[PATCH] samples: bpf: fix outdated README build command

[PATCH] samples: bpf: fix outdated README build command

[Daniel T. Lee]

Currently, building the bpf samples under samples/bpf directory isn't
working. Running make from the directory 'samples/bpf' will just shows
following result without compiling any samples.

 $ make
 make -C ../../ /git/linux/samples/bpf/ BPF_SAMPLES_PATH=/git/linux/samples/bpf
 make[1]: Entering directory '/git/linux'
   CALL    scripts/checksyscalls.sh
   CALL    scripts/atomic/check-atomics.sh
   DESCEND  objtool
 make[1]: Leaving directory '/git/linux'

Due to commit 394053f4a4b3 ("kbuild: make single targets work more
correctly"), building samples/bpf without support of samples/Makefile
is unavailable. Instead, building the samples with 'make M=samples/bpf'
from the root source directory will solve this issue.[1]

This commit fixes the outdated README build command with samples/bpf.

[0]: https://patchwork.kernel.org/patch/11168393/

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
---
 samples/bpf/README.rst | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/samples/bpf/README.rst b/samples/bpf/README.rst
index 5f27e4faca50..bfd2405705ed 100644
--- a/samples/bpf/README.rst
+++ b/samples/bpf/README.rst
@@ -32,12 +32,10 @@ Compiling
 For building the BPF samples, issue the below command from the kernel
 top level directory::
 
- make samples/bpf/
+ make M=samples/bpf
 
-Do notice the "/" slash after the directory name.
-
-It is also possible to call make from this directory.  This will just
-hide the the invocation of make as above with the appended "/".
+Due to samples/bpf cannot be built without support in the
+samples/Makefile, it is unavailable to call make from this directory.
 
 Manually compiling LLVM with 'bpf' support
 ------------------------------------------
@@ -63,14 +61,15 @@ Quick sniplet for manually compiling LLVM and clang
 It is also possible to point make to the newly compiled 'llc' or
 'clang' command via redefining LLC or CLANG on the make command line::
 
- make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
+ make M=samples/bpf LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
 
 Cross compiling samples
 -----------------------
 In order to cross-compile, say for arm64 targets, export CROSS_COMPILE and ARCH
 environment variables before calling make. This will direct make to build
-samples for the cross target.
+samples for the cross target.::
+
+ export ARCH=arm64
+ export CROSS_COMPILE="aarch64-linux-gnu-"
+ make M=samples/bpf LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
 
-export ARCH=arm64
-export CROSS_COMPILE="aarch64-linux-gnu-"
-make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
-- 
2.20.1

Re: [PATCH] samples: bpf: fix outdated README build command

[Andrii Nakryiko]

On Sun, Nov 10, 2019 at 12:19 AM Daniel T. Lee <danieltimlee@gmail.com> wrote:
>
> Currently, building the bpf samples under samples/bpf directory isn't
> working. Running make from the directory 'samples/bpf' will just shows
> following result without compiling any samples.
>

Do you mind trying to see if it's possible to detect that plain `make`
is being run from samples/bpf subdirectory, and if that's the case,
just running something like `make M=samples/bpf -C ../../`? If that's
not too hard, it would be a nice touch to still have it working old
(and intuitive) way, IMO.


>  $ make
>  make -C ../../ /git/linux/samples/bpf/ BPF_SAMPLES_PATH=/git/linux/samples/bpf
>  make[1]: Entering directory '/git/linux'
>    CALL    scripts/checksyscalls.sh
>    CALL    scripts/atomic/check-atomics.sh
>    DESCEND  objtool
>  make[1]: Leaving directory '/git/linux'
>
> Due to commit 394053f4a4b3 ("kbuild: make single targets work more
> correctly"), building samples/bpf without support of samples/Makefile
> is unavailable. Instead, building the samples with 'make M=samples/bpf'
> from the root source directory will solve this issue.[1]
>
> This commit fixes the outdated README build command with samples/bpf.
>
> [0]: https://patchwork.kernel.org/patch/11168393/
>
> Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
> ---
>  samples/bpf/README.rst | 19 +++++++++----------
>  1 file changed, 9 insertions(+), 10 deletions(-)
>

[...]

