linux-kernel - Re: [PATCH v3] tools/dma: move dma_map_benchmark from selftests to tools/dma

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Message-ID: <CAGsJ_4zf31seJif1N93yk_mUaEYh4SzwedASK9VPnPm_JJ6t3Q@mail.gmail.com>
Date: Tue, 21 Oct 2025 19:23:40 +1300
From: Barry Song <21cnbao@...il.com>
To: Qinxin Xia <xiaqinxin@...wei.com>
Cc: m.szyprowski@...sung.com, robin.murphy@....com, prime.zeng@...wei.com, 
	fanghao11@...wei.com, linux-kernel@...r.kernel.org, linuxarm@...wei.com, 
	wangzhou1@...ilicon.com
Subject: Re: [PATCH v3] tools/dma: move dma_map_benchmark from selftests to tools/dma

On Tue, Oct 21, 2025 at 6:16 PM Qinxin Xia <xiaqinxin@...wei.com> wrote:
>
>
>
> On 2025/10/21 10:59:05, Barry Song <21cnbao@...il.com> wrote:
> >> @@ -0,0 +1,2 @@
> >> +# SPDX-License-Identifier: GPL-2.0-only
> >> +dma_map_benchmark
> >> diff --git a/tools/dma/Makefile b/tools/dma/Makefile
> >> new file mode 100644
> >> index 000000000000..4acbd9e00cfa
> >> --- /dev/null
> >> +++ b/tools/dma/Makefile
> >> @@ -0,0 +1,17 @@
> >> +# SPDX-License-Identifier: GPL-2.0
> >> +bindir ?= /usr/bin
> >> +
> >> +CFLAGS += -idirafter../../include/uapi
> >
> > I'm a bit confused — it seems you haven’t tried to understand what the issue
> > was in v1 [1]. You were using -I for kernel header files (under
> > include/linux but not uapi), which caused those kernel headers to take
> > precedence over the system headers, leading to build errors. The uapi
> > headers, however, are specifically designed to be installed into the system by
> > the toolchain.
> > So that’s no longer the case — -idirafter is not the correct flag for uapi.
> >
> Hello Barry :
> If I delete -idirafter, like:
>
> CFLAGS += -I../../include/uapi
>
> It will get warning info:
>
> [xiaqinxin@...alhost dma]$ make
> cc -I../../include/uapi dma_map_benchmark.c -o dma_map_benchmark
> In file included from ../../include/uapi/linux/map_benchmark.h:9,
>                   from dma_map_benchmark.c:13:
> ../../include/uapi/linux/types.h:10:2: warning: #warning "Attempt to use
> kernel headers from user space, see https://kernelnewbies.org/
> KernelHeaders" [-Wcpp]
>     10 | #warning "Attempt to use kernel headers from user space, see
> https://kernelnewbies.org/KernelHeaders"
>
> So I keep -idirafter there.
>
> There's another way, like:
>
> CFLAGS += -I../../usr/include
> (need make headers_install first)
>
> Maybe I haven’t thought it through.
> If you have a better way, you can give an example.:)

I see — the uapi headers haven’t been installed yet. This issue will
automatically resolve once the toolchain is upgraded. Before that, we
can try the following:

tools/gpio/Makefile

#
# We need the following to be outside of kernel tree
#
$(OUTPUT)include/linux/gpio.h: ../../include/uapi/linux/gpio.h
        mkdir -p $(OUTPUT)include/linux 2>&1 || true
        ln -sf $(CURDIR)/../../include/uapi/linux/gpio.h $@

prepare: $(OUTPUT)include/linux/gpio.h

I guess we could copy and paste GPIO’s Makefile and make a few minor
modifications?

>
> >> index b12f1f9babf8..5474a450863c 100644
> >> --- a/tools/testing/selftests/dma/dma_map_benchmark.c
> >> +++ b/tools/dma/dma_map_benchmark.c
> >> @@ -10,7 +10,6 @@
> >>   #include <unistd.h>
> >>   #include <sys/ioctl.h>
> >>   #include <sys/mman.h>
> >> -#include <linux/types.h>
> >
> > What’s the reason for this? Is it to work around a build error?
> > If so, no — please keep it.
> >
> >>   #include <linux/map_benchmark.h>
> >
>
> Moved it to map_benchmark.h, otherwise some x86_64 build errors
> would occur.

Let’s avoid moving types.h — that feels more like a workaround than a
proper fix.

Thanks
Barry