[PATCH v2 0/6] kbuild: use target compiler for user binaries in samples/

[PATCH v2 0/6] kbuild: use target compiler for user binaries in samples/

[Sam Ravnborg]

[PATCH v2 0/6] kbuild: use target compiler for user binaries in samples/

The user-space binaries build in samples/ uses the installed
headers for the kernel.
Therefore it is wrong that they use the host compiler
to build the samples.

This set of patches add kbuild support for building
the userspace programs.
They are build with same endian and bit-size as the kernel,
so in other words no support for buildign 32 bit userspace for
a 64 bit kernel.
The majority of the patch is the Documentation changes,
especially because a new chapter was added.

NOTE: This will likely break the build if the toolchain used do
not include a libc. Let's see how much noise this creates.

I have included a few moe people in this submission as
I assume this has their interest.

Michal - I hope you can take this via the kbuild#misc
tree when any feedback has been addressed.

Changes since first posting (https://lkml.org/lkml/2013/3/31/74):
- Use $(biarch) in X86_32 (feedback from Michael Marek)
- Drop sub-directory support (feedback from Michael Marek)
  o This simplified the uapi support a lot
- Fix clean support (feedback from Michael Marek)
- Added documentation to Documentation/kbuild/
- Use $(CC) as there is no need for a dedicated UAPICC
- Prefer foobar-y over foobar-objs for specifying .o files
  for a binary
- Move cc options to Makefile.uapiprogs and only use -Wall
- Use -isystem to include installed uapi headers before headers
  provided by the installed libc
- Divided up in smaller patches to ease review

	Sam

Sam Ravnborg (6):
      kbuild: add support for building userspace api programs
      samples: refactor Makefile
      samples: use uapiprogs support for seccomp
      samples: use uapiprogs support for hidraw
      samples: fix warnings in uhid-example
      samples: use uapiprogs support for uhid

 Documentation/kbuild/kbuild.txt    |   5 ++
 Documentation/kbuild/makefiles.txt | 132 ++++++++++++++++++++++++-------------
 Makefile                           |   4 ++
 arch/s390/Makefile                 |   2 +
 arch/sparc/Makefile                |   2 +
 arch/x86/Makefile                  |   2 +
 samples/Makefile                   |  16 ++++-
 samples/hidraw/Makefile            |  11 +---
 samples/seccomp/Makefile           |  48 +-------------
 samples/uhid/Makefile              |  11 +---
 samples/uhid/uhid-example.c        |   9 ++-
 scripts/Makefile.build             |   4 ++
 scripts/Makefile.clean             |   9 +--
 scripts/Makefile.uapiprogs         |  63 ++++++++++++++++++
 14 files changed, 196 insertions(+), 122 deletions(-)

[PATCH 1/6] kbuild: add support for building userspace api programs

[Sam Ravnborg]

Add dedicated support for building the usersapce api sample
programs that is located in samples/
The dedicated kbuild support allows us to use much simpler
Makefile fragments while building the userspace programs for
the same host as the kernel.

The syntax looks like this:

    uapiprogs-y := hid-example

This will build the userspace program hid-example from
hid-example.c and include files will be preferred from
the exported uapi headers.

The userspace sample programs rely on the exported uapi
header files and thus are supposed to be built for the
same architecture as the kernel. Bit bit-size will be the
same as used for the kernel so there is no support for
building 32 bit binaries for a 64 bit kernel.

To build the userspace programs the toolchain needs to
include support for this - so this change will break
the build for the setups that rely on toolchain without
any libc included.

One fix for this would be to add a libc to the kernel,
but this seems to be a rather drastic measure just to support
building a few sample programs.
The better fix is to use toolchains with libc support.

This patch introduces only the infrastructure - including
the setup for various architectures to specify -m option.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
---
 Documentation/kbuild/kbuild.txt    |   5 ++
 Documentation/kbuild/makefiles.txt | 132 ++++++++++++++++++++++++-------------
 Makefile                           |   4 ++
 arch/s390/Makefile                 |   2 +
 arch/sparc/Makefile                |   2 +
 arch/x86/Makefile                  |   2 +
 scripts/Makefile.build             |   4 ++
 scripts/Makefile.clean             |   9 +--
 scripts/Makefile.uapiprogs         |  63 ++++++++++++++++++
 9 files changed, 172 insertions(+), 51 deletions(-)
 create mode 100644 scripts/Makefile.uapiprogs

diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 6466704..6b691d3b 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -233,3 +233,8 @@ KBUILD_VMLINUX_MAIN
 All object files for the main part of vmlinux.
 KBUILD_VMLINUX_INIT and KBUILD_VMLINUX_MAIN together specify
 all the object files used to link vmlinux.
+
+UAPICFLAGS
+--------------------------------------------------
+Arch specific flags used when building sample binaries.
+This is usually the machine size (32 versus 64 bit).
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index c600e2f..713ea10 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -29,30 +29,32 @@ This document describes the Linux kernel Makefiles.
 	   --- 4.6 When host programs are actually built
 	   --- 4.7 Using hostprogs-$(CONFIG_FOO)
 
-	=== 5 Kbuild clean infrastructure
-
-	=== 6 Architecture Makefiles
-	   --- 6.1 Set variables to tweak the build to the architecture
-	   --- 6.2 Add prerequisites to archheaders:
-	   --- 6.3 Add prerequisites to archprepare:
-	   --- 6.4 List directories to visit when descending
-	   --- 6.5 Architecture-specific boot images
-	   --- 6.6 Building non-kbuild targets
-	   --- 6.7 Commands useful for building a boot image
-	   --- 6.8 Custom kbuild commands
-	   --- 6.9 Preprocessing linker scripts
-	   --- 6.10 Generic header files
-
-	=== 7 Kbuild syntax for exported headers
-		--- 7.1 header-y
-		--- 7.2 genhdr-y
-		--- 7.3 destination-y
-		--- 7.4 generic-y
-
-	=== 8 Kbuild Variables
-	=== 9 Makefile language
-	=== 10 Credits
-	=== 11 TODO
+	=== 5 Samples support (uapiprogs-y)
+
+	=== 6 Kbuild clean infrastructure
+
+	=== 7 Architecture Makefiles
+	   --- 7.1 Set variables to tweak the build to the architecture
+	   --- 7.2 Add prerequisites to archheaders:
+	   --- 7.3 Add prerequisites to archprepare:
+	   --- 7.4 List directories to visit when descending
+	   --- 7.5 Architecture-specific boot images
+	   --- 7.6 Building non-kbuild targets
+	   --- 7.7 Commands useful for building a boot image
+	   --- 7.8 Custom kbuild commands
+	   --- 7.9 Preprocessing linker scripts
+	   --- 7.10 Generic header files
+
+	=== 8 Kbuild syntax for exported headers
+		--- 8.1 header-y
+		--- 8.2 genhdr-y
+		--- 8.3 destination-y
+		--- 8.4 generic-y
+
+	=== 9 Kbuild Variables
+	=== 10 Makefile language
+	=== 11 Credits
+	=== 12 TODO
 
 === 1 Overview
 
@@ -761,7 +763,43 @@ Both possibilities are described in the following.
 	like hostprogs-y. But only hostprogs-y is recommended to be used
 	when no CONFIG symbols are involved.
 
