Re: [Xen-devel] [PATCH RFC] tools/xenlight: Create xenlight Makefile

[George Dunlap <dunlapg@xxxxxxxxx>]

On Fri, Dec 16, 2016 at 7:20 AM, Ronald Rojas <ronladred@xxxxxxxxx> wrote:
> Create a basic Makefile to build and install libxenlight Golang
> bindings.  Also add a template.

What's this template again?

>
> ---
>
> Eventually this patch will contain the actual bindings package; for
> now it just includes a stub package.
>
> To Do:
> - Have configure detect golang bindings properly
>
> CC: xen-devel <xen-devel@xxxxxxxxxxxxx>
> CC: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: George Dunlap <george.dunlap@xxxxxxxxxx>
> CC: George Dunlap <dunlapg@xxxxxxxxx>
> ---
>  tools/Makefile                    | 16 ++++++++++++++++
>  tools/golang/Makefile             | 33 +++++++++++++++++++++++++++++++++
>  tools/golang/xenlight/xenlight.go |  7 +++++++
>  3 files changed, 56 insertions(+)
>  create mode 100644 tools/golang/Makefile
>  create mode 100644 tools/golang/xenlight/xenlight.go
>
> diff --git a/tools/Makefile b/tools/Makefile
> index 71515b4..f2198e0 100644
> --- a/tools/Makefile
> +++ b/tools/Makefile
> @@ -11,6 +11,8 @@ SUBDIRS-y += misc
>  SUBDIRS-y += examples
>  SUBDIRS-y += hotplug
>  SUBDIRS-y += xentrace
> +SUBDIRS-y += golang
> +#FIXME: Have golang controlled by a configure variable
>  SUBDIRS-$(CONFIG_XCUTILS) += xcutils
>  SUBDIRS-$(CONFIG_X86) += firmware
>  SUBDIRS-y += console
> @@ -311,6 +313,20 @@ subdir-install-debugger/gdbsx: .phony
>  subdir-all-debugger/gdbsx: .phony
>         $(MAKE) -C debugger/gdbsx all
>
> +subdir-all-golang/xenlight: .phony
> +       $(MAKE) -C golang all
> +
> +subdir-clean-golang/xenlight: .phony
> +       $(MAKE) -C golang clean
> +
> +subdir-install-golang/xenlight: .phony
> +       $(MAKE) -C golang install
> +
> +subdir-build-golang/xenlight: .phony
> +       $(MAKE) -C golang build
> +
> +subdir-distclean-golang/xenlight: .phony
> +       $(MAKE) -C golang distclean
>
>  subdir-clean-debugger/kdd subdir-distclean-debugger/kdd: .phony
>         $(MAKE) -C debugger/kdd clean
> diff --git a/tools/golang/Makefile b/tools/golang/Makefile
> new file mode 100644
> index 0000000..eead226
> --- /dev/null
> +++ b/tools/golang/Makefile
> @@ -0,0 +1,33 @@
> +XEN_ROOT=$(CURDIR)/../..
> +include $(XEN_ROOT)/tools/Rules.mk
> +
> +BINARY = xenlight.a
> +GO ?= go
> +
> +.PHONY: all
> +all: build
> +
> +.PHONY: build
> +build: xenlight/xenlight.a

I think eventually we'll want to have a makefile in tools/golang which
calls the makefiles in tools/golang/xenlight and other directories;
but since we have only one at the moment, I think this is probably
fine.

> +.PHONY: install
> +install: build
> +       if [ ! -f $(BINARY) ]; then \
> +               mkdir $(GOPATH)/src/xenlight; \
> +               $(INSTALL_PROG) xenlight/xenlight.go 
> $(GOPATH)/src/xenlight/xenlight.go; \
> +               echo "this"; \
> +       fi

A couple of things.

First, as we discussed on IRC, the if[] clause is not necessary --
make will automatically stop if one of the prerequisites isn't
available.

Secondly -- this is a bit confusing, but the "install" section of the
parts of the tree that actually build things don't install files
directly onto the host filesystem.  Instead, they install into
$(DESTDIR) (which is xen.git/dist/install), and then the final step of
"make install" will copy everything from dist/install into the host
filesystem.

Also, you shouldn't do a plain mkdir, but should use $(INSTALL_DIR).
And since the file you're installing is not going to be executed, you
should use $(INSTALL_DATA).  (I didn't realize that distinction
existed until I looked at tools/libxl/Makefile).

So this should look more like:

install: build
  $(INSTALL_DIR) $(DESTDIR)$(GOLANG_SRC)
  $(INSTALL_DATA) xenlight/xenlight.go $(DESTDIR)$(GOLANG_SRC)

And we want the package name to be "xenproject.org/xenlight", so that
we can put up a repo at git://xenproject.org/xenlight and have people
download it automatically.  So GOLANG_SRC should be set by default to
$(GOPATH)/src/xenproject.org/xenlight

With that done I think we might be ready to add some golang code. :-)

 -George

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