Re: [PATCH] samples: bpf: fix outdated README build command

[Toke Høiland-Jørgensen]

Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:

> On Sun, Nov 10, 2019 at 12:19 AM Daniel T. Lee <danieltimlee@gmail.com> wrote:
>>
>> Currently, building the bpf samples under samples/bpf directory isn't
>> working. Running make from the directory 'samples/bpf' will just shows
>> following result without compiling any samples.
>>
>
> Do you mind trying to see if it's possible to detect that plain `make`
> is being run from samples/bpf subdirectory, and if that's the case,
> just running something like `make M=samples/bpf -C ../../`? If that's
> not too hard, it would be a nice touch to still have it working old
> (and intuitive) way, IMO.

I think it's just the M= that's missing. Tentatively, the below seems to
work for me (I get some other compile errors, but I think that is
unrelated).

-Toke


diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 8a9af3ab7769..48e7f1ff7861 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -246,7 +246,7 @@ endif
 
 # Trick to allow make to be run from this directory
 all:
-       $(MAKE) -C ../../ $(CURDIR)/ BPF_SAMPLES_PATH=$(CURDIR)
+       $(MAKE) -C ../../ M=$(CURDIR) BPF_SAMPLES_PATH=$(CURDIR)
 
 clean:
        $(MAKE) -C ../../ M=$(CURDIR) clean

Re: [PATCH] samples: bpf: fix outdated README build command

[Daniel Borkmann]

On 11/10/19 9:19 AM, Daniel T. Lee wrote:
> Currently, building the bpf samples under samples/bpf directory isn't
> working. Running make from the directory 'samples/bpf' will just shows
> following result without compiling any samples.
> 
>   $ make
>   make -C ../../ /git/linux/samples/bpf/ BPF_SAMPLES_PATH=/git/linux/samples/bpf
>   make[1]: Entering directory '/git/linux'
>     CALL    scripts/checksyscalls.sh
>     CALL    scripts/atomic/check-atomics.sh
>     DESCEND  objtool
>   make[1]: Leaving directory '/git/linux'
> 
> Due to commit 394053f4a4b3 ("kbuild: make single targets work more
> correctly"), building samples/bpf without support of samples/Makefile
> is unavailable. Instead, building the samples with 'make M=samples/bpf'
> from the root source directory will solve this issue.[1]
> 
> This commit fixes the outdated README build command with samples/bpf.
> 
> [0]: https://patchwork.kernel.org/patch/11168393/
> 
> Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>

Thanks for the patch, Daniel! Looks like it's not rebased to the latest bpf-next
tree and therefore doesn't apply cleanly.

Meanwhile, https://patchwork.ozlabs.org/patch/1192639/ was sent which addresses
the same issue.

Best,
Daniel

Re: [PATCH] samples: bpf: fix outdated README build command

[Daniel T. Lee]

On Mon, Nov 11, 2019 at 3:09 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Sun, Nov 10, 2019 at 12:19 AM Daniel T. Lee <danieltimlee@gmail.com> wrote:
> >
> > Currently, building the bpf samples under samples/bpf directory isn't
> > working. Running make from the directory 'samples/bpf' will just shows
> > following result without compiling any samples.
> >
>
> Do you mind trying to see if it's possible to detect that plain `make`
> is being run from samples/bpf subdirectory, and if that's the case,
> just running something like `make M=samples/bpf -C ../../`? If that's
> not too hard, it would be a nice touch to still have it working old
> (and intuitive) way, IMO.
>

Thanks for the review!
And seems it works with `make M=samples/bpf -C ../../` and it's better
solution!

It's just the issue has been solved as Daniel Borkmann mentioned.
Anyway, thanks for the review!

