Re: [PATCH] build/xen: fail to rebuild if Kconfig fails

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Fri, Feb 16, 2024 at 11:04:46AM +0100, Jan Beulich wrote:
> On 15.02.2024 18:23, Roger Pau Monné wrote:
> > On Thu, Feb 15, 2024 at 05:22:00PM +0100, Jan Beulich wrote:
> >> On 15.02.2024 17:08, Roger Pau Monné wrote:
> >>> On Thu, Feb 15, 2024 at 02:02:41PM +0100, Jan Beulich wrote:
> >>>> --- a/xen/Rules.mk
> >>>> +++ b/xen/Rules.mk
> >>>> @@ -15,7 +15,11 @@ srcdir := $(srctree)/$(src)
> >>>>  PHONY := __build
> >>>>  __build:
> >>>>  
> >>>> --include $(objtree)/include/config/auto.conf
> >>>> +ifneq ($(obj),tools)
> >>>> +ifneq ($(obj),tools/kconfig)
> >>>> +include $(objtree)/include/config/auto.conf
> >>>> +endif
> >>>> +endif
> >>>
> >>> Trying to understand this, I assume it's to avoid an infinite
> >>> dependency loop that generating include/config/auto.conf requires some
> >>> tools that are build using xen/Rules.mk?
> >>
> >> The file has dependencies only in xen/Makefile. This is about the
> >> file simply not being there when initially building. Perhaps the
> >> patch description helps that I've written in the meantime:
> >>
> >> "Because of using "-include", failure to (re)build auto.conf (with
> >>  auto.conf.cmd produced as a secondary target) won't stop make from
> >>  continuing the build. Arrange for it being possible to drop the - from
> >>  Rules.mk, requiring that the include be skipped for tools-only targets.
> > 
> > Wouldn't it be more reliable if we skipped the include for any paths
> > in $(obj) that start with 'tools', rather than hardcoding 'tools' and
> > 'tools/kconfig'?
> 
> I was first meaning to do so, but the expression would end up more
> complex than I'd like (for it needing to be an exact match of "tools"
> and a prefix match of "tools/"). Thinking of it,
> 
> ifneq ($(obj),tools)
> ifneq ($(patsubst tools/%,$(obj)),)
> 
> might do (and not be as complex as I first thought, when intending to
> put all in a single "if").

Would something like the rune below work?

ifneq ($(word 1, $(subst /, ,$(obj))),tools)

That should allow to have a single condition, and should match both
'tools' and 'tools/*'

Thanks, Roger.