[PATCH V2] Makefile: Add build time and compiler info string.

Wed Sep 29 06:36:44 PDT 2021

Hi Alistair

Great thanks for your review!

Alistair <alistair at alistair23.me> 于2021年9月29日周三 下午6:50写道：
>
> On Wed, Sep 29, 2021, at 8:19 PM, tekkamanninja at gmail.com wrote:
> > From: Wei Fu <wefu at 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 NEVER be used
> > in a real product.
>
> Thanks for the patch!
>
> I don't think we need to say NEVER, there are lots of products that don't use reproducible builds :)

Sure , s/NEVER/NOT/, or maybe

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 at redhat.com>
> > ---
> > Makefile           | 22 ++++++++++++++++++++++
> > README.md          | 23 +++++++++++++++++++++++
> > lib/sbi/sbi_init.c |  8 ++++++++
> > 3 files changed, 53 insertions(+)
> >
> > diff --git a/Makefile b/Makefile
> > index 16d9dca..a794c8d 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -150,6 +150,15 @@ 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_TIME_STAMP=$(shell date)
> > +OPENSBI_BUILD_COMPILER_VERSION=$(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 $(platform_src_dir) -iname "objects.mk" | sort -r; fi)
> > @@ -247,6 +256,10 @@ GENFLAGS += -I$(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 +411,12 @@ $(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
> > + $(call compile_cc,$@,$<)
> > + $(warning 'BUILD_INFO=y' violates 'reproducible builds', for DEBUG ONLY.)
> > +endif
>
> Do we need this?

yes, I have tested it. Without this, the time stamp will remain  the
time been built after 'make clean'
Because sbi_init.c may not been changed when you rebuild it .
so this change is for recompiling sbi_init.c every time , then
timestamp will be updated if you enable BUILD_INFO.

(I have mentioned below in the document)
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.

>
> > +
> > $(build_dir)/%.dep: $(src_dir)/%.S
> > $(call compile_as_dep,$@,$<)
> >
> > @@ -551,3 +570,6 @@ ifeq ($(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..86faa74 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. It should NEVER be used in a real
> > +product.
> > +
> > 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
> > \ No newline at end of file
>
> Probably want a new line here.
>
> Otherwise looks good.
>
> Alistair
>
> > diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
> > index f0eb365..ef00d9f 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);
> > }
> >
> > --
> > 2.25.4
> >
> >