[PATCH v5] Makefile: Add build time and compiler info string

[PATCH v5] Makefile: Add build time and compiler info string

[Anup Patel]

From: Wei Fu <wefu@redhat.com>

When we are doing opensbi development, we want to know the build time and
compiler info for debug purpose.
To enable this message, please add "BUILD_INFO=y", like:

```
make BUILD_INFO=y
```

NOTE: `BUILD_INFO=y` will violate "reproducible builds".
So it's ONLY for development and debug purpose, and should NOT be used
in a product which follows "reproducible builds".

Signed-off-by: Wei Fu <wefu@redhat.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
---
Changes since v4:
 - Updated build date format to +%Y-%m-%d %H:%M:%S %z
 - Rename SOURCE_DATE_EPOCH to BUILD_DATE_EPOCH
---
 Makefile           | 31 +++++++++++++++++++++++++++++++
 README.md          | 23 +++++++++++++++++++++++
 lib/sbi/sbi_init.c |  8 ++++++++
 3 files changed, 62 insertions(+)

diff --git a/Makefile b/Makefile
index 16d9dca..9548afd 100644
--- a/Makefile
+++ b/Makefile
@@ -150,6 +150,25 @@ endif
 # Check whether the linker supports creating PIEs
 OPENSBI_LD_PIE := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) $(USE_LD_FLAG) -fPIE -nostdlib -Wl,-pie -x c /dev/null -o /dev/null >/dev/null 2>&1 && echo y || echo n)
 
+# Build Info:
+# OPENSBI_BUILD_TIME_STAMP -- the compilation time stamp
+# OPENSBI_BUILD_COMPILER_VERSION -- the compiler version info
+BUILD_INFO ?= n
+ifeq ($(BUILD_INFO),y)
+OPENSBI_BUILD_DATE_FMT = +%Y-%m-%d %H:%M:%S %z
+ifdef BUILD_DATE_EPOCH
+	OPENSBI_BUILD_TIME_STAMP ?= $(shell date -u -d "@$(BUILD_DATE_EPOCH)" \
+		"$(OPENSBI_BUILD_DATE_FMT)" 2>/dev/null || \
+		date -u -r "$(BUILD_DATE_EPOCH)" \
+		"$(OPENSBI_BUILD_DATE_FMT)" 2>/dev/null || \
+		date -u "$(OPENSBI_BUILD_DATE_FMT)")
+else
+	OPENSBI_BUILD_TIME_STAMP ?= $(shell date "$(OPENSBI_BUILD_DATE_FMT)")
+endif
+OPENSBI_BUILD_COMPILER_VERSION=$(shell $(CC) -v 2>&1 | grep ' version ' | \
+	sed 's/[[:space:]]*$$//')
+endif
+
 # Setup list of objects.mk files
 ifdef PLATFORM
 platform-object-mks=$(shell if [ -d $(platform_src_dir)/ ]; then find $(platform_src_dir) -iname "objects.mk" | sort -r; fi)
@@ -247,6 +266,10 @@ GENFLAGS	+=	-I$(include_dir)
 ifneq ($(OPENSBI_VERSION_GIT),)
 GENFLAGS	+=	-DOPENSBI_VERSION_GIT="\"$(OPENSBI_VERSION_GIT)\""
 endif
+ifeq ($(BUILD_INFO),y)
+GENFLAGS	+=	-DOPENSBI_BUILD_TIME_STAMP="\"$(OPENSBI_BUILD_TIME_STAMP)\""
+GENFLAGS	+=	-DOPENSBI_BUILD_COMPILER_VERSION="\"$(OPENSBI_BUILD_COMPILER_VERSION)\""
+endif
 GENFLAGS	+=	$(libsbiutils-genflags-y)
 GENFLAGS	+=	$(platform-genflags-y)
 GENFLAGS	+=	$(firmware-genflags-y)
@@ -398,6 +421,11 @@ $(build_dir)/%.dep: $(src_dir)/%.c
 $(build_dir)/%.o: $(src_dir)/%.c
 	$(call compile_cc,$@,$<)
 
+ifeq ($(BUILD_INFO),y)
+$(build_dir)/lib/sbi/sbi_init.o: $(libsbi_dir)/sbi_init.c FORCE
+	$(call compile_cc,$@,$<)
+endif
+
 $(build_dir)/%.dep: $(src_dir)/%.S
 	$(call compile_as_dep,$@,$<)
 
@@ -551,3 +579,6 @@ ifeq ($(install_root_dir),$(install_root_dir_default)/usr)
 	$(if $(V), @echo " RM        $(install_root_dir_default)")
 	$(CMD_PREFIX)rm -rf $(install_root_dir_default)
 endif
+
+.PHONY: FORCE
+FORCE:
diff --git a/README.md b/README.md
index 9fdf097..c498af0 100644
--- a/README.md
+++ b/README.md
@@ -254,6 +254,28 @@ to produce broken binaries with missing relocations; it is therefore currently
 recommended that this combination be avoided or *FW_PIC=n* be used to disable
 building OpenSBI as a position-independent binary.
 
+Building with timestamp and compiler info
+-----------------------------------------
+
+When doing development, we may want to know the build time and compiler info
+for debug purpose. OpenSBI can also be built with timestamp and compiler info.
+To build with those info and print it out@boot time, we can just simply add
+`BUILD_INFO=y`, like:
+```
+make BUILD_INFO=y
+```
+
+But if you have used `BUILD_INFO=y`, and want to switch back to `BUILD_INFO=n`,
+you must do
+```
+make clean
+```
+before the next build.
+
+NOTE: Using `BUILD_INFO=y` will violate [reproducible builds]. This definition
+is ONLY for development and debug purpose, and should NOT be used in a product
+which follows "reproducible builds".
+
 Contributing to OpenSBI
 -----------------------
 