Best,
Daniel

>
> >  $ make
> >  make -C ../../ /git/linux/samples/bpf/ BPF_SAMPLES_PATH=/git/linux/samples/bpf
> >  make[1]: Entering directory '/git/linux'
> >    CALL    scripts/checksyscalls.sh
> >    CALL    scripts/atomic/check-atomics.sh
> >    DESCEND  objtool
> >  make[1]: Leaving directory '/git/linux'
> >
> > Due to commit 394053f4a4b3 ("kbuild: make single targets work more
> > correctly"), building samples/bpf without support of samples/Makefile
> > is unavailable. Instead, building the samples with 'make M=samples/bpf'
> > from the root source directory will solve this issue.[1]
> >
> > This commit fixes the outdated README build command with samples/bpf.
> >
> > [0]: https://patchwork.kernel.org/patch/11168393/
> >
> > Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
> > ---
> >  samples/bpf/README.rst | 19 +++++++++----------
> >  1 file changed, 9 insertions(+), 10 deletions(-)
> >
>
> [...]

Re: [PATCH] samples: bpf: fix outdated README build command

[Daniel T. Lee]

On Mon, Nov 11, 2019 at 6:24 PM Toke Høiland-Jørgensen
<thoiland@redhat.com> wrote:
>
> Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:
>
> > On Sun, Nov 10, 2019 at 12:19 AM Daniel T. Lee <danieltimlee@gmail.com> wrote:
> >>
> >> Currently, building the bpf samples under samples/bpf directory isn't
> >> working. Running make from the directory 'samples/bpf' will just shows
> >> following result without compiling any samples.
> >>
> >
> > Do you mind trying to see if it's possible to detect that plain `make`
> > is being run from samples/bpf subdirectory, and if that's the case,
> > just running something like `make M=samples/bpf -C ../../`? If that's
> > not too hard, it would be a nice touch to still have it working old
> > (and intuitive) way, IMO.
>
> I think it's just the M= that's missing. Tentatively, the below seems to
> work for me (I get some other compile errors, but I think that is
> unrelated).
>
> -Toke
>
>

Thanks for the review!
Modifying the Makefile seems better solution!

Again, It's just the issue has been solved as Daniel Borkmann mentioned.
Thanks for the review!

Best,
Daniel

> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index 8a9af3ab7769..48e7f1ff7861 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -246,7 +246,7 @@ endif
>
>  # Trick to allow make to be run from this directory
>  all:
> -       $(MAKE) -C ../../ $(CURDIR)/ BPF_SAMPLES_PATH=$(CURDIR)
> +       $(MAKE) -C ../../ M=$(CURDIR) BPF_SAMPLES_PATH=$(CURDIR)
>
>  clean:
>         $(MAKE) -C ../../ M=$(CURDIR) clean
>

Re: [PATCH] samples: bpf: fix outdated README build command

[Daniel T. Lee]

On Mon, Nov 11, 2019 at 10:58 PM Daniel Borkmann <daniel@iogearbox.net> wrote:
>
> On 11/10/19 9:19 AM, Daniel T. Lee wrote:
> > Currently, building the bpf samples under samples/bpf directory isn't
> > working. Running make from the directory 'samples/bpf' will just shows
> > following result without compiling any samples.
> >
> >   $ make
> >   make -C ../../ /git/linux/samples/bpf/ BPF_SAMPLES_PATH=/git/linux/samples/bpf
> >   make[1]: Entering directory '/git/linux'
> >     CALL    scripts/checksyscalls.sh
> >     CALL    scripts/atomic/check-atomics.sh
> >     DESCEND  objtool
> >   make[1]: Leaving directory '/git/linux'
> >
> > Due to commit 394053f4a4b3 ("kbuild: make single targets work more
> > correctly"), building samples/bpf without support of samples/Makefile
> > is unavailable. Instead, building the samples with 'make M=samples/bpf'
> > from the root source directory will solve this issue.[1]
> >
> > This commit fixes the outdated README build command with samples/bpf.
> >
> > [0]: https://patchwork.kernel.org/patch/11168393/
> >
> > Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
>
> Thanks for the patch, Daniel! Looks like it's not rebased to the latest bpf-next
> tree and therefore doesn't apply cleanly.
>
> Meanwhile, https://patchwork.ozlabs.org/patch/1192639/ was sent which addresses
> the same issue.
>
> Best,
> Daniel

Thanks for the review.
Seems the issue has been already solved!