Re: [Xen-devel] [VTPM v6 6/8] Add autoconf to stubdom

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-12-05 at 16:43 +0000, Fioravante, Matthew E. wrote:
> So the consensus is that the vtpm components are optional? I'm not
> sure I like basing the decision to build vtpm or not on the presence
> of cmake. That can lead to plenty of subtle surprises and hard to find
> build bugs for people building the same version of xen on different
> machines which may or may not have cmake installed.

This happens with lots of things when autoconf is involved, its
expected. (I mean in general not just in Xen).

If you don't want to be surprised you should add --enable-vtpm or
--disable-vtpm as appropriate.

>  I'd prefer to either enable or disable it by default and just keep
> the cmake check conditional on whether vtpm is enabled or not.
> 
> If we want vtpm (and its cmake dependency) to be optional, I can just
> make it default disabled. What do you all want? Default enabled or
> disabled?

Default to building if it can be built please.

Ian.

> 
> ________________________________________
> From: Ian Campbell [Ian.Campbell@xxxxxxxxxx]
> Sent: Wednesday, December 05, 2012 9:50 AM
> To: Fioravante, Matthew E.
> Cc: xen-devel@xxxxxxxxxxxxx; Ian Jackson
> Subject: Re: [Xen-devel] [VTPM v6 6/8] Add autoconf to stubdom
> 
> On Wed, 2012-12-05 at 14:32 +0000, Fioravante, Matthew E. wrote:
> > AC_ARG_VAR just allows you to do CMAKE=foo ./configure. It also adds a
> > message about the CMAKE variable when you do ./configure --help. I'm
> > not convinced this half needs to be conditional.
> 
> Agreed.
> 
> > The line that does the conditional check is the following:
> > AX_PATH_PROG_OR_FAIL_ARG([vtpm], [CMAKE], [cmake])
> >
> > AX_PATH_PROG_OR_FAIL_ARG is a new macro I added to path_or_fail.m4. It
> > does the same thing as AX_PATH_PROG_OR_FAIL if the first argument (in
> > this case "$vtpm") is equal to "y". If the argument is anything else
> > it sets the variable (in this case CMAKE) to
> > NAME_disabled_in_configure_script.
> 
> I see.
> 
> What I was expecting is that the default would be to build the vtpm
> stuff if cmake was installed and to silently not do so if cmake wasn't.
> If --enable-vtpm is given then it should of course fail noisily if cmake
> isn't present.
> 
> > The result is that if someone tries to build vtpm after disabling it
> > they will get a rather loud and obvious error message
> > cmake-disabled-in-configure-script: command not found.
> 
> That sounds fine too.
> 
> 



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