@@ -336,3 +358,4 @@ make I=<install_directory> install_docs
 [Doxygen manual]: http://www.doxygen.nl/manual/index.html
 [Kendryte standalone SDK]: https://github.com/kendryte/kendryte-standalone-sdk
 [third party notices]: ThirdPartyNotices.md
+[reproducible builds]: https://reproducible-builds.org
diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
index 843659e..b1c7cf0 100644
--- a/lib/sbi/sbi_init.c
+++ b/lib/sbi/sbi_init.c
@@ -48,6 +48,14 @@ static void sbi_boot_print_banner(struct sbi_scratch *scratch)
 		   OPENSBI_VERSION_MINOR);
 #endif
 
+#ifdef OPENSBI_BUILD_TIME_STAMP
+	sbi_printf("Build time: %s\n", OPENSBI_BUILD_TIME_STAMP);
+#endif
+
+#ifdef OPENSBI_BUILD_COMPILER_VERSION
+	sbi_printf("Build compiler: %s\n", OPENSBI_BUILD_COMPILER_VERSION);
+#endif
+
 	sbi_printf(BANNER);
 }
 
-- 
2.25.1

[PATCH v5] Makefile: Add build time and compiler info string

[Alistair Francis]

On Mon, 2021-10-18 at 09:41 +0530, Anup Patel wrote:
> From: Wei Fu <wefu@redhat.com>
> 
> When we are doing opensbi development, we want to know the build time
> and
> compiler info for debug purpose.
> To enable this message, please add "BUILD_INFO=y", like:
> 
> ```
> make BUILD_INFO=y
> ```
> 
> NOTE: `BUILD_INFO=y` will violate "reproducible builds".
> So it's ONLY for development and debug purpose, and should NOT be used
> in a product which follows "reproducible builds".
> 
> Signed-off-by: Wei Fu <wefu@redhat.com>
> Reviewed-by: Anup Patel <anup.patel@wdc.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
> Changes since v4:
> ?- Updated build date format to +%Y-%m-%d %H:%M:%S %z
> ?- Rename SOURCE_DATE_EPOCH to BUILD_DATE_EPOCH
> ---
> ?Makefile?????????? | 31 +++++++++++++++++++++++++++++++
> ?README.md????????? | 23 +++++++++++++++++++++++
> ?lib/sbi/sbi_init.c |? 8 ++++++++
> ?3 files changed, 62 insertions(+)
> 
> diff --git a/Makefile b/Makefile
> index 16d9dca..9548afd 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -150,6 +150,25 @@ endif
> ?# Check whether the linker supports creating PIEs
> ?OPENSBI_LD_PIE := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG)
> $(USE_LD_FLAG) -fPIE -nostdlib -Wl,-pie -x c /dev/null -o /dev/null
> >/dev/null 2>&1 && echo y || echo n)
> ?
> +# Build Info:
> +# OPENSBI_BUILD_TIME_STAMP -- the compilation time stamp
> +# OPENSBI_BUILD_COMPILER_VERSION -- the compiler version info
> +BUILD_INFO ?= n
> +ifeq ($(BUILD_INFO),y)
> +OPENSBI_BUILD_DATE_FMT = +%Y-%m-%d %H:%M:%S %z
> +ifdef BUILD_DATE_EPOCH
> +???????OPENSBI_BUILD_TIME_STAMP ?= $(shell date -u -d
> "@$(BUILD_DATE_EPOCH)" \
> +???????????????"$(OPENSBI_BUILD_DATE_FMT)" 2>/dev/null || \
> +???????????????date -u -r "$(BUILD_DATE_EPOCH)" \
> +???????????????"$(OPENSBI_BUILD_DATE_FMT)" 2>/dev/null || \
> +???????????????date -u "$(OPENSBI_BUILD_DATE_FMT)")
> +else
> +???????OPENSBI_BUILD_TIME_STAMP ?= $(shell date
> "$(OPENSBI_BUILD_DATE_FMT)")
> +endif
> +OPENSBI_BUILD_COMPILER_VERSION=$(shell $(CC) -v 2>&1 | grep ' version
> ' | \
> +???????sed 's/[[:space:]]*$$//')
> +endif
> +
> ?# Setup list of objects.mk files
> ?ifdef PLATFORM
> ?platform-object-mks=$(shell if [ -d $(platform_src_dir)/ ]; then find
> $(platform_src_dir) -iname "objects.mk" | sort -r; fi)
> @@ -247,6 +266,10 @@ GENFLAGS???+=??????-I$(include_dir)
> ?ifneq ($(OPENSBI_VERSION_GIT),)
> ?GENFLAGS???????+=??????-
> DOPENSBI_VERSION_GIT="\"$(OPENSBI_VERSION_GIT)\""
> ?endif
> +ifeq ($(BUILD_INFO),y)
> +GENFLAGS???????+=??????-
> DOPENSBI_BUILD_TIME_STAMP="\"$(OPENSBI_BUILD_TIME_STAMP)\""
> +GENFLAGS???????+=??????-
> DOPENSBI_BUILD_COMPILER_VERSION="\"$(OPENSBI_BUILD_COMPILER_VERSION)\""
> +endif
> ?GENFLAGS???????+=??????$(libsbiutils-genflags-y)
> ?GENFLAGS???????+=??????$(platform-genflags-y)
> ?GENFLAGS???????+=??????$(firmware-genflags-y)
> @@ -398,6 +421,11 @@ $(build_dir)/%.dep: $(src_dir)/%.c
> ?$(build_dir)/%.o: $(src_dir)/%.c
> ????????$(call compile_cc,$@,$<)
> ?
> +ifeq ($(BUILD_INFO),y)
> +$(build_dir)/lib/sbi/sbi_init.o: $(libsbi_dir)/sbi_init.c FORCE
> +???????$(call compile_cc,$@,$<)
> +endif
> +
> ?$(build_dir)/%.dep: $(src_dir)/%.S
> ????????$(call compile_as_dep,$@,$<)
> ?
> @@ -551,3 +579,6 @@ ifeq
> ($(install_root_dir),$(install_root_dir_default)/usr)
> ????????$(if $(V), @echo " RM??????? $(install_root_dir_default)")
> ????????$(CMD_PREFIX)rm -rf $(install_root_dir_default)
> ?endif
> +
> +.PHONY: FORCE
> +FORCE:
> diff --git a/README.md b/README.md
> index 9fdf097..c498af0 100644
> --- a/README.md
> +++ b/README.md
> @@ -254,6 +254,28 @@ to produce broken binaries with missing
> relocations; it is therefore currently
> ?recommended that this combination be avoided or *FW_PIC=n* be used to
> disable
> ?building OpenSBI as a position-independent binary.
> ?
> +Building with timestamp and compiler info
> +-----------------------------------------
> +
> +When doing development, we may want to know the build time and
> compiler info
> +for debug purpose. OpenSBI can also be built with timestamp and
> compiler info.
> +To build with those info and print it out at boot time, we can just
> simply add
> +`BUILD_INFO=y`, like:
> +```
> +make BUILD_INFO=y
> +```
> +
> +But if you have used `BUILD_INFO=y`, and want to switch back to
> `BUILD_INFO=n`,
> +you must do
> +```
> +make clean
> +```
> +before the next build.
> +
> +NOTE: Using `BUILD_INFO=y` will violate [reproducible builds]. This
> definition
> +is ONLY for development and debug purpose, and should NOT be used in a
> product
> +which follows "reproducible builds".
> +
> ?Contributing to OpenSBI
> ?-----------------------
> ?
> @@ -336,3 +358,4 @@ make I=<install_directory> install_docs
> ?[Doxygen manual]: http://www.doxygen.nl/manual/index.html
> ?[Kendryte standalone SDK]:
> https://github.com/kendryte/kendryte-standalone-sdk
> ?[third party notices]: ThirdPartyNotices.md
> +[reproducible builds]: https://reproducible-builds.org
> diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
> index 843659e..b1c7cf0 100644
> --- a/lib/sbi/sbi_init.c
> +++ b/lib/sbi/sbi_init.c
> @@ -48,6 +48,14 @@ static void sbi_boot_print_banner(struct sbi_scratch
> *scratch)
> ?????????????????? OPENSBI_VERSION_MINOR);
> ?#endif
> ?
> +#ifdef OPENSBI_BUILD_TIME_STAMP
> +???????sbi_printf("Build time: %s\n", OPENSBI_BUILD_TIME_STAMP);
> +#endif
> +
> +#ifdef OPENSBI_BUILD_COMPILER_VERSION
> +???????sbi_printf("Build compiler: %s\n",
> OPENSBI_BUILD_COMPILER_VERSION);
> +#endif
> +
> ????????sbi_printf(BANNER);
> ?}
> ?

