in
> > debian/patches or something?
> > 
> > 
> >> @@ -21,8 +21,8 @@
> >>   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> >>   * THE SOFTWARE.
> >>   */
> >> -#include <SDL.h>
> >> -#include <SDL_thread.h>
> >> +#include <SDL/SDL.h>
> >> +#include <SDL/SDL_thread.h>
> >>  #include "qemu-common.h"
> >> [...]
> >> @@ -67,6 +67,8 @@ CFLAGS += -DCONFIG_PASSTHROUGH
> >>  $(info === PCI passthrough capability has been enabled ===)
> >>  endif
> >>  
> >> +LIBS += -lpulse -lSDL
> >> +
> > 
> > These all seem a bit suspicious to me. Qemu's configure script contains
> > runes which call sdl_config to obtain correct CFLAGS and LIBS entries
> > for the library as well as code to detect a suitable version of sdl etc.
> > Is --enable-sdl not sufficient?
> > 
> > Ian.
> 
> Unless I'm mistaking, there's no such option such as --enable-sdl.

So there isn't, just --disable-sdl.

However the configure file seems to default to auto detecting sdl and
enables it if the required libraries etc are present. AFAICT simply
having the libsdl-dev package in the build-depends should be sufficient
to enable sdl support. I've just confirmed that installing libsdl-dev on
my Debian machines causes qemu to DTRT and enable SDL.

> When doing:
> /usr/src/xen/new/xen-4.1.1/debian/build/build-utils_i386/tools/../qemu/xen-setup
>  --audio-drv-list="pa oss alsa sdl esd" --audio-card-list="ac97 es1370
> sb16" --enable-mixemu --enable-sdl
> 
> then it tells:
> ERROR: unknown option --enable-sdl
> 
> Any pointer, or do you now agree with what I did?
> 
> Thomas
> 

-- 
Ian Campbell
Current Noise: Mulch - The Ancient

There is a 20% chance of tomorrow.