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

Anup Patel anup at brainfault.org
Sun Oct 17 23:17:27 PDT 2021 

On Mon, Oct 18, 2021 at 11:27 AM Bin Meng <bmeng.cn at gmail.com> wrote:
>
> Hi Anup,
>
> On Mon, Oct 18, 2021 at 12:13 PM Anup Patel <anup.patel at wdc.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 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 at redhat.com>
> > Reviewed-by: Anup Patel <anup.patel at 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

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