[PATCH v5] Makefile: Add build time and compiler info string

[Bin Meng]

Hi Anup,

On Mon, Oct 18, 2021 at 12:13 PM Anup Patel <anup.patel@wdc.com> wrote:
>
> From: Wei Fu <wefu@redhat.com>
>
> When we are doing opensbi development, we want to know the build time and
> compiler info for debug purpose.
> To enable this message, please add "BUILD_INFO=y", like:
>
> ```
> make BUILD_INFO=y
> ```
>
> NOTE: `BUILD_INFO=y` will violate "reproducible builds".
> So it's ONLY for development and debug purpose, and should NOT be used
> in a product which follows "reproducible builds".

As I pointed out in v4, with BUILD_INFO=y we can still achieve
reproducible builds with BUILD_DATE_EPOCH, so this statement is not
entirely true.

The question is whether we should just drop introducing BUILD_INFO and
turn this on for all builds. If reproducible builds is required,
define BUILD_DATE_EPOCH.

>
> Signed-off-by: Wei Fu <wefu@redhat.com>
> Reviewed-by: Anup Patel <anup.patel@wdc.com>
> ---
> Changes since v4:
>  - Updated build date format to +%Y-%m-%d %H:%M:%S %z
>  - Rename SOURCE_DATE_EPOCH to BUILD_DATE_EPOCH
> ---
>  Makefile           | 31 +++++++++++++++++++++++++++++++
>  README.md          | 23 +++++++++++++++++++++++
>  lib/sbi/sbi_init.c |  8 ++++++++
>  3 files changed, 62 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index 16d9dca..9548afd 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -150,6 +150,25 @@ endif
>  # Check whether the linker supports creating PIEs
>  OPENSBI_LD_PIE := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) $(USE_LD_FLAG) -fPIE -nostdlib -Wl,-pie -x c /dev/null -o /dev/null >/dev/null 2>&1 && echo y || echo n)
>
> +# Build Info:
> +# OPENSBI_BUILD_TIME_STAMP -- the compilation time stamp
> +# OPENSBI_BUILD_COMPILER_VERSION -- the compiler version info
> +BUILD_INFO ?= n
> +ifeq ($(BUILD_INFO),y)
> +OPENSBI_BUILD_DATE_FMT = +%Y-%m-%d %H:%M:%S %z
> +ifdef BUILD_DATE_EPOCH
> +       OPENSBI_BUILD_TIME_STAMP ?= $(shell date -u -d "@$(BUILD_DATE_EPOCH)" \
> +               "$(OPENSBI_BUILD_DATE_FMT)" 2>/dev/null || \
> +               date -u -r "$(BUILD_DATE_EPOCH)" \
> +               "$(OPENSBI_BUILD_DATE_FMT)" 2>/dev/null || \
> +               date -u "$(OPENSBI_BUILD_DATE_FMT)")
> +else
> +       OPENSBI_BUILD_TIME_STAMP ?= $(shell date "$(OPENSBI_BUILD_DATE_FMT)")
> +endif
> +OPENSBI_BUILD_COMPILER_VERSION=$(shell $(CC) -v 2>&1 | grep ' version ' | \
> +       sed 's/[[:space:]]*$$//')
> +endif
> +
>  # Setup list of objects.mk files
>  ifdef PLATFORM
>  platform-object-mks=$(shell if [ -d $(platform_src_dir)/ ]; then find $(platform_src_dir) -iname "objects.mk" | sort -r; fi)
> @@ -247,6 +266,10 @@ GENFLAGS   +=      -I$(include_dir)
>  ifneq ($(OPENSBI_VERSION_GIT),)
>  GENFLAGS       +=      -DOPENSBI_VERSION_GIT="\"$(OPENSBI_VERSION_GIT)\""
>  endif
> +ifeq ($(BUILD_INFO),y)
> +GENFLAGS       +=      -DOPENSBI_BUILD_TIME_STAMP="\"$(OPENSBI_BUILD_TIME_STAMP)\""
> +GENFLAGS       +=      -DOPENSBI_BUILD_COMPILER_VERSION="\"$(OPENSBI_BUILD_COMPILER_VERSION)\""
> +endif
>  GENFLAGS       +=      $(libsbiutils-genflags-y)
>  GENFLAGS       +=      $(platform-genflags-y)
>  GENFLAGS       +=      $(firmware-genflags-y)
> @@ -398,6 +421,11 @@ $(build_dir)/%.dep: $(src_dir)/%.c
>  $(build_dir)/%.o: $(src_dir)/%.c
>         $(call compile_cc,$@,$<)
>
> +ifeq ($(BUILD_INFO),y)
> +$(build_dir)/lib/sbi/sbi_init.o: $(libsbi_dir)/sbi_init.c FORCE
> +       $(call compile_cc,$@,$<)
> +endif
> +
>  $(build_dir)/%.dep: $(src_dir)/%.S
>         $(call compile_as_dep,$@,$<)
>
> @@ -551,3 +579,6 @@ ifeq ($(install_root_dir),$(install_root_dir_default)/usr)
