[PATCH V4] Makefile: Add build time and compiler info string

[Jessica Clarke]

On 1 Oct 2021, at 17:08, Bin Meng <bmeng.cn at gmail.com> wrote:
> 
> Hi Wei,
> 
> On Thu, Sep 30, 2021 at 6:12 PM <wefu at redhat.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".
>> 
>> Signed-off-by: Wei Fu <wefu at redhat.com>
>> ---
>> Makefile           | 31 +++++++++++++++++++++++++++++++
>> README.md          | 23 +++++++++++++++++++++++
>> lib/sbi/sbi_init.c |  8 ++++++++
>> 3 files changed, 62 insertions(+)
>> 
>> diff --git a/Makefile b/Makefile
>> index 16d9dca..0158e89 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
> 
> This hour/minute/second format seems uncommon. Also for %Z it is
> ambiguous and not better than %z, e.g.: CST could mean different time
> zones.

-u is passed to date so it will always be UTC.

Jess