From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752094AbdJFNVk (ORCPT ); Fri, 6 Oct 2017 09:21:40 -0400 Received: from foss.arm.com ([217.140.101.70]:59854 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751827AbdJFNVj (ORCPT ); Fri, 6 Oct 2017 09:21:39 -0400 Date: Fri, 6 Oct 2017 14:21:39 +0100 From: Will Deacon To: kbuild test robot Cc: kbuild-all@01.org, linux-kernel@vger.kernel.org, "Paul E. McKenney" Subject: Re: [rcu:dev.2017.10.05a 32/34] include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' Message-ID: <20171006132139.GA11387@arm.com> References: <201710060738.Yjubqqja%fengguang.wu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201710060738.Yjubqqja%fengguang.wu@intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Paul, On Fri, Oct 06, 2017 at 07:18:41AM +0800, kbuild test robot wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2017.10.05a > head: 39ae2675aa536e6ef9d334fe9097d1e2c6b25fbc > commit: 7e3675cc18bbf4d84f60bfc02ff563ae3764ad35 [32/34] locking/barriers: Kill lockless_dereference > config: h8300-h8300h-sim_defconfig (attached as .config) > compiler: h8300-linux-gcc (GCC) 6.2.0 > reproduce: > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > chmod +x ~/bin/make.cross > git checkout 7e3675cc18bbf4d84f60bfc02ff563ae3764ad35 > # save the attached .config to linux build tree > make.cross ARCH=h8300 > > All error/warnings (new ones prefixed by >>): > > In file included from include/uapi/linux/stddef.h:1:0, > from include/linux/stddef.h:4, > from arch/h8300/kernel/asm-offsets.c:11: > include/linux/list.h: In function 'list_empty': > >> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration] > smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ > ^ > include/linux/compiler.h:346:22: note: in expansion of macro '__READ_ONCE' > #define READ_ONCE(x) __READ_ONCE(x, 1) > ^~~~~~~~~~~ > >> include/linux/list.h:202:9: note: in expansion of macro 'READ_ONCE' > return READ_ONCE(head->next) == head; > ^~~~~~~~~ > cc1: some warnings being treated as errors > make[2]: *** [arch/h8300/kernel/asm-offsets.s] Error 1 > make[2]: Target '__build' not remade because of errors. > make[1]: *** [prepare0] Error 2 > make[1]: Target 'prepare' not remade because of errors. > make: *** [sub-make] Error 2 Ok, I dug into this and the problem is as follows: arch/h8300/kernel/asm-offsets.c includes linux/stddef.h for offsetof linux/stddef.h includes uapi/linux/stddef.h uapi/linux/stddef.h includes linux/compiler.h arch/h8300/kernel/asm-offsets.c also includes linux/sched.h for task_struct linux/sched.h includes linux/pid.h linux/pid.h includes linux/rculist.h linux/rculist.h includes linux/list.h linux/list.h then tries to instantiate some static inline functions that use READ_ONCE (e.g. list_empty), but nobody has included asm/barrier.h so the build fails. Ideally, we'd just include in linux/compiler.h (since lockless_dereference uses smp_read_barrier_depends in mainline today), but it's not quite that simple because compiler.h is also used by linux/types.h, so we don't even have a definition for "bool" at this stage! The best fix I could come up with involves splitting compiler.h into two headers: one for the type annotations and definitions, and the other for macros such as READ_ONCE. Patch below. Note that even with this change I'm unable to build h8300. The assembler chokes on a bunch of unrelated errors and the compiler eventually ICEs. Will --->8 >>From c3af54475c5be8789aa54823e56afcfb1b5b83da Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 6 Oct 2017 13:50:14 +0100 Subject: [PATCH] linux/compiler.h: Split into compiler.h and compiler-types.h linux/compiler.h is included indirectly by linux/types.h via uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h -> uapi/linux/stddef.h and is needed to provide a proper definition of offsetof. Unfortunately, compiler.h requires a definition of smp_read_barrier_depends() for defining READ_ONCE, which means that all users of READ_ONCE need to include asm/barrier.h to avoid splats such as: In file included from include/uapi/linux/stddef.h:1:0, from include/linux/stddef.h:4, from arch/h8300/kernel/asm-offsets.c:11: include/linux/list.h: In function 'list_empty': >> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration] smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ ^ A better alternative is to include asm/barrier.h in linux/compiler.h, but this requires a type definition for "bool" on some architectures (e.g. x86), which is defined later by linux/types.h. Type "bool" is also used directly in linux/compiler.h, so the whole thing is pretty fragile. This patch splits compiler.h in two: compiler-types.h contains type annotations, definitions and the compiler-specific parts, whereas compiler.h #includes compiler-types.h and additionally defines macros such as {READ,WRITE.ACCESS}_ONCE. uapi/linux/stddef.h is then moved over to include linux/compiler-types.h, which fixes the build. Reported-by: kbuild test robot Signed-off-by: Will Deacon --- include/linux/compiler-clang.h | 2 +- include/linux/compiler-gcc.h | 2 +- include/linux/compiler-intel.h | 2 +- include/linux/compiler-types.h | 274 +++++++++++++++++++++++++++++++++++++++++ include/linux/compiler.h | 265 +-------------------------------------- include/uapi/linux/stddef.h | 2 +- scripts/headers_install.sh | 2 +- 7 files changed, 282 insertions(+), 267 deletions(-) create mode 100644 include/linux/compiler-types.h diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index de179993e039..5947a3e6c0e6 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -1,4 +1,4 @@ -#ifndef __LINUX_COMPILER_H +#ifndef __LINUX_COMPILER_TYPES_H #error "Please don't include directly, include instead." #endif diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 16d41de92ee3..ce8e965646ef 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -1,4 +1,4 @@ -#ifndef __LINUX_COMPILER_H +#ifndef __LINUX_COMPILER_TYPES_H #error "Please don't include directly, include instead." #endif diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h index d4c71132d07f..e438ac89c692 100644 --- a/include/linux/compiler-intel.h +++ b/include/linux/compiler-intel.h @@ -1,4 +1,4 @@ -#ifndef __LINUX_COMPILER_H +#ifndef __LINUX_COMPILER_TYPES_H #error "Please don't include directly, include instead." #endif diff --git a/include/linux/compiler-types.h b/include/linux/compiler-types.h new file mode 100644 index 000000000000..6b79a9bba9a7 --- /dev/null +++ b/include/linux/compiler-types.h @@ -0,0 +1,274 @@ +#ifndef __LINUX_COMPILER_TYPES_H +#define __LINUX_COMPILER_TYPES_H + +#ifndef __ASSEMBLY__ + +#ifdef __CHECKER__ +# define __user __attribute__((noderef, address_space(1))) +# define __kernel __attribute__((address_space(0))) +# define __safe __attribute__((safe)) +# define __force __attribute__((force)) +# define __nocast __attribute__((nocast)) +# define __iomem __attribute__((noderef, address_space(2))) +# define __must_hold(x) __attribute__((context(x,1,1))) +# define __acquires(x) __attribute__((context(x,0,1))) +# define __releases(x) __attribute__((context(x,1,0))) +# define __acquire(x) __context__(x,1) +# define __release(x) __context__(x,-1) +# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0) +# define __percpu __attribute__((noderef, address_space(3))) +# define __rcu __attribute__((noderef, address_space(4))) +# define __private __attribute__((noderef)) +extern void __chk_user_ptr(const volatile void __user *); +extern void __chk_io_ptr(const volatile void __iomem *); +# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member)) +#else /* __CHECKER__ */ +# ifdef STRUCTLEAK_PLUGIN +# define __user __attribute__((user)) +# else +# define __user +# endif +# define __kernel +# define __safe +# define __force +# define __nocast +# define __iomem +# define __chk_user_ptr(x) (void)0 +# define __chk_io_ptr(x) (void)0 +# define __builtin_warning(x, y...) (1) +# define __must_hold(x) +# define __acquires(x) +# define __releases(x) +# define __acquire(x) (void)0 +# define __release(x) (void)0 +# define __cond_lock(x,c) (c) +# define __percpu +# define __rcu +# define __private +# define ACCESS_PRIVATE(p, member) ((p)->member) +#endif /* __CHECKER__ */ + +/* Indirect macros required for expanded argument pasting, eg. __LINE__. */ +#define ___PASTE(a,b) a##b +#define __PASTE(a,b) ___PASTE(a,b) + +#ifdef __KERNEL__ + +#ifdef __GNUC__ +#include +#endif + +#if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) +#define notrace __attribute__((hotpatch(0,0))) +#else +#define notrace __attribute__((no_instrument_function)) +#endif + +/* Intel compiler defines __GNUC__. So we will overwrite implementations + * coming from above header files here + */ +#ifdef __INTEL_COMPILER +# include +#endif + +/* Clang compiler defines __GNUC__. So we will overwrite implementations + * coming from above header files here + */ +#ifdef __clang__ +#include +#endif + +/* + * Generic compiler-dependent macros required for kernel + * build go below this comment. Actual compiler/compiler version + * specific implementations come from the above header files + */ + +struct ftrace_branch_data { + const char *func; + const char *file; + unsigned line; + union { + struct { + unsigned long correct; + unsigned long incorrect; + }; + struct { + unsigned long miss; + unsigned long hit; + }; + unsigned long miss_hit[2]; + }; +}; + +struct ftrace_likely_data { + struct ftrace_branch_data data; + unsigned long constant; +}; + +#endif /* __KERNEL__ */ + +#endif /* __ASSEMBLY__ */ + +#ifdef __KERNEL__ +/* + * Allow us to mark functions as 'deprecated' and have gcc emit a nice + * warning for each use, in hopes of speeding the functions removal. + * Usage is: + * int __deprecated foo(void) + */ +#ifndef __deprecated +# define __deprecated /* unimplemented */ +#endif + +#ifdef MODULE +#define __deprecated_for_modules __deprecated +#else +#define __deprecated_for_modules +#endif + +#ifndef __must_check +#define __must_check +#endif + +#ifndef CONFIG_ENABLE_MUST_CHECK +#undef __must_check +#define __must_check +#endif +#ifndef CONFIG_ENABLE_WARN_DEPRECATED +#undef __deprecated +#undef __deprecated_for_modules +#define __deprecated +#define __deprecated_for_modules +#endif + +#ifndef __malloc +#define __malloc +#endif + +/* + * Allow us to avoid 'defined but not used' warnings on functions and data, + * as well as force them to be emitted to the assembly file. + * + * As of gcc 3.4, static functions that are not marked with attribute((used)) + * may be elided from the assembly file. As of gcc 3.4, static data not so + * marked will not be elided, but this may change in a future gcc version. + * + * NOTE: Because distributions shipped with a backported unit-at-a-time + * compiler in gcc 3.3, we must define __used to be __attribute__((used)) + * for gcc >=3.3 instead of 3.4. + * + * In prior versions of gcc, such functions and data would be emitted, but + * would be warned about except with attribute((unused)). + * + * Mark functions that are referenced only in inline assembly as __used so + * the code is emitted even though it appears to be unreferenced. + */ +#ifndef __used +# define __used /* unimplemented */ +#endif + +#ifndef __maybe_unused +# define __maybe_unused /* unimplemented */ +#endif + +#ifndef __always_unused +# define __always_unused /* unimplemented */ +#endif + +#ifndef noinline +#define noinline +#endif + +/* + * Rather then using noinline to prevent stack consumption, use + * noinline_for_stack instead. For documentation reasons. + */ +#define noinline_for_stack noinline + +#ifndef __always_inline +#define __always_inline inline +#endif + +#endif /* __KERNEL__ */ + +/* + * From the GCC manual: + * + * Many functions do not examine any values except their arguments, + * and have no effects except the return value. Basically this is + * just slightly more strict class than the `pure' attribute above, + * since function is not allowed to read global memory. + * + * Note that a function that has pointer arguments and examines the + * data pointed to must _not_ be declared `const'. Likewise, a + * function that calls a non-`const' function usually must not be + * `const'. It does not make sense for a `const' function to return + * `void'. + */ +#ifndef __attribute_const__ +# define __attribute_const__ /* unimplemented */ +#endif + +#ifndef __designated_init +# define __designated_init +#endif + +#ifndef __latent_entropy +# define __latent_entropy +#endif + +#ifndef __randomize_layout +# define __randomize_layout __designated_init +#endif + +#ifndef __no_randomize_layout +# define __no_randomize_layout +#endif + +#ifndef randomized_struct_fields_start +# define randomized_struct_fields_start +# define randomized_struct_fields_end +#endif + +/* + * Tell gcc if a function is cold. The compiler will assume any path + * directly leading to the call is unlikely. + */ + +#ifndef __cold +#define __cold +#endif + +/* Simple shorthand for a section definition */ +#ifndef __section +# define __section(S) __attribute__ ((__section__(#S))) +#endif + +#ifndef __visible +#define __visible +#endif + +#ifndef __nostackprotector +# define __nostackprotector +#endif + +/* + * Assume alignment of return value. + */ +#ifndef __assume_aligned +#define __assume_aligned(a, ...) +#endif + + +/* Are two types/vars the same type (ignoring