>         $(if $(V), @echo " RM        $(install_root_dir_default)")
>         $(CMD_PREFIX)rm -rf $(install_root_dir_default)
>  endif
> +
> +.PHONY: FORCE
> +FORCE:
> diff --git a/README.md b/README.md
> index 9fdf097..c498af0 100644
> --- a/README.md
> +++ b/README.md
> @@ -254,6 +254,28 @@ to produce broken binaries with missing relocations; it is therefore currently
>  recommended that this combination be avoided or *FW_PIC=n* be used to disable
>  building OpenSBI as a position-independent binary.
>
> +Building with timestamp and compiler info
> +-----------------------------------------
> +
> +When doing development, we may want to know the build time and compiler info
> +for debug purpose. OpenSBI can also be built with timestamp and compiler info.
> +To build with those info and print it out at boot time, we can just simply add
> +`BUILD_INFO=y`, like:
> +```
> +make BUILD_INFO=y
> +```
> +
> +But if you have used `BUILD_INFO=y`, and want to switch back to `BUILD_INFO=n`,
> +you must do
> +```
> +make clean
> +```
> +before the next build.
> +
> +NOTE: Using `BUILD_INFO=y` will violate [reproducible builds]. This definition
> +is ONLY for development and debug purpose, and should NOT be used in a product
> +which follows "reproducible builds".
> +
>  Contributing to OpenSBI
>  -----------------------
>
> @@ -336,3 +358,4 @@ make I=<install_directory> install_docs
>  [Doxygen manual]: http://www.doxygen.nl/manual/index.html
>  [Kendryte standalone SDK]: https://github.com/kendryte/kendryte-standalone-sdk
>  [third party notices]: ThirdPartyNotices.md
> +[reproducible builds]: https://reproducible-builds.org
> diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
> index 843659e..b1c7cf0 100644
> --- a/lib/sbi/sbi_init.c
> +++ b/lib/sbi/sbi_init.c
> @@ -48,6 +48,14 @@ static void sbi_boot_print_banner(struct sbi_scratch *scratch)
>                    OPENSBI_VERSION_MINOR);
>  #endif
>
> +#ifdef OPENSBI_BUILD_TIME_STAMP
> +       sbi_printf("Build time: %s\n", OPENSBI_BUILD_TIME_STAMP);
> +#endif
> +
> +#ifdef OPENSBI_BUILD_COMPILER_VERSION
> +       sbi_printf("Build compiler: %s\n", OPENSBI_BUILD_COMPILER_VERSION);
> +#endif
> +
>         sbi_printf(BANNER);
>  }
>

Regards,
Bin

[PATCH v5] Makefile: Add build time and compiler info string

[Anup Patel]

On Mon, Oct 18, 2021 at 11:27 AM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> Hi Anup,
>
> On Mon, Oct 18, 2021 at 12:13 PM Anup Patel <anup.patel@wdc.com> wrote:
> >
> > From: Wei Fu <wefu@redhat.com>
> >
> > When we are doing opensbi development, we want to know the build time and
> > compiler info for debug purpose.
> > To enable this message, please add "BUILD_INFO=y", like:
> >
> > ```
> > make BUILD_INFO=y
> > ```
> >
> > NOTE: `BUILD_INFO=y` will violate "reproducible builds".
> > So it's ONLY for development and debug purpose, and should NOT be used
> > in a product which follows "reproducible builds".
>
> As I pointed out in v4, with BUILD_INFO=y we can still achieve
> reproducible builds with BUILD_DATE_EPOCH, so this statement is not
> entirely true.

Yes, but BUILD_DATE_EPOCH is optional and generally people will not
specify BUILD_DATE_EPOCH unless they want a reproducible build.

I will certainly update the "NOTE:" in the commit description to clearly
state when reproducible builds are violated.

>
> The question is whether we should just drop introducing BUILD_INFO and
> turn this on for all builds. If reproducible builds is required,
> define BUILD_DATE_EPOCH.

I think we should keep both BUILD_INFO and BUILD_DATA_EPOCH
because of the reason I mentioned above.

