Re: [Qemu-devel] [PATCH v4 1/8] make: move top level dir to end of include search path

[Alberto Garcia]

On Wed, Jan 25, 2017 at 04:14:10PM +0000, Daniel P. Berrange wrote:

> One final complication is that the absolute '-I$(BUILD_DIR)/$(@D)'
> will sometimes end up pointing to a non-existant directory if
> that sub-dir does not have any target-independant files to be
> built. Rather than try to dynamically filter this, a simple
> 'mkdir' ensures $(BUILD_DIR)/$(@D) is guaranteed to exist at
> all times.
> 
> @@ -359,6 +374,7 @@ define unnest-vars
>                  $(eval $(o:%.mo=%$(DSOSUF)): module-common.o $($o-objs)),
>                  $(error $o added in $v but $o-objs is not set)))
>          $(shell mkdir -p ./ $(sort $(dir $($v))))
> +        $(shell cd $(BUILD_DIR) && mkdir -p ./ $(sort $(dir $($v))))
>          # Include all the .d files
>          $(eval -include $(patsubst %.o,%.d,$(patsubst %.mo,%.d,$($v))))
>          $(eval $v := $(filter-out %/,$($v))))

After this change building QEMU leaves a lot of empty directories in
the parent directory:

$ mkdir empty_dir
$ cd empty_dir
$ git clone https://github.com/qemu/qemu
$ cd qemu
$ ./configure ...
$ ls ..
qemu
$ make
$ ls ..
audio     chardev  fsdev  linux-user  net   qom     target
backends  crypto   hw     migration   qapi  replay  ui
block     disas    io     nbd         qemu  slirp   util

Berto