-=== 5 Kbuild clean infrastructure
+=== 5 Samples support (uapiprogs-y)
+
+Kbuild support building sample modules and sample binaries.
+To build sample modules the existing infrastructure is used, but
+to build sample binaries kbuild adds dedicated suppport.
+
+The sample binaries are build for the same host and bit-size as the kernel.
+
+The samples may demonstrate facilities not yet available
+in the installed libc therefore they are build so they include
+headers from the exported uapi headers before the libc headers
+are searched.
+
+The sample binaries are usually placed in sub-directories
+below samples/ and specified in samples/Makefile.
+The directories containing sample binaries are listed using
+subdir-y - usually like this: subdir-$(CONFIG_SAMPLES) += dir
+
+The individual binaries may be defined as single .c file per binary
+or several .c files for a single binary.
+See the following examples.
+
+	Example:
+		# samples/hid/Makefile
+		uapiprogs-y := hid-example
+
+	This will compile hid-example.c and create an executable named hid-example.
+
+	Example:
+		# samples/seccomp/Makefile
+		uapiprogs-y := bpf-fancy
+		bpf-fancy-y := bpf-fancy.o bpf-helper.o
+
+This will compile bpf-fancy.c and bpf-helper.c, and then link the executable
+bpf-fancy, based on bpf-fancy.o bpf-helper.o.
+
+=== 6 Kbuild clean infrastructure
 
 "make clean" deletes most generated files in the obj tree where the kernel
 is compiled. This includes generated files such as host programs.
@@ -828,7 +866,7 @@ is not operational at that point.
 Note 2: All directories listed in core-y, libs-y, drivers-y and net-y will
 be visited during "make clean".
 
-=== 6 Architecture Makefiles
+=== 7 Architecture Makefiles
 
 The top level Makefile sets up the environment and does the preparation,
 before starting to descend down in the individual directories.
@@ -857,7 +895,7 @@ When kbuild executes, the following steps are followed (roughly):
    - Preparing initrd images and the like
 
 
---- 6.1 Set variables to tweak the build to the architecture
+--- 7.1 Set variables to tweak the build to the architecture
 
     LDFLAGS		Generic $(LD) options
 
@@ -976,7 +1014,7 @@ When kbuild executes, the following steps are followed (roughly):
 	$(KBUILD_ARFLAGS) set by the top level Makefile to "D" (deterministic
 	mode) if this option is supported by $(AR).
 
---- 6.2 Add prerequisites to archheaders:
+--- 7.2 Add prerequisites to archheaders:
 
 	The archheaders: rule is used to generate header files that
 	may be installed into user space by "make header_install" or
@@ -989,7 +1027,7 @@ When kbuild executes, the following steps are followed (roughly):
 	architecture itself.
 
 
---- 6.3 Add prerequisites to archprepare:
+--- 7.3 Add prerequisites to archprepare:
 
 	The archprepare: rule is used to list prerequisites that need to be
 	built before starting to descend down in the subdirectories.
@@ -1005,7 +1043,7 @@ When kbuild executes, the following steps are followed (roughly):
 	generating offset header files.
 
 
---- 6.4 List directories to visit when descending
+--- 7.4 List directories to visit when descending
 
 	An arch Makefile cooperates with the top Makefile to define variables
 	which specify how to build the vmlinux file.  Note that there is no
@@ -1034,7 +1072,7 @@ When kbuild executes, the following steps are followed (roughly):
 		drivers-$(CONFIG_OPROFILE)  += arch/sparc64/oprofile/
 
 
---- 6.5 Architecture-specific boot images
+--- 7.5 Architecture-specific boot images
 
 	An arch Makefile specifies goals that take the vmlinux file, compress
 	it, wrap it in bootstrapping code, and copy the resulting files
@@ -1085,7 +1123,7 @@ When kbuild executes, the following steps are followed (roughly):
 
 	When "make" is executed without arguments, bzImage will be built.
 
---- 6.6 Building non-kbuild targets
+--- 7.6 Building non-kbuild targets
 
     extra-y
 
@@ -1105,7 +1143,7 @@ When kbuild executes, the following steps are followed (roughly):
 	shall be built, but shall not be linked as part of built-in.o.
 
 
---- 6.7 Commands useful for building a boot image
+--- 7.7 Commands useful for building a boot image
 
 	Kbuild provides a few macros that are useful when building a
 	boot image.
@@ -1127,7 +1165,7 @@ When kbuild executes, the following steps are followed (roughly):
 	always be built.
 	Assignments to $(targets) are without $(obj)/ prefix.
 	if_changed may be used in conjunction with custom commands as
-	defined in 6.8 "Custom kbuild commands".
+	defined in 7.8 "Custom kbuild commands".
 
 	Note: It is a typical mistake to forget the FORCE prerequisite.
 	Another common pitfall is that whitespace is sometimes
@@ -1210,7 +1248,7 @@ When kbuild executes, the following steps are followed (roughly):
 	A central rule exists to create $(obj)/%.dtb from $(src)/%.dtsp;
 	architecture Makefiles do no need to explicitly write out that rule.
 
---- 6.8 Custom kbuild commands
+--- 7.8 Custom kbuild commands
 
 	When kbuild is executing with KBUILD_VERBOSE=0, then only a shorthand
 	of a command is normally displayed.
@@ -1237,7 +1275,7 @@ When kbuild executes, the following steps are followed (roughly):
 	will be displayed with "make KBUILD_VERBOSE=0".
 
 
---- 6.9 Preprocessing linker scripts
+--- 7.9 Preprocessing linker scripts
 
 	When the vmlinux image is built, the linker script
 	arch/$(ARCH)/kernel/vmlinux.lds is used.
@@ -1267,15 +1305,15 @@ When kbuild executes, the following steps are followed (roughly):
 	The kbuild infrastructure for *lds file are used in several
 	architecture-specific files.
 
---- 6.10 Generic header files
+--- 7.10 Generic header files
 
 	The directory include/asm-generic contains the header files
 	that may be shared between individual architectures.
 	The recommended approach how to use a generic header file is
 	to list the file in the Kbuild file.
-	See "7.4 generic-y" for further info on syntax etc.
+	See "8.4 generic-y" for further info on syntax etc.
 
-=== 7 Kbuild syntax for exported headers
+=== 8 Kbuild syntax for exported headers
 
 The kernel include a set of headers that is exported to userspace.
 Many headers can be exported as-is but other headers require a
@@ -1289,7 +1327,7 @@ Each relevant directory contains a file name "Kbuild" which specifies the
 headers to be exported.
 See subsequent chapter for the syntax of the Kbuild file.
 
-	--- 7.1 header-y
+	--- 8.1 header-y
 
 	header-y specify header files to be exported.
 
@@ -1307,7 +1345,7 @@ See subsequent chapter for the syntax of the Kbuild file.
 
 	Subdirectories are visited before their parent directories.
 
-	--- 7.2 genhdr-y
+	--- 8.2 genhdr-y
 
 	genhdr-y specifies generated files to be exported.
 	Generated files are special as they need to be looked
@@ -1317,7 +1355,7 @@ See subsequent chapter for the syntax of the Kbuild file.
 			#include/linux/Kbuild
 			genhdr-y += version.h
 
-	--- 7.3 destination-y
+	--- 8.3 destination-y
 
 	When an architecture have a set of exported headers that needs to be
 	exported to a different directory destination-y is used.
@@ -1331,7 +1369,7 @@ See subsequent chapter for the syntax of the Kbuild file.
 	In the example above all exported headers in the Kbuild file
 	will be located in the directory "include/linux" when exported.
 