Regards,
Anup

>
> >
> > Signed-off-by: Wei Fu <wefu@redhat.com>
> > Reviewed-by: Anup Patel <anup.patel@wdc.com>
> > ---
> > Changes since v4:
> >  - Updated build date format to +%Y-%m-%d %H:%M:%S %z
> >  - Rename SOURCE_DATE_EPOCH to BUILD_DATE_EPOCH
> > ---
> >  Makefile           | 31 +++++++++++++++++++++++++++++++
> >  README.md          | 23 +++++++++++++++++++++++
> >  lib/sbi/sbi_init.c |  8 ++++++++
> >  3 files changed, 62 insertions(+)
> >
> > diff --git a/Makefile b/Makefile
> > index 16d9dca..9548afd 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -150,6 +150,25 @@ endif
> >  # Check whether the linker supports creating PIEs
> >  OPENSBI_LD_PIE := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) $(USE_LD_FLAG) -fPIE -nostdlib -Wl,-pie -x c /dev/null -o /dev/null >/dev/null 2>&1 && echo y || echo n)
> >
> > +# Build Info:
> > +# OPENSBI_BUILD_TIME_STAMP -- the compilation time stamp
> > +# OPENSBI_BUILD_COMPILER_VERSION -- the compiler version info
> > +BUILD_INFO ?= n
> > +ifeq ($(BUILD_INFO),y)
> > +OPENSBI_BUILD_DATE_FMT = +%Y-%m-%d %H:%M:%S %z
> > +ifdef BUILD_DATE_EPOCH
> > +       OPENSBI_BUILD_TIME_STAMP ?= $(shell date -u -d "@$(BUILD_DATE_EPOCH)" \
> > +               "$(OPENSBI_BUILD_DATE_FMT)" 2>/dev/null || \
> > +               date -u -r "$(BUILD_DATE_EPOCH)" \
> > +               "$(OPENSBI_BUILD_DATE_FMT)" 2>/dev/null || \
> > +               date -u "$(OPENSBI_BUILD_DATE_FMT)")
> > +else
> > +       OPENSBI_BUILD_TIME_STAMP ?= $(shell date "$(OPENSBI_BUILD_DATE_FMT)")
> > +endif
> > +OPENSBI_BUILD_COMPILER_VERSION=$(shell $(CC) -v 2>&1 | grep ' version ' | \
> > +       sed 's/[[:space:]]*$$//')
> > +endif
> > +
> >  # Setup list of objects.mk files
> >  ifdef PLATFORM
> >  platform-object-mks=$(shell if [ -d $(platform_src_dir)/ ]; then find $(platform_src_dir) -iname "objects.mk" | sort -r; fi)
> > @@ -247,6 +266,10 @@ GENFLAGS   +=      -I$(include_dir)
> >  ifneq ($(OPENSBI_VERSION_GIT),)
> >  GENFLAGS       +=      -DOPENSBI_VERSION_GIT="\"$(OPENSBI_VERSION_GIT)\""
> >  endif
> > +ifeq ($(BUILD_INFO),y)
> > +GENFLAGS       +=      -DOPENSBI_BUILD_TIME_STAMP="\"$(OPENSBI_BUILD_TIME_STAMP)\""
> > +GENFLAGS       +=      -DOPENSBI_BUILD_COMPILER_VERSION="\"$(OPENSBI_BUILD_COMPILER_VERSION)\""
> > +endif
> >  GENFLAGS       +=      $(libsbiutils-genflags-y)
> >  GENFLAGS       +=      $(platform-genflags-y)
> >  GENFLAGS       +=      $(firmware-genflags-y)
> > @@ -398,6 +421,11 @@ $(build_dir)/%.dep: $(src_dir)/%.c
> >  $(build_dir)/%.o: $(src_dir)/%.c
> >         $(call compile_cc,$@,$<)
> >
> > +ifeq ($(BUILD_INFO),y)
> > +$(build_dir)/lib/sbi/sbi_init.o: $(libsbi_dir)/sbi_init.c FORCE
> > +       $(call compile_cc,$@,$<)
> > +endif
> > +
> >  $(build_dir)/%.dep: $(src_dir)/%.S
> >         $(call compile_as_dep,$@,$<)
> >
> > @@ -551,3 +579,6 @@ ifeq ($(install_root_dir),$(install_root_dir_default)/usr)
> >         $(if $(V), @echo " RM        $(install_root_dir_default)")
> >         $(CMD_PREFIX)rm -rf $(install_root_dir_default)
> >  endif
> > +
> > +.PHONY: FORCE
> > +FORCE:
> > diff --git a/README.md b/README.md
> > index 9fdf097..c498af0 100644
> > --- a/README.md
> > +++ b/README.md
> > @@ -254,6 +254,28 @@ to produce broken binaries with missing relocations; it is therefore currently
> >  recommended that this combination be avoided or *FW_PIC=n* be used to disable
> >  building OpenSBI as a position-independent binary.
> >
> > +Building with timestamp and compiler info
> > +-----------------------------------------
> > +
> > +When doing development, we may want to know the build time and compiler info
> > +for debug purpose. OpenSBI can also be built with timestamp and compiler info.
> > +To build with those info and print it out at boot time, we can just simply add
> > +`BUILD_INFO=y`, like:
> > +```
> > +make BUILD_INFO=y
> > +```
> > +
> > +But if you have used `BUILD_INFO=y`, and want to switch back to `BUILD_INFO=n`,
> > +you must do
> > +```
> > +make clean
> > +```
> > +before the next build.
> > +
> > +NOTE: Using `BUILD_INFO=y` will violate [reproducible builds]. This definition
> > +is ONLY for development and debug purpose, and should NOT be used in a product
> > +which follows "reproducible builds".
> > +
> >  Contributing to OpenSBI
> >  -----------------------
> >
> > @@ -336,3 +358,4 @@ make I=<install_directory> install_docs
> >  [Doxygen manual]: http://www.doxygen.nl/manual/index.html
> >  [Kendryte standalone SDK]: https://github.com/kendryte/kendryte-standalone-sdk
> >  [third party notices]: ThirdPartyNotices.md
> > +[reproducible builds]: https://reproducible-builds.org
> > diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
> > index 843659e..b1c7cf0 100644
> > --- a/lib/sbi/sbi_init.c
> > +++ b/lib/sbi/sbi_init.c
> > @@ -48,6 +48,14 @@ static void sbi_boot_print_banner(struct sbi_scratch *scratch)
> >                    OPENSBI_VERSION_MINOR);
> >  #endif
> >
> > +#ifdef OPENSBI_BUILD_TIME_STAMP
> > +       sbi_printf("Build time: %s\n", OPENSBI_BUILD_TIME_STAMP);
> > +#endif
> > +
> > +#ifdef OPENSBI_BUILD_COMPILER_VERSION
> > +       sbi_printf("Build compiler: %s\n", OPENSBI_BUILD_COMPILER_VERSION);
> > +#endif
> > +
> >         sbi_printf(BANNER);
> >  }
> >
>
> Regards,
> Bin

