Re: [PATCH] tools/dma: fix building from the top level with O=

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] tools/dma: incomplete fix for out-of-tree (O=) builds
--

commit f9ebfb989b6d469df7135b7ea719817656f0b606
Author: Sasha Levin <sashal@kernel.org>

tools/dma: fix building from the top level with O=

This commit attempts to fix the out-of-tree build for tools/dma when using
O=<dir> by correctly setting the srctree variable. It ensures that srctree
is worked out even when it is empty or when building_out_of_srctree is set.

> diff --git a/tools/dma/Makefile b/tools/dma/Makefile
> index e4abf37bf020c..b5fe6e2625eef 100644
> --- a/tools/dma/Makefile
> +++ b/tools/dma/Makefile
> @@ -7,7 +7,13 @@ bindir ?= /usr/bin
>  # isn't set and when invoked from selftests build, where srctree
>  # is set to ".". building_out_of_srctree is undefined for in srctree
>  # builds
> +ifeq ($(srctree),)
> +update_srctree := 1
> +endif
>  ifndef building_out_of_srctree
> +update_srctree := 1
> +endif
> +ifeq ($(update_srctree),1)
>  srctree := $(patsubst %/,%,$(dir $(CURDIR)))
>  srctree := $(patsubst %/,%,$(dir $(srctree)))
>  endif

[Severity: Low]
Does this commit completely fix the out-of-tree (O=) builds?

While this resolves the srctree issue to successfully locate Makefile.include,
an out-of-tree build via O=<dir> will still fail immediately afterwards.

The default all target depends on $(ALL_PROGRAMS), which correctly expands to
include $(OUTPUT) (e.g., out/.../dma_map_benchmark). However, the explicit
build rule for $(DMA_MAP_BENCHMARK) lacks the $(OUTPUT) prefix:

tools/dma/Makefile:
    DMA_MAP_BENCHMARK = dma_map_benchmark
    $(DMA_MAP_BENCHMARK): prepare FORCE
        $(CC) $(CFLAGS) $(DMA_MAP_BENCHMARK).c -o $(DMA_MAP_BENCHMARK)

As a result, Make will abort with a 'No rule to make target' error.

Furthermore, the compilation command places the resulting binary back in the
source tree instead of the requested output directory.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261011223358.2327625-4-sashal@kernel.org?part=1