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

Wed Sep 29 17:23:30 PDT 2021

Hi Dimitri,

Great thanks for your info,  so would you mind to provide more info
about these macro for gcc and clang ?

Dimitri John Ledkov <dimitri.ledkov at canonical.com> 于2021年9月30日周四 上午6:21写道：
>
> Surely one can make this reproducible.
>
> If using compiler builtin macro, they respect environment variable of build time.
> Or in the make file one can use the reproducible builds timestamp environment variable (if available) and only otherwise call out date.
>
> Lots of other software do that already. Meaning they both encode build time, but also remain reproducible.

I guess you have seen one of them if there are lots, would you mind to
provide a example, I am curious about "encode build time" and "remain
reproducible" at the same time.

>
> On Wed, 29 Sep 2021, 11:20 , <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.
>>
>> 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
>> +
>>  $(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
>> 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
>>
>>
>> --
>> opensbi mailing list
>> opensbi at lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/opensbi