PPC uImage build not reporting correctly

[cpclark at xmission.com]

On Tue, 10 May 2005, Sam Ravnborg wrote:

> On Mon, May 09, 2005 at 10:19:01AM -0500, Kumar Gala wrote:
> > 
> > On May 6, 2005, at 6:22 PM, <cpclark at xmission.com> wrote:
> > 
> > >On Fri, 6 May 2005, Kumar Gala wrote:
> > > > I tried the following w/o success:
> > > >
> > > > $(obj)/uImage: $(obj)/vmlinux.gz
> > > >         $(Q)rm -f $@
> > > >         $(call if_changed,uimage)
> > > >         @echo ' Image: $@' $(shell if [ -f $@ ]; then echo 'is ready'; else echo 'not made'; fi)
> > >
> > >Couldn't you eliminate the ($shell ..) construct altogether, like this?:
> > >
> > >$(obj)/uImage: $(obj)/vmlinux.gz
> > >        $(Q)rm -f $@
> > >        $(call if_changed,uimage)
> > >        @echo -n '? Image: $@'
> > >        @if [ -f $@ ]; then echo 'is ready' ; else echo 'not made'; fi
> > 
> > Yes, and this seems to actually work.
> > 
> > Sam, does this look reasonable to you.  If so I will work up a patch.
>
> Looks ok - but I do not see why use of $(shell ...) did not work out.

As I understand it, the $(shell ...) construct doesn't "work" in the case 
cited above because make evaluates/expands the $(shell ...) stuff while it 
is parsing the makefile and building the command list--i.e. before it has 
issued any commands to build anything.  What seems to be desired in this 
case is a file-existence test which runs "inline" with respect to the 
preceding commands.  The use of $(shell ...) inside a command 
subverts/preempts that natural sequence.  I think. :-)

Chris