-	--- 7.4 generic-y
+	--- 8.4 generic-y
 
 	If an architecture uses a verbatim copy of a header from
 	include/asm-generic then this is listed in the file
@@ -1358,7 +1396,7 @@ See subsequent chapter for the syntax of the Kbuild file.
 		Example: termios.h
 			#include <asm-generic/termios.h>
 
-=== 8 Kbuild Variables
+=== 9 Kbuild Variables
 
 The top Makefile exports the following variables:
 
@@ -1421,7 +1459,7 @@ The top Makefile exports the following variables:
 	command.
 
 
-=== 9 Makefile language
+=== 10 Makefile language
 
 The kernel Makefiles are designed to be run with GNU Make.  The Makefiles
 use only the documented features of GNU Make, but they do use many
@@ -1440,14 +1478,14 @@ time the left-hand side is used.
 There are some cases where "=" is appropriate.  Usually, though, ":="
 is the right choice.
 
-=== 10 Credits
+=== 11 Credits
 
 Original version made by Michael Elizabeth Chastain, <mailto:mec@shout.net>
 Updates by Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de>
 Updates by Sam Ravnborg <sam@ravnborg.org>
 Language QA by Jan Engelhardt <jengelh@gmx.de>
 
-=== 11 TODO
+=== 12 TODO
 
 - Describe how kbuild supports shipped files with _shipped.
 - Generating offset header files.
diff --git a/Makefile b/Makefile
index 4d75b4b..7fda2ba 100644
--- a/Makefile
+++ b/Makefile
@@ -935,8 +935,12 @@ prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
 
 archprepare: archheaders archscripts prepare1 scripts_basic
 
+# To build userspace samples the uapi headers needs to be exported
 prepare0: archprepare FORCE
 	$(Q)$(MAKE) $(build)=.
+ifdef CONFIG_SAMPLES
+	$(Q)$(MAKE) KBUILD_SRC= headers_install
+endif
 
 # All the preparing..
 prepare: prepare0
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 874e6d6..4b32933 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -18,6 +18,7 @@ LD_BFD		:= elf32-s390
 LDFLAGS		:= -m elf_s390
 KBUILD_CFLAGS	+= -m31
 KBUILD_AFLAGS	+= -m31
+UAPICFLAGS	+= -m31
 UTS_MACHINE	:= s390
 STACK_SIZE	:= 8192
 CHECKFLAGS	+= -D__s390__ -msize-long
@@ -28,6 +29,7 @@ KBUILD_AFLAGS_MODULE += -fPIC
 KBUILD_CFLAGS_MODULE += -fPIC
 KBUILD_CFLAGS	+= -m64
 KBUILD_AFLAGS	+= -m64
+UAPICFLAGS	+= -m64
 UTS_MACHINE	:= s390x
 STACK_SIZE	:= 16384
 CHECKFLAGS	+= -D__s390__ -D__s390x__
diff --git a/arch/sparc/Makefile b/arch/sparc/Makefile
index 9ff4236..08a5f78 100644
--- a/arch/sparc/Makefile
+++ b/arch/sparc/Makefile
@@ -26,6 +26,7 @@ UTS_MACHINE    := sparc
 
 KBUILD_CFLAGS  += -m32 -mcpu=v8 -pipe -mno-fpu -fcall-used-g5 -fcall-used-g7
 KBUILD_AFLAGS  += -m32 -Wa,-Av8
+UAPICFLAGS     += -m32
 
 else
 #####
@@ -42,6 +43,7 @@ KBUILD_CFLAGS += -ffixed-g4 -ffixed-g5 -fcall-used-g7 -Wno-sign-compare
 KBUILD_CFLAGS += -Wa,--undeclared-regs
 KBUILD_CFLAGS += $(call cc-option,-mtune=ultrasparc3)
 KBUILD_AFLAGS += -m64 -mcpu=ultrasparc -Wa,--undeclared-regs
+UAPICFLAGS    += -m64
 
 ifeq ($(CONFIG_MCOUNT),y)
   KBUILD_CFLAGS += -pg
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 33f71b0..4f21420 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -50,6 +50,7 @@ ifeq ($(CONFIG_X86_32),y)
         biarch := $(call cc-option,-m32)
         KBUILD_AFLAGS += $(biarch)
         KBUILD_CFLAGS += $(biarch)
+        UAPICFLAGS    += $(biarch)
 
         KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
 
@@ -82,6 +83,7 @@ else
         biarch := -m64
         KBUILD_AFLAGS += -m64
         KBUILD_CFLAGS += -m64
+        UAPICFLAGS    += -m64
 
         # Don't autogenerate traditional x87, MMX or SSE instructions
         KBUILD_CFLAGS += -mno-mmx -mno-sse
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index bf3e677..5526769 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -64,6 +64,10 @@ ifneq ($(hostprogs-y)$(hostprogs-m),)
 include scripts/Makefile.host
 endif
 
+ifdef uapiprogs-y
+include scripts/Makefile.uapiprogs
+endif
+
 ifneq ($(KBUILD_SRC),)
 # Create output directory if not already present
 _dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))
diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean
index 686cb0d..aee43fa 100644
--- a/scripts/Makefile.clean
+++ b/scripts/Makefile.clean
@@ -40,10 +40,11 @@ subdir-ymn	:= $(addprefix $(obj)/,$(subdir-ymn))
 # build a list of files to remove, usually relative to the current
 # directory
 
-__clean-files	:= $(extra-y) $(always)                  \
-		   $(targets) $(clean-files)             \
-		   $(host-progs)                         \
-		   $(hostprogs-y) $(hostprogs-m) $(hostprogs-)
+__clean-files	:= $(extra-y) $(always)                        \
+		   $(targets) $(clean-files)                   \
+		   $(host-progs)                               \
+		   $(hostprogs-y) $(hostprogs-m) $(hostprogs-) \
+		   $(uapiprogs-y) $(uapiprogs-)
 