[PATCH v5] Makefile: Add build time and compiler info string

[Bin Meng]

On Mon, Oct 18, 2021 at 2:17 PM Anup Patel <anup@brainfault.org> wrote:
>
> On Mon, Oct 18, 2021 at 11:27 AM Bin Meng <bmeng.cn@gmail.com> wrote:
> >
> > Hi Anup,
> >
> > On Mon, Oct 18, 2021 at 12:13 PM Anup Patel <anup.patel@wdc.com> wrote:
> > >
> > > From: Wei Fu <wefu@redhat.com>
> > >
> > > When we are doing opensbi development, we want to know the build time and
> > > compiler info for debug purpose.
> > > To enable this message, please add "BUILD_INFO=y", like:
> > >
> > > ```
> > > make BUILD_INFO=y
> > > ```
> > >
> > > NOTE: `BUILD_INFO=y` will violate "reproducible builds".
> > > So it's ONLY for development and debug purpose, and should NOT be used
> > > in a product which follows "reproducible builds".
> >
> > As I pointed out in v4, with BUILD_INFO=y we can still achieve
> > reproducible builds with BUILD_DATE_EPOCH, so this statement is not
> > entirely true.
>
> Yes, but BUILD_DATE_EPOCH is optional and generally people will not
> specify BUILD_DATE_EPOCH unless they want a reproducible build.
>

If this BUILD_DATE_EPOCH is not needed at all, I am not sure why do we
still keep

ifdef BUILD_DATE_EPOCH
       OPENSBI_BUILD_TIME_STAMP ?= $(shell date -u -d "@$(BUILD_DATE_EPOCH)" \
               "$(OPENSBI_BUILD_DATE_FMT)" 2>/dev/null || \
               date -u -r "$(BUILD_DATE_EPOCH)" \
               "$(OPENSBI_BUILD_DATE_FMT)" 2>/dev/null || \
               date -u "$(OPENSBI_BUILD_DATE_FMT)")
else

> I will certainly update the "NOTE:" in the commit description to clearly
> state when reproducible builds are violated.
>
> >
> > The question is whether we should just drop introducing BUILD_INFO and
> > turn this on for all builds. If reproducible builds is required,
> > define BUILD_DATE_EPOCH.
>
> I think we should keep both BUILD_INFO and BUILD_DATA_EPOCH
> because of the reason I mentioned above.
>

Regards,
Bin

[PATCH v5] Makefile: Add build time and compiler info string

[Andreas Schwab]

On Okt 18 2021, Bin Meng wrote:

> If this BUILD_DATE_EPOCH is not needed at all, I am not sure why do we
> still keep

BUILD_DATE_EPOCH is also non-standard.  The standard variable is
SOURCE_DATE_EPOCH.

Andreas.

-- 
Andreas Schwab, schwab at linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

[PATCH v5] Makefile: Add build time and compiler info string

[Bin Meng]

On Mon, Oct 18, 2021 at 3:44 PM Andreas Schwab <schwab@linux-m68k.org> wrote:
>
> On Okt 18 2021, Bin Meng wrote:
>
> > If this BUILD_DATE_EPOCH is not needed at all, I am not sure why do we
> > still keep
>
> BUILD_DATE_EPOCH is also non-standard.  The standard variable is
> SOURCE_DATE_EPOCH.
>

Yep, it's SOURCE_DATE_EPOCH in v4, not sure why Anup changed the name in v5.

SOURCE_DATE_EPOCH is well documented and is the way for distros to
generate "reproducible builds".

I would vote to completely drop the "BUILD_INFO=y" as it is not necessary.

Regards,
Bin

[PATCH v5] Makefile: Add build time and compiler info string

[Anup Patel]

On Mon, Oct 18, 2021 at 1:42 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> On Mon, Oct 18, 2021 at 3:44 PM Andreas Schwab <schwab@linux-m68k.org> wrote:
> >
> > On Okt 18 2021, Bin Meng wrote:
> >
> > > If this BUILD_DATE_EPOCH is not needed at all, I am not sure why do we
> > > still keep
> >
> > BUILD_DATE_EPOCH is also non-standard.  The standard variable is
> > SOURCE_DATE_EPOCH.
> >
>
> Yep, it's SOURCE_DATE_EPOCH in v4, not sure why Anup changed the name in v5.

Yes, I changed it to BUILD_DATE_EPOCH to imply that it is related to
BUILD_INFO. I was not aware that SOURCE_DATE_EPOCH is a
standard name. I will rename it to SOURCE_DATE_EPOCH in v6.

>
> SOURCE_DATE_EPOCH is well documented and is the way for distros to
> generate "reproducible builds".
>
> I would vote to completely drop the "BUILD_INFO=y" as it is not necessary.

I don't agree with this. The BUILD_INFO helps us totally disable build
information whereas SOURCE_DATE_EPOCH helps us override the
build date/time when BUILD_INFO=y.

Regards,
Anup

[PATCH v5] Makefile: Add build time and compiler info string

[Bin Meng]

On Mon, Oct 18, 2021 at 6:08 PM Anup Patel <anup@brainfault.org> wrote:
>
> On Mon, Oct 18, 2021 at 1:42 PM Bin Meng <bmeng.cn@gmail.com> wrote:
> >
> > On Mon, Oct 18, 2021 at 3:44 PM Andreas Schwab <schwab@linux-m68k.org> wrote:
> > >
> > > On Okt 18 2021, Bin Meng wrote:
> > >
> > > > If this BUILD_DATE_EPOCH is not needed at all, I am not sure why do we
> > > > still keep
> > >
> > > BUILD_DATE_EPOCH is also non-standard.  The standard variable is
> > > SOURCE_DATE_EPOCH.
> > >
> >
> > Yep, it's SOURCE_DATE_EPOCH in v4, not sure why Anup changed the name in v5.
>
> Yes, I changed it to BUILD_DATE_EPOCH to imply that it is related to
> BUILD_INFO. I was not aware that SOURCE_DATE_EPOCH is a
> standard name. I will rename it to SOURCE_DATE_EPOCH in v6.
>
> >
> > SOURCE_DATE_EPOCH is well documented and is the way for distros to
> > generate "reproducible builds".
> >
> > I would vote to completely drop the "BUILD_INFO=y" as it is not necessary.
>
> I don't agree with this. The BUILD_INFO helps us totally disable build
> information whereas SOURCE_DATE_EPOCH helps us override the
> build date/time when BUILD_INFO=y.

