Re: [Xen-devel] [PATCH] tools: don't expand prefix and exec_prefix too early

[Matt Wilson <msw@xxxxxxxxxx>]

On Wed, Aug 08, 2012 at 07:26:35AM -0700, Jan Beulich wrote:
> A comment in tools/configure says that it is intended for these to be
> command line overridable, so they shouldn't get expanded at configure
> time.

I'm not sure which comment you're referencing, or which command line
it's intended that you're able to override prefix/exec_prefix. Could
you point it out? What's not working?

> The patch is fixing tools/m4/default_lib.m4 as far as I can see myself
> doing this, but imo it is flawed altogether and should rather be
> removed:
> - setting prefix and exec_prefix to default values is being done later
>   in tools/configure anyway
> - setting LIB_PATH based on the (non-)existence of a lib64 directory
>   underneath ${exec_prefix} is plain wrong (it can obviously exist on a
>   32-bit installation)
> - I wasn't able to locate any use of LIB_PATH

I believe that the LIB_PATH portions can now be removed. I also
believe you're right that all of this can be removed. Did you attempt
that as well?

> (I did see IanC's comment in c/s 25594:ad08cd8e7097 that removing it
> supposedly causes other problems, but I don't see how that would
> happen).

The tail of the thread where IanC had trouble is here: 
  http://lists.xen.org/archives/html/xen-devel/2012-07/msg00268.html

If we're going back into this code, I think that adding a lowercase
prefix variable and removing default_lib.m4 altogether should resolve
remaining problems. But we should probably only do that for 4.2 if
something's very broken with what's in the tree now.

> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> ---
> This will require tools/configure to be re-generated.

This is typically part of the same commit.

Matt

> --- a/config/Tools.mk.in
> +++ b/config/Tools.mk.in
> @@ -1,5 +1,6 @@
>  # Prefix and install folder
> -PREFIX              := @prefix@
> +prefix              := @prefix@
> +PREFIX              := $(prefix)
>  exec_prefix         := @exec_prefix@
>  LIBDIR              := @libdir@
>  
> --- a/tools/m4/default_lib.m4
> +++ b/tools/m4/default_lib.m4
> @@ -1,14 +1,19 @@
>  AC_DEFUN([AX_DEFAULT_LIB],
> -[AS_IF([test "\${exec_prefix}/lib" = "$libdir"],
> -    [AS_IF([test "$exec_prefix" = "NONE" && test "$prefix" != "NONE"],
> -        [exec_prefix=$prefix])
> -    AS_IF([test "$exec_prefix" = "NONE"], [exec_prefix=$ac_default_prefix])
> -    AS_IF([test -d "${exec_prefix}/lib64"], [
> +[AS_IF([test "\${exec_prefix}/lib" = "$libdir"], [
> +    AS_IF([test "$prefix" = "NONE"], [prefix=$ac_default_prefix])
> +    AS_IF([test "$exec_prefix" = "NONE"], [exec_prefix='${prefix}'])
> +    AS_IF([eval test -d "${exec_prefix}/lib64"], [
>          LIB_PATH="lib64"
>      ],[
>          LIB_PATH="lib"
>      ])
>  ], [
>      LIB_PATH="${libdir:`expr length "$exec_prefix" + 1`}"
> +    AS_IF([test -z "${libdir##\$\{exec_prefix\}/*}"], [
> +        LIB_PATH="${libdir:15}"
> +    ])
> +    AS_IF([test -z "${libdir##\$exec_prefix/*}"], [
> +        LIB_PATH="${libdir:13}"
> +    ])
>  ])
>  AC_SUBST(LIB_PATH)])
> 
> 
> 

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