 __clean-files   := $(filter-out $(no-clean-files), $(__clean-files))
 
diff --git a/scripts/Makefile.uapiprogs b/scripts/Makefile.uapiprogs
new file mode 100644
index 0000000..63c09d0
--- /dev/null
+++ b/scripts/Makefile.uapiprogs
@@ -0,0 +1,63 @@
+# ==========================================================================
+# Building uapi binaries for ARCH on the host system using kernel
+# uapi header include files
+#
+# Sample syntax (see Documentation/kbuild/makefiles.txt for reference)
+# uapiprogs-y := hid-example
+# Will compile hid-example.c and create an executable named hid-example
+#
+# uapiprogs-y := bpf-fancy
+# bpf-fancy-y := bpf-fancy.o bpf-helper.o
+# Will compile bpf-fancy.c and bpf-helper.c, and then link the executable
+# bpf-fancy, based on bpf-fancy.o bpf-helper.o
+#
+
+__uapiprogs := $(sort $(uapiprogs-y))
+
+# Executables compiled from a single .c file
+uapi-csingle := $(foreach m,$(__uapiprogs),$(if $($(m)-y),,$(m)))
+
+# Executables linked based on several .o files
+uapi-cmulti := $(foreach m,$(__uapiprogs), $(if $($(m)-y),$(m)))
+
+# Object (.o) files compiled from .c files
+uapi-cobjs := $(sort $(foreach m,$(__uapiprogs),$($(m)-y)))
+
+# Add $(obj) prefix to all paths
+uapi-csingle := $(addprefix $(obj)/,$(uapi-csingle))
+uapi-cmulti  := $(addprefix $(obj)/,$(uapi-cmulti))
+uapi-cobjs   := $(addprefix $(obj)/,$(uapi-cobjs))
+
+# Options to uapicc.
+uapic_flags = -Wp,-MD,$(depfile) -isystem $(INSTALL_HDR_PATH)/include \
+              $(UAPICFLAGS) -Wall
+
+#####
+# Compile uapi programs on the build host
+
+# Create executable from a single .c file
+# uapi-csingle -> executable
+quiet_cmd_uapi-csingle = UAPICC  $@
+      cmd_uapi-csingle = $(CC) $(uapic_flags) -o $@ $<
+$(uapi-csingle): $(obj)/%: $(src)/%.c FORCE
+	$(call if_changed_dep,uapi-csingle)
+
+# Create .o file from a single .c file
+# uapi-cobjs -> .o
+quiet_cmd_uapi-cobjs	= UAPICC  $@
+      cmd_uapi-cobjs	= $(CC) $(uapic_flags) -c -o $@ $<
+$(uapi-cobjs): $(obj)/%.o: $(src)/%.c FORCE
+	$(call if_changed_dep,uapi-cobjs)
+
+# Link an executable based on list of .o files
+# uapi-cmulti -> executable
+quiet_cmd_uapi-cmulti	= UAPILD  $@
+      cmd_uapi-cmulti	= $(CC) -o $@ \
+			  $(addprefix $(obj)/,$($(@F)-y))
+$(uapi-cmulti): $(obj)/%: $(uapi-cobjs) FORCE
+	$(call if_changed,uapi-cmulti)
+
+# Clean support
+targets += $(uapi-csingle) $(uapi-cmulti) $(uapi-cobjs)
+always += $(uapi-csingle) $(uapi-cmulti)
+
-- 
1.9.3

[PATCH 2/6] samples: refactor Makefile

[Sam Ravnborg]

Use one line per module/program in Makefile.
This style is easier to read/extend.

Introduce inverse xmas style sorting.
This may prevent some merge conflicts in the future

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
---
 samples/Makefile | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/samples/Makefile b/samples/Makefile
index 1a60c62..7c08028 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,15 @@
 # Makefile for Linux samples code
+# Sort entries using inverse xmas style
+#
+# kernel modules
+obj-$(CONFIG_SAMPLES) += hw_breakpoint/
+obj-$(CONFIG_SAMPLES) += trace_events/
+obj-$(CONFIG_SAMPLES) += kprobes/
+obj-$(CONFIG_SAMPLES) += kobject/
+obj-$(CONFIG_SAMPLES) += kfifo/
+obj-$(CONFIG_SAMPLES) += rpmsg/
+obj-$(CONFIG_SAMPLES) += kdb/
 
-obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ \
-			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/
+# user space programs
+obj-$(CONFIG_SAMPLES) += seccomp/
+obj-$(CONFIG_SAMPLES) += hidraw/
-- 
1.9.3

Re: [PATCH 2/6] samples: refactor Makefile

[Randy Dunlap]

On 07/13/14 11:42, Sam Ravnborg wrote:
> Use one line per module/program in Makefile.
> This style is easier to read/extend.
> 
> Introduce inverse xmas style sorting.

google search couldn't tell me what that means and I cannot
deduce it from the new Makefile ordering (if there is some ordering).
Please explain.

Thanks.

> This may prevent some merge conflicts in the future
> 
> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
> ---
>  samples/Makefile | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/samples/Makefile b/samples/Makefile
> index 1a60c62..7c08028 100644
> --- a/samples/Makefile
> +++ b/samples/Makefile
> @@ -1,4 +1,15 @@
>  # Makefile for Linux samples code
> +# Sort entries using inverse xmas style
> +#
> +# kernel modules
> +obj-$(CONFIG_SAMPLES) += hw_breakpoint/
> +obj-$(CONFIG_SAMPLES) += trace_events/
> +obj-$(CONFIG_SAMPLES) += kprobes/
> +obj-$(CONFIG_SAMPLES) += kobject/
> +obj-$(CONFIG_SAMPLES) += kfifo/
> +obj-$(CONFIG_SAMPLES) += rpmsg/
> +obj-$(CONFIG_SAMPLES) += kdb/
>  
> -obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ \
> -			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/
> +# user space programs
> +obj-$(CONFIG_SAMPLES) += seccomp/
> +obj-$(CONFIG_SAMPLES) += hidraw/
> 


-- 
~Randy

Re: [PATCH 2/6] samples: refactor Makefile

[Sam Ravnborg]

Hi Randy - thanks for the feedback.

On Sun, Jul 13, 2014 at 12:25:33PM -0700, Randy Dunlap wrote:
> On 07/13/14 11:42, Sam Ravnborg wrote:
> > Use one line per module/program in Makefile.
> > This style is easier to read/extend.
> > 
> > Introduce inverse xmas style sorting.
> 
> google search couldn't tell me what that means and I cannot
> deduce it from the new Makefile ordering (if there is some ordering).
> Please explain.

Sort by length - with longest entry first. Like an xmas tree upside-down.
For entries with same lenght sort alphabetically.

Advocated in some places for includes and other places for local variables.

One recent reference is for example this:
http://marc.info/?l=linux-netdev&m=140510662905580&w=2

I will rephrase it like this:

# Sort entries using inverse xmas style:
# Longest entries first, alphabetically when legth is the same.

OK?
	Sam



> 
> Thanks.
> 
> > This may prevent some merge conflicts in the future
> > 
> > Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
> > ---
> >  samples/Makefile | 15 +++++++++++++--
> >  1 file changed, 13 insertions(+), 2 deletions(-)
> > 
> > diff --git a/samples/Makefile b/samples/Makefile
> > index 1a60c62..7c08028 100644
> > --- a/samples/Makefile
> > +++ b/samples/Makefile
> > @@ -1,4 +1,15 @@
> >  # Makefile for Linux samples code
> > +# Sort entries using inverse xmas style
> > +#
> > +# kernel modules
> > +obj-$(CONFIG_SAMPLES) += hw_breakpoint/
> > +obj-$(CONFIG_SAMPLES) += trace_events/
> > +obj-$(CONFIG_SAMPLES) += kprobes/
> > +obj-$(CONFIG_SAMPLES) += kobject/
> > +obj-$(CONFIG_SAMPLES) += kfifo/
> > +obj-$(CONFIG_SAMPLES) += rpmsg/
> > +obj-$(CONFIG_SAMPLES) += kdb/
> >  
> > -obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ \
> > -			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/
> > +# user space programs
> > +obj-$(CONFIG_SAMPLES) += seccomp/
> > +obj-$(CONFIG_SAMPLES) += hidraw/
> > 
> 
> 
> -- 
> ~Randy

Re: [PATCH 2/6] samples: refactor Makefile

[Randy Dunlap]

On 07/13/14 12:52, Sam Ravnborg wrote:
> Hi Randy - thanks for the feedback.
> 
> On Sun, Jul 13, 2014 at 12:25:33PM -0700, Randy Dunlap wrote:
>> On 07/13/14 11:42, Sam Ravnborg wrote:
>>> Use one line per module/program in Makefile.
>>> This style is easier to read/extend.
>>>
>>> Introduce inverse xmas style sorting.
>>
>> google search couldn't tell me what that means and I cannot
>> deduce it from the new Makefile ordering (if there is some ordering).
>> Please explain.
> 
> Sort by length - with longest entry first. Like an xmas tree upside-down.
> For entries with same lenght sort alphabetically.
> 
> Advocated in some places for includes and other places for local variables.
> 
> One recent reference is for example this:
> http://marc.info/?l=linux-netdev&m=140510662905580&w=2
> 
> I will rephrase it like this:
> 
> # Sort entries using inverse xmas style:
> # Longest entries first, alphabetically when legth is the same.