But what benefits us to provide the capability to conditionally
disable the build information? I think that is useful and can be
turned on unconditionally, and we can still generate reproducible
builds with SOURCE_DATE_EPOCH.

Regards,
Bin

[PATCH v5] Makefile: Add build time and compiler info string

[Anup Patel]

On Mon, Oct 18, 2021 at 3:41 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> On Mon, Oct 18, 2021 at 6:08 PM Anup Patel <anup@brainfault.org> wrote:
> >
> > On Mon, Oct 18, 2021 at 1:42 PM Bin Meng <bmeng.cn@gmail.com> wrote:
> > >
> > > On Mon, Oct 18, 2021 at 3:44 PM Andreas Schwab <schwab@linux-m68k.org> wrote:
> > > >
> > > > On Okt 18 2021, Bin Meng wrote:
> > > >
> > > > > If this BUILD_DATE_EPOCH is not needed at all, I am not sure why do we
> > > > > still keep
> > > >
> > > > BUILD_DATE_EPOCH is also non-standard.  The standard variable is
> > > > SOURCE_DATE_EPOCH.
> > > >
> > >
> > > Yep, it's SOURCE_DATE_EPOCH in v4, not sure why Anup changed the name in v5.
> >
> > Yes, I changed it to BUILD_DATE_EPOCH to imply that it is related to
> > BUILD_INFO. I was not aware that SOURCE_DATE_EPOCH is a
> > standard name. I will rename it to SOURCE_DATE_EPOCH in v6.
> >
> > >
> > > SOURCE_DATE_EPOCH is well documented and is the way for distros to
> > > generate "reproducible builds".
> > >
> > > I would vote to completely drop the "BUILD_INFO=y" as it is not necessary.
> >
> > I don't agree with this. The BUILD_INFO helps us totally disable build
> > information whereas SOURCE_DATE_EPOCH helps us override the
> > build date/time when BUILD_INFO=y.
>
> But what benefits us to provide the capability to conditionally
> disable the build information? I think that is useful and can be
> turned on unconditionally, and we can still generate reproducible
> builds with SOURCE_DATE_EPOCH.

Users will have to figure-out/remember a fixed build date when
using SOURCE_DATA_EPOCH for reproducible builds whereas
users don't need to do anything when BUILD_INFO is not defined.

BUILD_INFO being not defined is easy/convenient for users
creating reproducible builds by default. This is also reflected by
the "BUILD_INFO ?= n" line.

Regards,
Anup

[PATCH v5] Makefile: Add build time and compiler info string

[Andreas Schwab]

On Okt 18 2021, Anup Patel wrote:

> Users will have to figure-out/remember a fixed build date when
> using SOURCE_DATA_EPOCH for reproducible builds whereas
> users don't need to do anything when BUILD_INFO is not defined.

Users who care about reproducible builds already know how to set
SOURCE_DATA_EPOCH.

Andreas.

-- 
Andreas Schwab, schwab at linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

[PATCH v5] Makefile: Add build time and compiler info string

[Anup Patel]

On Mon, Oct 18, 2021 at 3:58 PM Andreas Schwab <schwab@linux-m68k.org> wrote:
>
> On Okt 18 2021, Anup Patel wrote:
>
> > Users will have to figure-out/remember a fixed build date when
> > using SOURCE_DATA_EPOCH for reproducible builds whereas
> > users don't need to do anything when BUILD_INFO is not defined.
>
> Users who care about reproducible builds already know how to set
> SOURCE_DATA_EPOCH.
>

@Alistair Francis Are you okay removing BUILD_INFO and having it
always enabled ?

Regards,
Anup

[PATCH v5] Makefile: Add build time and compiler info string

[Alistair Francis]

On Mon, 2021-10-18 at 16:06 +0530, Anup Patel wrote:
> On Mon, Oct 18, 2021 at 3:58 PM Andreas Schwab <schwab@linux-m68k.org>
> wrote:
> > 
> > On Okt 18 2021, Anup Patel wrote:
> > 
> > > Users will have to figure-out/remember a fixed build date when
> > > using SOURCE_DATA_EPOCH for reproducible builds whereas
> > > users don't need to do anything when BUILD_INFO is not defined.
> > 
> > Users who care about reproducible builds already know how to set
> > SOURCE_DATA_EPOCH.
> > 
> 
> @Alistair Francis Are you okay removing BUILD_INFO and having it
> always enabled ?

I think it should be disabled by default.

We have not had a timestamp for awhile and it hasn't impacted people
too much.

The reproducible build documentation specifically says that timestamps
are best avoided (https://reproducible-builds.org/docs/timestamps/). I
think they sum it up well that it doesn't add much value, except for a
few specific circumstances.

So I don't see a good justification for enabling it by default, even
with SOURCE_DATE_EPOCH (good catch on the name chage, I missed that).

Alistair

> 
> Regards,
> Anup

[PATCH v5] Makefile: Add build time and compiler info string

[Bin Meng]

On Tue, Oct 19, 2021 at 8:23 AM Alistair Francis
<Alistair.Francis@wdc.com> wrote:
>
> On Mon, 2021-10-18 at 16:06 +0530, Anup Patel wrote:
> > On Mon, Oct 18, 2021 at 3:58 PM Andreas Schwab <schwab@linux-m68k.org>
> > wrote:
> > >
> > > On Okt 18 2021, Anup Patel wrote:
> > >
> > > > Users will have to figure-out/remember a fixed build date when
> > > > using SOURCE_DATA_EPOCH for reproducible builds whereas
> > > > users don't need to do anything when BUILD_INFO is not defined.
> > >
> > > Users who care about reproducible builds already know how to set
> > > SOURCE_DATA_EPOCH.
> > >
> >
> > @Alistair Francis Are you okay removing BUILD_INFO and having it
> > always enabled ?
>
> I think it should be disabled by default.
>
> We have not had a timestamp for awhile and it hasn't impacted people
> too much.
>
> The reproducible build documentation specifically says that timestamps
> are best avoided (https://reproducible-builds.org/docs/timestamps/). I
> think they sum it up well that it doesn't add much value, except for a
> few specific circumstances.
>
> So I don't see a good justification for enabling it by default, even
> with SOURCE_DATE_EPOCH (good catch on the name chage, I missed that).
>

If that, please reword the following part of the commit message as
well as updating the docs regarding "reproducible builds". Having
BUILD_INFO=n does not mean we are reproducible builds by default.

