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

[Alistair]

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 :)

> 
> 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?

> +
> $(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
> 
>