                                               length

> 
> OK?

Yes.  Thanks.

> 	Sam
> 
> 
> 
>>
>> Thanks.
>>
>>> This may prevent some merge conflicts in the future
>>>
>>> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
>>> ---
>>>  samples/Makefile | 15 +++++++++++++--
>>>  1 file changed, 13 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/samples/Makefile b/samples/Makefile
>>> index 1a60c62..7c08028 100644
>>> --- a/samples/Makefile
>>> +++ b/samples/Makefile
>>> @@ -1,4 +1,15 @@
>>>  # Makefile for Linux samples code
>>> +# Sort entries using inverse xmas style
>>> +#
>>> +# kernel modules
>>> +obj-$(CONFIG_SAMPLES) += hw_breakpoint/
>>> +obj-$(CONFIG_SAMPLES) += trace_events/
>>> +obj-$(CONFIG_SAMPLES) += kprobes/
>>> +obj-$(CONFIG_SAMPLES) += kobject/
>>> +obj-$(CONFIG_SAMPLES) += kfifo/
>>> +obj-$(CONFIG_SAMPLES) += rpmsg/
>>> +obj-$(CONFIG_SAMPLES) += kdb/
>>>  
>>> -obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ \
>>> -			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/
>>> +# user space programs
>>> +obj-$(CONFIG_SAMPLES) += seccomp/
>>> +obj-$(CONFIG_SAMPLES) += hidraw/


-- 
~Randy

Re: [PATCH 2/6] samples: refactor Makefile

[Stephen Rothwell]

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Hi Sam,

On Sun, 13 Jul 2014 21:52:36 +0200 Sam Ravnborg <sam@ravnborg.org> wrote:
>
> On Sun, Jul 13, 2014 at 12:25:33PM -0700, Randy Dunlap wrote:
> > On 07/13/14 11:42, Sam Ravnborg wrote:
> > > Use one line per module/program in Makefile.
> > > This style is easier to read/extend.
> > > 
> > > Introduce inverse xmas style sorting.
> > 
> > google search couldn't tell me what that means and I cannot
> > deduce it from the new Makefile ordering (if there is some ordering).
> > Please explain.
> 
> Sort by length - with longest entry first. Like an xmas tree upside-down.
> For entries with same lenght sort alphabetically.

If you are going to sort, just sort alphabetically ... this length
based sorting just means you have to search to find anything ... It
looks pretty, but that is about all.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au

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[PATCH 3/6] samples: use uapiprogs support for seccomp

[Sam Ravnborg]

Reduce complexity of seccomp Makefile by introducing use of uapiprogs support.
Build testet with i686 only.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
---
 samples/Makefile         |  2 +-
 samples/seccomp/Makefile | 48 ++----------------------------------------------
 2 files changed, 3 insertions(+), 47 deletions(-)

diff --git a/samples/Makefile b/samples/Makefile
index 7c08028..b4d7d66 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -11,5 +11,5 @@ obj-$(CONFIG_SAMPLES) += rpmsg/
 obj-$(CONFIG_SAMPLES) += kdb/
 
 # user space programs
-obj-$(CONFIG_SAMPLES) += seccomp/
+subdir-$(CONFIG_SAMPLES) += seccomp
 obj-$(CONFIG_SAMPLES) += hidraw/
diff --git a/samples/seccomp/Makefile b/samples/seccomp/Makefile
index 1b4e4b8..8f11cf4 100644
--- a/samples/seccomp/Makefile
+++ b/samples/seccomp/Makefile
@@ -1,48 +1,4 @@
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
+uapiprogs-$(CONFIG_SECCOMP_FILTER) := bpf-fancy dropper bpf-direct
 
-hostprogs-$(CONFIG_SECCOMP_FILTER) := bpf-fancy dropper bpf-direct
+bpf-fancy-y := bpf-fancy.o bpf-helper.o
 
-HOSTCFLAGS_bpf-fancy.o += -I$(objtree)/usr/include
-HOSTCFLAGS_bpf-fancy.o += -idirafter $(objtree)/include
-HOSTCFLAGS_bpf-helper.o += -I$(objtree)/usr/include
-HOSTCFLAGS_bpf-helper.o += -idirafter $(objtree)/include
-bpf-fancy-objs := bpf-fancy.o bpf-helper.o
-
-HOSTCFLAGS_dropper.o += -I$(objtree)/usr/include
-HOSTCFLAGS_dropper.o += -idirafter $(objtree)/include
-dropper-objs := dropper.o
-
-HOSTCFLAGS_bpf-direct.o += -I$(objtree)/usr/include
-HOSTCFLAGS_bpf-direct.o += -idirafter $(objtree)/include
-bpf-direct-objs := bpf-direct.o
-
-# Try to match the kernel target.
-ifndef CROSS_COMPILE
-ifndef CONFIG_64BIT
-
-# s390 has -m31 flag to build 31 bit binaries
-ifndef CONFIG_S390
-MFLAG = -m32
-else
-MFLAG = -m31
-endif
-
-HOSTCFLAGS_bpf-direct.o += $(MFLAG)
-HOSTCFLAGS_dropper.o += $(MFLAG)
-HOSTCFLAGS_bpf-helper.o += $(MFLAG)
-HOSTCFLAGS_bpf-fancy.o += $(MFLAG)
-HOSTLOADLIBES_bpf-direct += $(MFLAG)
-HOSTLOADLIBES_bpf-fancy += $(MFLAG)
-HOSTLOADLIBES_dropper += $(MFLAG)
-endif
-always := $(hostprogs-y)
-else
-# MIPS system calls are defined based on the -mabi that is passed
-# to the toolchain which may or may not be a valid option
-# for the host toolchain. So disable tests if target architecture
-# is MIPS but the host isn't.
-ifndef CONFIG_MIPS
-always := $(hostprogs-y)
-endif
-endif
-- 
1.9.3

Re: [PATCH 3/6] samples: use uapiprogs support for seccomp

[Masahiro Yamada]

Hi Sam,


On Sun, 13 Jul 2014 20:42:51 +0200
Sam Ravnborg <sam@ravnborg.org> wrote:

> Reduce complexity of seccomp Makefile by introducing use of uapiprogs support.
> Build testet with i686 only.

tested ?

