[3/4] samples/bpf: Simplify building BPF samples

Make BPF samples build depend on CONFIG_SAMPLE_BPF. We still don't add a
Kconfig option since that will add a dependency on llvm for allyesconfig
builds which may not be desirable.

Those who need to build the BPF samples can now just do:

make CONFIG_SAMPLE_BPF=y

or:

export CONFIG_SAMPLE_BPF=y
make

Cc: Alexei Starovoitov <ast@fb.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 samples/Makefile     |  2 +-
 samples/bpf/Makefile | 39 ++++++++++++++++++++-------------------
 2 files changed, 21 insertions(+), 20 deletions(-)

On 3/31/16 4:25 AM, Naveen N. Rao wrote:
> Make BPF samples build depend on CONFIG_SAMPLE_BPF. We still don't add a
> Kconfig option since that will add a dependency on llvm for allyesconfig
> builds which may not be desirable.
>
> Those who need to build the BPF samples can now just do:
>
> make CONFIG_SAMPLE_BPF=y
>
> or:
>
> export CONFIG_SAMPLE_BPF=y
> make

I don't like this 'simplification'.
make samples/bpf/
is much easier to type than capital letters.

> diff --git a/samples/Makefile b/samples/Makefile
> index 48001d7..3c77fc8 100644
> --- a/samples/Makefile
> +++ b/samples/Makefile
> @@ -2,4 +2,4 @@
>
>   obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ livepatch/ \
>   			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \
> -			   configfs/
> +			   configfs/ bpf/
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index 88bc5a0..bc5b675 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -2,23 +2,23 @@
>   obj- := dummy.o
>
>   # List of programs to build
> -hostprogs-y := test_verifier test_maps
> -hostprogs-y += sock_example
> -hostprogs-y += fds_example
> -hostprogs-y += sockex1
> -hostprogs-y += sockex2
> -hostprogs-y += sockex3
> -hostprogs-y += tracex1
> -hostprogs-y += tracex2
> -hostprogs-y += tracex3
> -hostprogs-y += tracex4
> -hostprogs-y += tracex5
> -hostprogs-y += tracex6
> -hostprogs-y += trace_output
> -hostprogs-y += lathist
> -hostprogs-y += offwaketime
> -hostprogs-y += spintest
> -hostprogs-y += map_perf_test
> +hostprogs-$(CONFIG_SAMPLE_BPF) := test_verifier test_maps
> +hostprogs-$(CONFIG_SAMPLE_BPF) += sock_example
> +hostprogs-$(CONFIG_SAMPLE_BPF) += fds_example
> +hostprogs-$(CONFIG_SAMPLE_BPF) += sockex1
> +hostprogs-$(CONFIG_SAMPLE_BPF) += sockex2
> +hostprogs-$(CONFIG_SAMPLE_BPF) += sockex3
> +hostprogs-$(CONFIG_SAMPLE_BPF) += tracex1
> +hostprogs-$(CONFIG_SAMPLE_BPF) += tracex2
> +hostprogs-$(CONFIG_SAMPLE_BPF) += tracex3
> +hostprogs-$(CONFIG_SAMPLE_BPF) += tracex4
> +hostprogs-$(CONFIG_SAMPLE_BPF) += tracex5
> +hostprogs-$(CONFIG_SAMPLE_BPF) += tracex6
> +hostprogs-$(CONFIG_SAMPLE_BPF) += trace_output
> +hostprogs-$(CONFIG_SAMPLE_BPF) += lathist
> +hostprogs-$(CONFIG_SAMPLE_BPF) += offwaketime
> +hostprogs-$(CONFIG_SAMPLE_BPF) += spintest
> +hostprogs-$(CONFIG_SAMPLE_BPF) += map_perf_test
>
>   test_verifier-objs := test_verifier.o libbpf.o
>   test_maps-objs := test_maps.o libbpf.o
> @@ -39,8 +39,8 @@ offwaketime-objs := bpf_load.o libbpf.o offwaketime_user.o
>   spintest-objs := bpf_load.o libbpf.o spintest_user.o
>   map_perf_test-objs := bpf_load.o libbpf.o map_perf_test_user.o
>
> -# Tell kbuild to always build the programs
> -always := $(hostprogs-y)
> +ifdef CONFIG_SAMPLE_BPF
> +always := $(hostprogs-$(CONFIG_SAMPLE_BPF))
>   always += sockex1_kern.o
>   always += sockex2_kern.o
>   always += sockex3_kern.o
> @@ -56,6 +56,7 @@ always += lathist_kern.o
>   always += offwaketime_kern.o
>   always += spintest_kern.o
>   always += map_perf_test_kern.o
> +endif
>
>   HOSTCFLAGS += -I$(objtree)/usr/include
>
>

On 2016/03/31 10:49AM, Alexei Starovoitov wrote:
> On 3/31/16 4:25 AM, Naveen N. Rao wrote:
> >Make BPF samples build depend on CONFIG_SAMPLE_BPF. We still don't add a
> >Kconfig option since that will add a dependency on llvm for allyesconfig
> >builds which may not be desirable.
> >
> >Those who need to build the BPF samples can now just do:
> >
> >make CONFIG_SAMPLE_BPF=y
> >
> >or:
> >
> >export CONFIG_SAMPLE_BPF=y
> >make
> 
> I don't like this 'simplification'.
> make samples/bpf/
> is much easier to type than capital letters.

This started out as a patch to have the BPF samples built with a Kconfig 
option. As stated in the commit description, I realised that it won't 
work for allyesconfig builds. However, the reason I retained this patch 
is since it gets us one step closer to building the samples as part of 
the kernel build.

The 'simplification' is since I can now have the export in my .bashrc 
and the kernel build will now build the BPF samples too without 
requiring an additional 'make samples/bpf/' step.

I agree this is subjective, so I am ok if this isn't taken in.


- Naveen

On 3/31/16 11:51 AM, Naveen N. Rao wrote:
> On 2016/03/31 10:49AM, Alexei Starovoitov wrote:
>> On 3/31/16 4:25 AM, Naveen N. Rao wrote:
>>> Make BPF samples build depend on CONFIG_SAMPLE_BPF. We still don't add a
>>> Kconfig option since that will add a dependency on llvm for allyesconfig
>>> builds which may not be desirable.
>>>
>>> Those who need to build the BPF samples can now just do:
>>>
>>> make CONFIG_SAMPLE_BPF=y
>>>
>>> or:
>>>
>>> export CONFIG_SAMPLE_BPF=y
>>> make
>>
>> I don't like this 'simplification'.
>> make samples/bpf/
>> is much easier to type than capital letters.
>
> This started out as a patch to have the BPF samples built with a Kconfig
> option. As stated in the commit description, I realised that it won't
> work for allyesconfig builds. However, the reason I retained this patch
> is since it gets us one step closer to building the samples as part of
> the kernel build.
>
> The 'simplification' is since I can now have the export in my .bashrc
> and the kernel build will now build the BPF samples too without
> requiring an additional 'make samples/bpf/' step.
>
> I agree this is subjective, so I am ok if this isn't taken in.

If you can change it that 'make samples/bpf/' still works then it would
be fine. As it is it breaks our testing setup.