Re: [ptxdist] [PATCH] libtahu: Change CFLAGS to use 64-bit system time

[Michael Olbrich <m.olbrich@pengutronix.de>]

On Mon, Feb 20, 2023 at 01:41:05PM +0000, Ian Abbott wrote:
> libtahu exposes a library function `get_current_timestamp()` to return
> the real-time clock as the number of milliseconds since the Unix epoch
> as a 64-bit value.  It calls `clock_gettime(CLOCK_REALTIME, &ts)` (where
> `ts` is a `struct timespec`) to get the system time and does some simple
> arithmetic on `ts.tv_sec` and `ts.tv_nsec` to convert the time to a
> number of milliseconds.
> 
> Ideally, we want `ts.tv_sec` to have a 64-bit type to avoid Y2038
> problems, but on most 32-bit architectures, `ts.tv_sec` will have a
> 32-bit type by default.  Try and select the 64-bit time interface even
> on 32-bit architectures by appending `-D_FILE_OFFSET_BITS=64` and
> `-D_TIME_BITS=64` to the `CFLAGS` variable when invoking `make`.  This
> works for glibc 2.34 or later when the system is running on Linux kernel
> 5.1 or later.
> 
> Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
> ---
>  rules/libtahu.make | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/rules/libtahu.make b/rules/libtahu.make
> index 26c064c6d..3e392216d 100644
> --- a/rules/libtahu.make
> +++ b/rules/libtahu.make
> @@ -37,11 +37,12 @@ LIBTAHU_CONF_TOOL	:= NO
>  # Compile
>  # ----------------------------------------------------------------------------
>  
> -#LIBTAHU_MAKE_ENV	:= $(CROSS_ENV)
> -
> +LIBTAHU_CPPFLAGS := -Iinclude -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64
> +LIBTAHU_CFLAGS := -O2 -g -g3 -fPIC

No need to mess with the existing CFLAGS. You can inject extra CFLAGS
though the toolchain wrappers. And for correctness, make it conditional:

ifdef PTXCONF_GLOBAL_LARGE_FILE
LIBTAHU_CFLAGS := -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64
endif

nothing else is needed.

Michael

>  # Just build the dynamic library.
>  LIBTAHU_MAKE_OPT	:= \
>  	$(CROSS_ENV_PROGS) \
> +	CFLAGS='$(CROSS_CPPFLAGS) $(LIBTAHU_CPPFLAGS) $(CROSS_CFLAGS) $(LIBTAHU_CFLAGS)' \
>  	lib/libtahu.so
>  
>  # ----------------------------------------------------------------------------
> -- 
> 2.39.1
> 
> 
> 

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