NOTE: `BUILD_INFO=y` will violate "reproducible builds".
So it's ONLY for development and debug purpose, and should NOT be used
in a product which follows "reproducible builds".

Regards,
Bin

[PATCH v5] Makefile: Add build time and compiler info string

[Bin Meng]

On Mon, Oct 18, 2021 at 6:19 PM Anup Patel <anup@brainfault.org> wrote:
>
> On Mon, Oct 18, 2021 at 3:41 PM Bin Meng <bmeng.cn@gmail.com> wrote:
> >
> > On Mon, Oct 18, 2021 at 6:08 PM Anup Patel <anup@brainfault.org> wrote:
> > >
> > > On Mon, Oct 18, 2021 at 1:42 PM Bin Meng <bmeng.cn@gmail.com> wrote:
> > > >
> > > > On Mon, Oct 18, 2021 at 3:44 PM Andreas Schwab <schwab@linux-m68k.org> wrote:
> > > > >
> > > > > On Okt 18 2021, Bin Meng wrote:
> > > > >
> > > > > > If this BUILD_DATE_EPOCH is not needed at all, I am not sure why do we
> > > > > > still keep
> > > > >
> > > > > BUILD_DATE_EPOCH is also non-standard.  The standard variable is
> > > > > SOURCE_DATE_EPOCH.
> > > > >
> > > >
> > > > Yep, it's SOURCE_DATE_EPOCH in v4, not sure why Anup changed the name in v5.
> > >
> > > Yes, I changed it to BUILD_DATE_EPOCH to imply that it is related to
> > > BUILD_INFO. I was not aware that SOURCE_DATE_EPOCH is a
> > > standard name. I will rename it to SOURCE_DATE_EPOCH in v6.
> > >
> > > >
> > > > SOURCE_DATE_EPOCH is well documented and is the way for distros to
> > > > generate "reproducible builds".
> > > >
> > > > I would vote to completely drop the "BUILD_INFO=y" as it is not necessary.
> > >
> > > I don't agree with this. The BUILD_INFO helps us totally disable build
> > > information whereas SOURCE_DATE_EPOCH helps us override the
> > > build date/time when BUILD_INFO=y.
> >
> > But what benefits us to provide the capability to conditionally
> > disable the build information? I think that is useful and can be
> > turned on unconditionally, and we can still generate reproducible
> > builds with SOURCE_DATE_EPOCH.
>
> Users will have to figure-out/remember a fixed build date when
> using SOURCE_DATA_EPOCH for reproducible builds whereas
> users don't need to do anything when BUILD_INFO is not defined.
>

This is not 100% true as with current OpenSBI we never claim its build
is fully reproducible. For example, one can easily add __DATE__ to the
source codes which will alter unless we provide SOURCE_DATA_EPOCH.

> BUILD_INFO being not defined is easy/convenient for users
> creating reproducible builds by default. This is also reflected by
> the "BUILD_INFO ?= n" line.

Regards,
Bin

[PATCH v5] Makefile: Add build time and compiler info string

[Peter Korsgaard]

>>>>> "Bin" == Bin Meng <bmeng.cn@gmail.com> writes:

Hi,

 >> Users will have to figure-out/remember a fixed build date when
 >> using SOURCE_DATA_EPOCH for reproducible builds whereas
 >> users don't need to do anything when BUILD_INFO is not defined.

 > This is not 100% true as with current OpenSBI we never claim its build
 > is fully reproducible. For example, one can easily add __DATE__ to the
 > source codes which will alter unless we provide SOURCE_DATA_EPOCH.

Notice that GCC >= 7 does in fact look for SOURCE_DATE_EPOCH in the
environment and change the behaviour of the __DATE__ / __TIME__ macros:

https://gcc.gnu.org/onlinedocs/cpp/Environment-Variables.html

-- 
Bye, Peter Korsgaard

[PATCH v5] Makefile: Add build time and compiler info string

[Peter Korsgaard]

>>>>> "Bin" == Bin Meng <bmeng.cn@gmail.com> writes:

 > Hi Anup,
 > On Mon, Oct 18, 2021 at 12:13 PM Anup Patel <anup.patel@wdc.com> wrote:
 >> 
 >> From: Wei Fu <wefu@redhat.com>
 >> 
 >> When we are doing opensbi development, we want to know the build time and
 >> compiler info for debug purpose.
 >> To enable this message, please add "BUILD_INFO=y", like:
 >> 
 >> ```
 >> make BUILD_INFO=y
 >> ```
 >> 
 >> NOTE: `BUILD_INFO=y` will violate "reproducible builds".
 >> So it's ONLY for development and debug purpose, and should NOT be used
 >> in a product which follows "reproducible builds".

 > As I pointed out in v4, with BUILD_INFO=y we can still achieve
 > reproducible builds with BUILD_DATE_EPOCH, so this statement is not
 > entirely true.

 > The question is whether we should just drop introducing BUILD_INFO and
 > turn this on for all builds. If reproducible builds is required,
 > define BUILD_DATE_EPOCH.

Agreed, though BUILD_DATE_EPOCH seems to be specific to opensbi. Why was
this changed from SOURCE_DATE_EPOCH? In Buildroot at least, we only set
SOURCE_DATE_EPOCH when we want reproducible builds and the spec has
explicit examples where it is used for the build timestamp:

https://reproducible-builds.org/docs/source-date-epoch/

-- 
Bye, Peter Korsgaard