(Ditto in 4/6)



> --- a/samples/seccomp/Makefile
> +++ b/samples/seccomp/Makefile
> @@ -1,48 +1,4 @@
> -# kbuild trick to avoid linker error. Can be omitted if a module is built.
> -obj- := dummy.o
> +uapiprogs-$(CONFIG_SECCOMP_FILTER) := bpf-fancy dropper bpf-direct
>  
> -hostprogs-$(CONFIG_SECCOMP_FILTER) := bpf-fancy dropper bpf-direct
> +bpf-fancy-y := bpf-fancy.o bpf-helper.o
>  
> -HOSTCFLAGS_bpf-fancy.o += -I$(objtree)/usr/include
> -HOSTCFLAGS_bpf-fancy.o += -idirafter $(objtree)/include
> -HOSTCFLAGS_bpf-helper.o += -I$(objtree)/usr/include
> -HOSTCFLAGS_bpf-helper.o += -idirafter $(objtree)/include
> -bpf-fancy-objs := bpf-fancy.o bpf-helper.o
> -



I am interested in this series.

Forgive me if I am asking a stupid question..


How can I build hostprogs for the same host as the kernel?
(I mean, how can I override $(HOSTCC) for cross-compiling ?)


Best Regards
Masahiro Yamada

Re: [PATCH 3/6] samples: use uapiprogs support for seccomp

[Sam Ravnborg]

On Wed, Jul 16, 2014 at 06:43:51PM +0900, Masahiro Yamada wrote:
> Hi Sam,
> 
> 
> On Sun, 13 Jul 2014 20:42:51 +0200
> Sam Ravnborg <sam@ravnborg.org> wrote:
> 
> > Reduce complexity of seccomp Makefile by introducing use of uapiprogs support.
> > Build testet with i686 only.
> 
> tested ?
> 
> (Ditto in 4/6)
Thanks - will fix.

> I am interested in this series.
> 
> Forgive me if I am asking a stupid question..
> 
> 
> How can I build hostprogs for the same host as the kernel?
> (I mean, how can I override $(HOSTCC) for cross-compiling ?)

One way to do this:

make ARCH=sparc CROSS_COMPILE=sparc-leon-linux-gnu- HOSTCC=sparc-leon-linux-gnu-gcc

Notice that I override HOSTCC as part of the make comand line.
This allows me to override the "=" assignment in the top-level Makefile.

But then my build breaks as fixdep do not run on my host.

If you in general want to build a binary for the target then uapiprogs come in handy.
Only caveat here is that you will be using the exported kernel headers.

	Sam

Re: [PATCH 3/6] samples: use uapiprogs support for seccomp

[Masahiro Yamada]

On Wed, 16 Jul 2014 12:31:21 +0200
Sam Ravnborg <sam@ravnborg.org> wrote:

> > How can I build hostprogs for the same host as the kernel?
> > (I mean, how can I override $(HOSTCC) for cross-compiling ?)
> 
> One way to do this:
> 
> make ARCH=sparc CROSS_COMPILE=sparc-leon-linux-gnu- HOSTCC=sparc-leon-linux-gnu-gcc
> 
> Notice that I override HOSTCC as part of the make comand line.
> This allows me to override the "=" assignment in the top-level Makefile.
> 
> But then my build breaks as fixdep do not run on my host.
> 
> If you in general want to build a binary for the target then uapiprogs come in handy.
> Only caveat here is that you will be using the exported kernel headers.
> 

Thanks for explaining this. It is clearer to me now.

At first I thought this patch was a clean-up,
but it is indeed a big improvement.
Thanks!



Best Regards
Masahiro Yamada

[PATCH 4/6] samples: use uapiprogs support for hidraw

[Sam Ravnborg]

Reduce complexity of hidraw Makefile by introducing use of uapiprogs support.
Build testet with i386 + sparc32.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: David Herrmann <dh.herrmann@googlemail.com>
Cc: Jiri Kosina <jkosina@suse.cz>

---
 samples/Makefile        |  2 +-
 samples/hidraw/Makefile | 11 +----------
 2 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/samples/Makefile b/samples/Makefile
index b4d7d66..8fc6c45 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -12,4 +12,4 @@ obj-$(CONFIG_SAMPLES) += kdb/
 
 # user space programs
 subdir-$(CONFIG_SAMPLES) += seccomp
-obj-$(CONFIG_SAMPLES) += hidraw/
+subdir-$(CONFIG_SAMPLES) += hidraw
diff --git a/samples/hidraw/Makefile b/samples/hidraw/Makefile
index 382eeae..c2d2544 100644
--- a/samples/hidraw/Makefile
+++ b/samples/hidraw/Makefile
@@ -1,10 +1 @@
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
-# List of programs to build
-hostprogs-y := hid-example
-
-# Tell kbuild to always build the programs
-always := $(hostprogs-y)
-
-HOSTCFLAGS_hid-example.o += -I$(objtree)/usr/include
+uapiprogs-y := hid-example
-- 
1.9.3

[PATCH 5/6] samples: fix warnings in uhid-example

[Sam Ravnborg]

Fix following warnings seen when building using i686:
uhid-example.c: In function ‘uhid_write’:
uhid-example.c:168:4: warning: format ‘%ld’ expects argument of type ‘long int’, but argument 3 has type ‘ssize_t’ [-Wformat=]
uhid-example.c:168:4: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 4 has type ‘unsigned int’ [-Wformat=]
uhid-example.c: In function ‘event’:
uhid-example.c:239:4: warning: format ‘%ld’ expects argument of type ‘long int’, but argument 3 has type ‘ssize_t’ [-Wformat=]
uhid-example.c:239:4: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 4 has type ‘unsigned int’ [-Wformat=]

Use "%xd" for arguments of type size_t to fix the warnings.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: David Herrmann <dh.herrmann@googlemail.com>
Cc: Jiri Kosina <jkosina@suse.cz>
---
 samples/uhid/uhid-example.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/samples/uhid/uhid-example.c b/samples/uhid/uhid-example.c
index 7d58a4b..f25a5ef 100644
--- a/samples/uhid/uhid-example.c
+++ b/samples/uhid/uhid-example.c
@@ -164,7 +164,7 @@ static int uhid_write(int fd, const struct uhid_event *ev)
 		fprintf(stderr, "Cannot write to uhid: %m\n");
 		return -errno;
 	} else if (ret != sizeof(*ev)) {
-		fprintf(stderr, "Wrong size written to uhid: %ld != %lu\n",
+		fprintf(stderr, "Wrong size written to uhid: %zd != %zd\n",
 			ret, sizeof(ev));
 		return -EFAULT;
 	} else {
@@ -235,7 +235,7 @@ static int event(int fd)
 		fprintf(stderr, "Cannot read uhid-cdev: %m\n");
 		return -errno;
 	} else if (ret != sizeof(ev)) {
-		fprintf(stderr, "Invalid size read from uhid-dev: %ld != %lu\n",
+		fprintf(stderr, "Invalid size read from uhid-dev: %zd != %zd\n",
 			ret, sizeof(ev));
 		return -EFAULT;
 	}
-- 
1.9.3

[PATCH 6/6] samples: use uapiprogs support for uhid

[Sam Ravnborg]

uhid was not included in the regular builds as it was not wired
up in samples/Makefile.