qualifiers)? */ +#ifndef __same_type +# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) +#endif + +/* Is this type a native word size -- useful for atomic operations */ +#ifndef __native_word +# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) +#endif + +#endif /* __LINUX_COMPILER_TYPES_H */ diff --git a/include/linux/compiler.h b/include/linux/compiler.h index f260ff39f90f..4517662f128c 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -1,111 +1,12 @@ #ifndef __LINUX_COMPILER_H #define __LINUX_COMPILER_H -#ifndef __ASSEMBLY__ +#include -#ifdef __CHECKER__ -# define __user __attribute__((noderef, address_space(1))) -# define __kernel __attribute__((address_space(0))) -# define __safe __attribute__((safe)) -# define __force __attribute__((force)) -# define __nocast __attribute__((nocast)) -# define __iomem __attribute__((noderef, address_space(2))) -# define __must_hold(x) __attribute__((context(x,1,1))) -# define __acquires(x) __attribute__((context(x,0,1))) -# define __releases(x) __attribute__((context(x,1,0))) -# define __acquire(x) __context__(x,1) -# define __release(x) __context__(x,-1) -# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0) -# define __percpu __attribute__((noderef, address_space(3))) -# define __rcu __attribute__((noderef, address_space(4))) -# define __private __attribute__((noderef)) -extern void __chk_user_ptr(const volatile void __user *); -extern void __chk_io_ptr(const volatile void __iomem *); -# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member)) -#else /* __CHECKER__ */ -# ifdef STRUCTLEAK_PLUGIN -# define __user __attribute__((user)) -# else -# define __user -# endif -# define __kernel -# define __safe -# define __force -# define __nocast -# define __iomem -# define __chk_user_ptr(x) (void)0 -# define __chk_io_ptr(x) (void)0 -# define __builtin_warning(x, y...) (1) -# define __must_hold(x) -# define __acquires(x) -# define __releases(x) -# define __acquire(x) (void)0 -# define __release(x) (void)0 -# define __cond_lock(x,c) (c) -# define __percpu -# define __rcu -# define __private -# define ACCESS_PRIVATE(p, member) ((p)->member) -#endif /* __CHECKER__ */ - -/* Indirect macros required for expanded argument pasting, eg. __LINE__. */ -#define ___PASTE(a,b) a##b -#define __PASTE(a,b) ___PASTE(a,b) +#ifndef __ASSEMBLY__ #ifdef __KERNEL__ -#ifdef __GNUC__ -#include -#endif - -#if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) -#define notrace __attribute__((hotpatch(0,0))) -#else -#define notrace __attribute__((no_instrument_function)) -#endif - -/* Intel compiler defines __GNUC__. So we will overwrite implementations - * coming from above header files here - */ -#ifdef __INTEL_COMPILER -# include -#endif - -/* Clang compiler defines __GNUC__. So we will overwrite implementations - * coming from above header files here - */ -#ifdef __clang__ -#include -#endif - -/* - * Generic compiler-dependent macros required for kernel - * build go below this comment. Actual compiler/compiler version - * specific implementations come from the above header files - */ - -struct ftrace_branch_data { - const char *func; - const char *file; - unsigned line; - union { - struct { - unsigned long correct; - unsigned long incorrect; - }; - struct { - unsigned long miss; - unsigned long hit; - }; - unsigned long miss_hit[2]; - }; -}; - -struct ftrace_likely_data { - struct ftrace_branch_data data; - unsigned long constant; -}; - /* * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code * to disable branch tracing on a per file basis. @@ -332,6 +233,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s * with an explicit memory barrier or atomic instruction that provides the * required ordering. */ +#include #define __READ_ONCE(x, check) \ ({ \ @@ -363,167 +265,6 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s #endif /* __ASSEMBLY__ */ -#ifdef __KERNEL__ -/* - * Allow us to mark functions as 'deprecated' and have gcc emit a nice - * warning for each use, in hopes of speeding the functions removal. - * Usage is: - * int __deprecated foo(void) - */ -#ifndef __deprecated -# define __deprecated /* unimplemented */ -#endif - -#ifdef MODULE -#define __deprecated_for_modules __deprecated -#else -#define __deprecated_for_modules -#endif - -#ifndef __must_check -#define __must_check -#endif - -#ifndef CONFIG_ENABLE_MUST_CHECK -#undef __must_check -#define __must_check -#endif -#ifndef CONFIG_ENABLE_WARN_DEPRECATED -#undef __deprecated -#undef __deprecated_for_modules -#define __deprecated -#define __deprecated_for_modules -#endif - -#ifndef __malloc -#define __malloc -#endif - -/* - * Allow us to avoid 'defined but not used' warnings on functions and data, - * as well as force them to be emitted to the assembly file. - * - * As of gcc 3.4, static functions that are not marked with attribute((used)) - * may be elided from the assembly file. As of gcc 3.4, static data not so - * marked will not be elided, but this may change in a future gcc version. - * - * NOTE: Because distributions shipped with a backported unit-at-a-time - * compiler in gcc 3.3, we must define __used to be __attribute__((used)) - * for gcc >=3.3 instead of 3.4. - * - * In prior versions of gcc, such functions and data would be emitted, but - * would be warned about except with attribute((unused)). - * - * Mark functions that are referenced only in inline assembly as __used so - * the code is emitted even though it appears to be unreferenced. - */ -#ifndef __used -# define __used /* unimplemented */ -#endif - -#ifndef __maybe_unused -# define __maybe_unused /* unimplemented */ -#endif - -#ifndef __always_unused -# define __always_unused /* unimplemented */ -#endif - -#ifndef noinline -#define noinline -#endif - -/* - * Rather then using noinline to prevent stack consumption, use - * noinline_for_stack instead. For documentation reasons. - */ -#define noinline_for_stack noinline - -#ifndef __always_inline -#define __always_inline inline -#endif - -#endif /* __KERNEL__ */ - -/* - * From the GCC manual: - * - * Many functions do not examine any values except their arguments, - * and have no effects except the return value. Basically this is - * just slightly more strict class than the `pure' attribute above, - * since function is not allowed to read global memory. - * - * Note that a function that has pointer arguments and examines the - * data pointed to must _not_ be declared `const'. Likewise, a - * function that calls a non-`const' function usually must not be - * `const'. It does not make sense for a `const' function to return - * `void'. - */ -#ifndef __attribute_const__ -# define __attribute_const__ /* unimplemented */ -#endif - -#ifndef __designated_init -# define __designated_init -#endif - -#ifndef __latent_entropy -# define __latent_entropy -#endif - -#ifndef __randomize_layout -# define __randomize_layout __designated_init -#endif - -#ifndef __no_randomize_layout -# define __no_randomize_layout -#endif - -#ifndef randomized_struct_fields_start -# define randomized_struct_fields_start -# define randomized_struct_fields_end -#endif - -/* - * Tell gcc if a function is cold. The compiler will assume any path - * directly leading to the call is unlikely. - */ - -#ifndef __cold -#define __cold -#endif - -/* Simple shorthand for a section definition */ -#ifndef __section -# define __section(S) __attribute__ ((__section__(#S))) -#endif - -#ifndef __visible -#define __visible -#endif - -#ifndef __nostackprotector -# define __nostackprotector -#endif - -/* - * Assume alignment of return value. - */ -#ifndef __assume_aligned -#define __assume_aligned(a, ...) -#endif - - -/* Are two types/vars the same type (ignoring qualifiers)? */ -#ifndef __same_type -# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) -#endif - -/* Is this type a native word size -- useful for atomic operations */ -#ifndef __native_word -# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) -#endif - /* Compile time object size, -1 for unknown */ #ifndef __compiletime_object_size # define __compiletime_object_size(obj) -1 diff --git a/include/uapi/linux/stddef.h b/include/uapi/linux/stddef.h index 621fa8ac4425..1ec6a7867c46 100644 --- a/include/uapi/linux/stddef.h +++ b/include/uapi/linux/stddef.h @@ -1,4 +1,4 @@ -#include +#include #ifndef __always_inline #define __always_inline inline diff --git a/scripts/headers_install.sh b/scripts/headers_install.sh index fdebd66f8fc1..bbb7f3d35289 100755 --- a/scripts/headers_install.sh +++ b/scripts/headers_install.sh @@ -33,7 +33,7 @@ do sed -r \ -e 's/([ \t(])(__user|__force|__iomem)[ \t]/\1/g' \ -e 's/__attribute_const__([ \t]|$)/\1/g' \ - -e 's@^#include @@' \ + -e 's@^#include @@' \ -e 's/(^|[^a-zA-Z0-9])__packed([^a-zA-Z0-9_]|$)/\1__attribute__((packed))\2/g' \ -e 's/(^|[ \t(])(inline|asm|volatile)([ \t(]|$)/\1__\2__\3/g' \ -e 's@#(ifndef|define|endif[ \t]*/[*])[ \t]*_UAPI@#\1 @' \ -- 2.1.4