Re: [Qemu-devel] [PATCH] configure: make it possible to disable IASL

[Marcel Apfelbaum <marcel.a@redhat.com>]

On Mon, 2013-11-25 at 13:26 +0200, Michael S. Tsirkin wrote:
> On Sun, Nov 24, 2013 at 09:58:34PM +0100, Stefan Weil wrote:
> > Am 24.11.2013 17:48, schrieb Michael S. Tsirkin:
> > > On Sun, Nov 24, 2013 at 05:39:58PM +0200, Michael S. Tsirkin wrote:
> > >> On Sun, Nov 24, 2013 at 02:54:51PM +0100, Stefan Weil wrote:
> > >>> Am 24.11.2013 14:42, schrieb Michael S. Tsirkin:
> > >>>> On Sun, Nov 24, 2013 at 03:04:04PM +0200, Marcel Apfelbaum wrote:
> > >>>>> On Sun, 2013-11-24 at 11:52 +0200, Michael S. Tsirkin wrote:
> > >>>>>> Useful for platforms with a broken IASL.
> > >>>>>>
> > >>>>>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > >>>>>> ---
> > >>>>>>  configure | 3 ++-
> > >>>>>>  1 file changed, 2 insertions(+), 1 deletion(-)
> > >>>>>>
> > >>>>>> diff --git a/configure b/configure
> > >>>>>> index 0592ba7..d0a0abe 100755
> > >>>>>> --- a/configure
> > >>>>>> +++ b/configure
> > >>>>>> @@ -1080,6 +1080,7 @@ echo "  --source-path=PATH       path of source code [$source_path]"
> > >>>>>>  echo "  --cross-prefix=PREFIX    use PREFIX for compile tools [$cross_prefix]"
> > >>>>>>  echo "  --cc=CC                  use C compiler CC [$cc]"
> > >>>>>>  echo "  --iasl=IASL              use ACPI compiler IASL [$iasl]"
> > >>>>>> +echo "                           iasl='' (empty string) disables ACPI compiler"
> > >>>>>>  echo "  --host-cc=CC             use C compiler CC [$host_cc] for code run at"
> > >>>>>>  echo "                           build time"
> > >>>>>>  echo "  --cxx=CXX                use C++ compiler CXX [$cxx]"
> > >>>>>> @@ -4269,7 +4270,7 @@ else
> > >>>>>>  fi
> > >>>>>>  echo "PYTHON=$python" >> $config_host_mak
> > >>>>>>  echo "CC=$cc" >> $config_host_mak
> > >>>>>> -if $iasl -h > /dev/null 2>&1; then
> > >>>>>> +if test "$iasl" && $iasl -h > /dev/null 2>&1; then
> > >>>>>>    echo "IASL=$iasl" >> $config_host_mak
> > >>>>>>  fi
> > >>>>>>  echo "CC_I386=$cc_i386" >> $config_host_mak
> > >>>>> I tried to disable iasl without this patch and it worked for me...
> > >>>>> I used:
> > >>>>>     - [Qemu-devel] [PATCH] configure: make --iasl option actually work
> > >>>>>     - ./configure --iasl="" (or --iasl=)
> > >>>>> and it worked (no sign of IASL in config-host.mak)
> > >>>>>
> > >>>>> I think this is because the prev test "$iasl -h > /dev/null 2>&1"
> > >>>>> fails of course.
> > >>>> By luck, yes.
> > >>>>
> > >>>> So this is just a documentation patch: cleaner to document the
> > >>>> interface explicitly.
> > >>>> I'll make this clearer in the commit log.
> > >>>>
> > >>> --iasl=false works without further modifications (because test "false
> > >>> -h" works and returns false). It also looks more natural than --iasl=.
> > >>>
> > >>> Cheers, Stefan
> > >> It seems that some people try --iasl= as the more natural way
> > >> to do this. It's not documented that a failing iasl will
> > >> cause a fall-back and I'd rather document an explicit option
> > >> than making it fail.
> > > I'm also curious why would you say =false is natural:
> > > it's a string option not a boolean one.
> > >
> > 
> > 'false' is a string here, namely the name of the executable which is
> > normally found at /bin/false.
> > It takes any number of parameters and always returns 1 (which is boolean
> > false
> > in shell conventions).
> > 
> > You could also write --iasl=/bin/false.
> > 
> > I suggest this kind of patch:
> > 
> >  echo "  --iasl=IASL              use ACPI compiler IASL [$iasl]"
> > +echo "                           iasl=false disables the ACPI compiler"
> 
> It's still not a natural interface.
> 
> It works by chance because we run iasl and test the return code,
> but we don't have to.
> For example, a reasonable implementation might produce
> an error if the user-specified iasl fails, breaking this hack.
> 
> Interfaces should not follow implementation.
> If you don't want iasl a reasonable syntax is '' or
> --disable-iasl.
+1 on --disable-iasl

Marcel

> >  echo "  --host-cc=CC             use C compiler CC [$host_cc] for code run at"
> > 
> > 
> > Stefan