Fix build on sparc32 by defining __USE_GNU to get visibility to O_CLOEXEC.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Jiri Kosina <jkosina@suse.cz>
---
 samples/Makefile            |  1 +
 samples/uhid/Makefile       | 11 +----------
 samples/uhid/uhid-example.c |  5 ++++-
 3 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/samples/Makefile b/samples/Makefile
index 8fc6c45..29a09bd 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_SAMPLES) += kdb/
 # user space programs
 subdir-$(CONFIG_SAMPLES) += seccomp
 subdir-$(CONFIG_SAMPLES) += hidraw
+subdir-$(CONFIG_SAMPLES) += uhid
diff --git a/samples/uhid/Makefile b/samples/uhid/Makefile
index c95a696..75ff2bb 100644
--- a/samples/uhid/Makefile
+++ b/samples/uhid/Makefile
@@ -1,10 +1 @@
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
-# List of programs to build
-hostprogs-y := uhid-example
-
-# Tell kbuild to always build the programs
-always := $(hostprogs-y)
-
-HOSTCFLAGS_uhid-example.o += -I$(objtree)/usr/include
+uapiprogs-y := uhid-example
diff --git a/samples/uhid/uhid-example.c b/samples/uhid/uhid-example.c
index f25a5ef..e4379c8 100644
--- a/samples/uhid/uhid-example.c
+++ b/samples/uhid/uhid-example.c
@@ -37,7 +37,6 @@
  */
 
 #include <errno.h>
-#include <fcntl.h>
 #include <poll.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -45,6 +44,10 @@
 #include <string.h>
 #include <termios.h>
 #include <unistd.h>
+
+#define __USE_GNU
+#include <fcntl.h>
+
 #include <linux/uhid.h>
 
 /*
-- 
1.9.3

Re: [PATCH 1/6] kbuild: add support for building userspace api programs

[Randy Dunlap]

Hi Sam,

On 07/13/14 11:42, Sam Ravnborg wrote:
> 
> diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
> index c600e2f..713ea10 100644
> --- a/Documentation/kbuild/makefiles.txt
> +++ b/Documentation/kbuild/makefiles.txt
> @@ -761,7 +763,43 @@ Both possibilities are described in the following.
>  	like hostprogs-y. But only hostprogs-y is recommended to be used
>  	when no CONFIG symbols are involved.
>  
> -=== 5 Kbuild clean infrastructure
> +=== 5 Samples support (uapiprogs-y)
> +
> +Kbuild support building sample modules and sample binaries.

          supports

> +To build sample modules the existing infrastructure is used, but
> +to build sample binaries kbuild adds dedicated suppport.
> +
> +The sample binaries are build for the same host and bit-size as the kernel.

                           built

> +
> +The samples may demonstrate facilities not yet available
> +in the installed libc therefore they are build so they include

                    libc;                   built

> +headers from the exported uapi headers before the libc headers
> +are searched.
> +
> +The sample binaries are usually placed in sub-directories
> +below samples/ and specified in samples/Makefile.
> +The directories containing sample binaries are listed using
> +subdir-y - usually like this: subdir-$(CONFIG_SAMPLES) += dir
> +
> +The individual binaries may be defined as single .c file per binary
> +or several .c files for a single binary.
> +See the following examples.
> +
> +	Example:
> +		# samples/hid/Makefile
> +		uapiprogs-y := hid-example
> +
> +	This will compile hid-example.c and create an executable named hid-example.
> +
> +	Example:
> +		# samples/seccomp/Makefile
> +		uapiprogs-y := bpf-fancy
> +		bpf-fancy-y := bpf-fancy.o bpf-helper.o
> +
> +This will compile bpf-fancy.c and bpf-helper.c, and then link the executable
> +bpf-fancy, based on bpf-fancy.o bpf-helper.o.
> +
> +=== 6 Kbuild clean infrastructure
>  
>  "make clean" deletes most generated files in the obj tree where the kernel
>  is compiled. This includes generated files such as host programs.


-- 
~Randy

Re: [PATCH 1/6] kbuild: add support for building userspace api programs

[Sam Ravnborg]

Hi Randy.

Thanks, I will include all corrections in v3.

	Sam

Re: [PATCH v2 0/6] kbuild: use target compiler for user binaries in samples/

[Stephen Rothwell]

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Hi Sam,

On Sun, 13 Jul 2014 20:36:37 +0200 Sam Ravnborg <sam@ravnborg.org> wrote:
>
> NOTE: This will likely break the build if the toolchain used do
> not include a libc. Let's see how much noise this creates.

Then I will drop them from linux-next.  Until someone supplies lots of
cross compilers with libc support, the samples can not (must not) be
built by default.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au

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Re: [PATCH v2 0/6] kbuild: use target compiler for user binaries in samples/

[Stephen Rothwell]

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Hi Sam,

On Mon, 14 Jul 2014 10:29:36 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> 
> On Sun, 13 Jul 2014 20:36:37 +0200 Sam Ravnborg <sam@ravnborg.org> wrote:
> >
> > NOTE: This will likely break the build if the toolchain used do
> > not include a libc. Let's see how much noise this creates.
> 
> Then I will drop them from linux-next.  Until someone supplies lots of
> cross compilers with libc support, the samples can not (must not) be
> built by default.

Just to be clear: for my current build infrastructure, this means
powerpc and x86_64 hosted cross compilers.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au

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Re: [PATCH v2 0/6] kbuild: use target compiler for user binaries in samples/

[Michal Marek]

On 2014-07-14 02:33, Stephen Rothwell wrote:
> Hi Sam,
> 
> On Mon, 14 Jul 2014 10:29:36 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>>
>> On Sun, 13 Jul 2014 20:36:37 +0200 Sam Ravnborg <sam@ravnborg.org> wrote:
>>>
>>> NOTE: This will likely break the build if the toolchain used do
>>> not include a libc. Let's see how much noise this creates.
>>
>> Then I will drop them from linux-next.  Until someone supplies lots of
>> cross compilers with libc support, the samples can not (must not) be
>> built by default.
> 
> Just to be clear: for my current build infrastructure, this means
> powerpc and x86_64 hosted cross compilers.

So we basically can have zero, one or both of
A) target toolchain with libc support
B) host toolchain with recent enough kernel headers

Just can idea - in case we have B, but not A, would it make sense to
build $(uapiprogs-y) with the host compiler, but without the
-Iusr/include flag? The question is whether to add a kconfig knob for
this, or some automatic detection for libc support of the target
toolchain. I'll come up with a patch later.

Michal

Re: [PATCH v2 0/6] kbuild: use target compiler for user binaries in samples/

[Michal Marek]

On Thu, Jul 17, 2014 at 05:22:18PM +0200, Michal Marek wrote:
> On 2014-07-14 02:33, Stephen Rothwell wrote:
> > Hi Sam,
> > 
> > On Mon, 14 Jul 2014 10:29:36 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> >>
> >> On Sun, 13 Jul 2014 20:36:37 +0200 Sam Ravnborg <sam@ravnborg.org> wrote:
> >>>
> >>> NOTE: This will likely break the build if the toolchain used do
> >>> not include a libc. Let's see how much noise this creates.
> >>
> >> Then I will drop them from linux-next.  Until someone supplies lots of
> >> cross compilers with libc support, the samples can not (must not) be
> >> built by default.
> > 
> > Just to be clear: for my current build infrastructure, this means
> > powerpc and x86_64 hosted cross compilers.
> 
> So we basically can have zero, one or both of
> A) target toolchain with libc support
> B) host toolchain with recent enough kernel headers
> 
> Just can idea - in case we have B, but not A, would it make sense to
> build $(uapiprogs-y) with the host compiler, but without the
> -Iusr/include flag?

