Re: [PATCH v20210111 05/39] tools: add with-xen-scriptdir configure option

[Olaf Hering <olaf@xxxxxxxxx>]

Am Mon, 8 Feb 2021 16:03:29 +0000
schrieb Ian Jackson <iwj@xxxxxxxxxxxxxx>:

> I suggest this commit message as a compromise:
> 
>   Some distros plan for fresh installations will have an empty /etc,
>   whose content will not be controlled by the package manager
>   anymore.
> 
>   To make this possible, add a knob to configure to allow storing the
>   hotplug scripts to libexec instead of /etc/xen/scripts.
> 
> Olaf, would that be OK with you ?

Yes, this is fine. Thanks.


> As for detailed review:
> 
> > diff --git a/m4/paths.m4 b/m4/paths.m4
> > index 89d3bb8312..0cec2bb190 100644
> > --- a/m4/paths.m4
> > +++ b/m4/paths.m4  
> ...
> > +AC_ARG_WITH([xen-scriptdir],
> > +    AS_HELP_STRING([--with-xen-scriptdir=DIR],
> > +    [Path to directory for dom0 hotplug scripts. 
> > [SYSCONFDIR/xen/scripts]]),
> > +    [xen_scriptdir_path=$withval],
> > +    [xen_scriptdir_path=$sysconfdir/xen/scripts])  
> ...
> > -XEN_SCRIPT_DIR=$XEN_CONFIG_DIR/scripts
> > +XEN_SCRIPT_DIR=$xen_scriptdir_path
> >  AC_SUBST(XEN_SCRIPT_DIR)  
> 
> It is not clear to me why the deefault is changed from
> "$XEN_CONFIG_DIR/scripts" to "$sysconfdir/xen/scripts" and there isn't
> any explanation for this in the commit message.  I think this may make
> no difference but an explanation is called for.

The reason is the ordering of assignments in the file:
AC_ARG_WITH comes early in the file, XEN_CONFIG_DIR= is assigned much later.

It seems the assignments for CONFIG_DIR and XEN_CONFIG_DIR can be moved up, 
because $sysconfdir is expected to be set already. As a result the new 
AC_ARG_WITH= can continue to use "$XEN_CONFIG_DIR/scripts" for the default 
case. I assume the current ordering is to have a separate AC_ARG_WITH and 
AC_SUBST section.

Olaf

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