Actually, we can build with the host compiler against the exported
headers, these just need to be exported for the right architecture.
How about the following patch (applies on top of 1/6 of
this series)? It creates a usr/host/include tree with headers for the
host architecture and builds the uapiprogs with the host compiler. This
should build in all scenarios that work today. The only downside is that
when cross-compiling, the sample binaries continue to be somewhat
impractical. But it is not _that_ difficult to build them by hand,
provided one has a complete cross-compiling setup.

Michal

diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 6b691d3b..6466704 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -233,8 +233,3 @@ KBUILD_VMLINUX_MAIN
 All object files for the main part of vmlinux.
 KBUILD_VMLINUX_INIT and KBUILD_VMLINUX_MAIN together specify
 all the object files used to link vmlinux.
-
-UAPICFLAGS
---------------------------------------------------
-Arch specific flags used when building sample binaries.
-This is usually the machine size (32 versus 64 bit).
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 2c6d53b..163d5dd 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -746,7 +746,7 @@ Kbuild support building sample modules and sample binaries.
 To build sample modules the existing infrastructure is used, but
 to build sample binaries kbuild adds dedicated suppport.
 
-The sample binaries are build for the same host and bit-size as the kernel.
+The sample binaries are build for the architecture of the build host.
 
 The samples may demonstrate facilities not yet available
 in the installed libc therefore they are build so they include
diff --git a/Makefile b/Makefile
index 9f654a4..66073f2 100644
--- a/Makefile
+++ b/Makefile
@@ -968,11 +968,13 @@ prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
 
 archprepare: archheaders archscripts prepare1 scripts_basic
 
-# To build userspace samples the uapi headers needs to be exported
+# To build userspace samples the uapi headers need to be exported for
+# the host architecture
 prepare0: archprepare FORCE
 	$(Q)$(MAKE) $(build)=.
 ifdef CONFIG_SAMPLES
-	$(Q)$(MAKE) KBUILD_SRC= headers_install
+	$(MAKE) KBUILD_SRC= ARCH=$(SUBARCH) \
+		INSTALL_HDR_PATH=usr/host headers_install
 endif
 
 # All the preparing..
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 4b32933..874e6d6 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -18,7 +18,6 @@ LD_BFD		:= elf32-s390
 LDFLAGS		:= -m elf_s390
 KBUILD_CFLAGS	+= -m31
 KBUILD_AFLAGS	+= -m31
-UAPICFLAGS	+= -m31
 UTS_MACHINE	:= s390
 STACK_SIZE	:= 8192
 CHECKFLAGS	+= -D__s390__ -msize-long
@@ -29,7 +28,6 @@ KBUILD_AFLAGS_MODULE += -fPIC
 KBUILD_CFLAGS_MODULE += -fPIC
 KBUILD_CFLAGS	+= -m64
 KBUILD_AFLAGS	+= -m64
-UAPICFLAGS	+= -m64
 UTS_MACHINE	:= s390x
 STACK_SIZE	:= 16384
 CHECKFLAGS	+= -D__s390__ -D__s390x__
diff --git a/arch/sparc/Makefile b/arch/sparc/Makefile
index fc0dcf1..eaee146 100644
--- a/arch/sparc/Makefile
+++ b/arch/sparc/Makefile
@@ -26,7 +26,6 @@ UTS_MACHINE    := sparc
 
 KBUILD_CFLAGS  += -m32 -mcpu=v8 -pipe -mno-fpu -fcall-used-g5 -fcall-used-g7
 KBUILD_AFLAGS  += -m32 -Wa,-Av8
-UAPICFLAGS     += -m32
 
 else
 #####
@@ -43,7 +42,6 @@ KBUILD_CFLAGS += -ffixed-g4 -ffixed-g5 -fcall-used-g7 -Wno-sign-compare
 KBUILD_CFLAGS += -Wa,--undeclared-regs
 KBUILD_CFLAGS += $(call cc-option,-mtune=ultrasparc3)
 KBUILD_AFLAGS += -m64 -mcpu=ultrasparc -Wa,--undeclared-regs
-UAPICFLAGS    += -m64
 
 ifeq ($(CONFIG_MCOUNT),y)
   KBUILD_CFLAGS += -pg
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index add7271..c1aa368 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -47,7 +47,6 @@ ifeq ($(CONFIG_X86_32),y)
         biarch := $(call cc-option,-m32)
         KBUILD_AFLAGS += $(biarch)
         KBUILD_CFLAGS += $(biarch)
-        UAPICFLAGS    += $(biarch)
 
         KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
 
@@ -80,7 +79,6 @@ else
         biarch := -m64
         KBUILD_AFLAGS += -m64
         KBUILD_CFLAGS += -m64
-        UAPICFLAGS    += -m64
 
         # Don't autogenerate traditional x87, MMX or SSE instructions
         KBUILD_CFLAGS += -mno-mmx -mno-sse
diff --git a/scripts/Makefile.uapiprogs b/scripts/Makefile.uapiprogs
index 63c09d0..c88a0cc 100644
--- a/scripts/Makefile.uapiprogs
+++ b/scripts/Makefile.uapiprogs
@@ -29,8 +29,7 @@ uapi-cmulti  := $(addprefix $(obj)/,$(uapi-cmulti))
 uapi-cobjs   := $(addprefix $(obj)/,$(uapi-cobjs))
 
 # Options to uapicc.
-uapic_flags = -Wp,-MD,$(depfile) -isystem $(INSTALL_HDR_PATH)/include \
-              $(UAPICFLAGS) -Wall
+uapic_flags = -Wp,-MD,$(depfile) -isystem usr/host/include $(HOSTCFLAGS)
 
 #####
 # Compile uapi programs on the build host
@@ -38,21 +37,21 @@ uapic_flags = -Wp,-MD,$(depfile) -isystem $(INSTALL_HDR_PATH)/include \
 # Create executable from a single .c file
 # uapi-csingle -> executable
 quiet_cmd_uapi-csingle = UAPICC  $@
-      cmd_uapi-csingle = $(CC) $(uapic_flags) -o $@ $<
+      cmd_uapi-csingle = $(HOSTCC) $(uapic_flags) -o $@ $<
 $(uapi-csingle): $(obj)/%: $(src)/%.c FORCE
 	$(call if_changed_dep,uapi-csingle)
 
 # Create .o file from a single .c file
 # uapi-cobjs -> .o
 quiet_cmd_uapi-cobjs	= UAPICC  $@
-      cmd_uapi-cobjs	= $(CC) $(uapic_flags) -c -o $@ $<
+      cmd_uapi-cobjs	= $(HOSTCC) $(uapic_flags) -c -o $@ $<
 $(uapi-cobjs): $(obj)/%.o: $(src)/%.c FORCE
 	$(call if_changed_dep,uapi-cobjs)
 
 # Link an executable based on list of .o files
 # uapi-cmulti -> executable
 quiet_cmd_uapi-cmulti	= UAPILD  $@
-      cmd_uapi-cmulti	= $(CC) -o $@ \
+      cmd_uapi-cmulti	= $(HOSTCC) -o $@ \
 			  $(addprefix $(obj)/,$($(@F)-y))
 $(uapi-cmulti): $(obj)/%: $(uapi-cobjs) FORCE
 	$(call if_changed,uapi-cmulti)