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

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

On Fri, Feb 24, 2023 at 12:03:14PM +0000, Ian Abbott wrote:
> On 23/02/2023 15:42, Michael Olbrich wrote:
> > 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
> 
> Hi Michael,
> 
> Sorry to be a pain.  I'm attempting to inject extra CFLAGS through the
> toolchain wrappers, but I'm not sure how to do it.  Here is one of my
> attempts that does not work:
> 
> #
> ----------------------------------------------------------------------------
> # Prepare
> #
> ----------------------------------------------------------------------------
> 
> LIBTAHU_CONF_TOOL	:= NO
> 
> #
> ----------------------------------------------------------------------------
> # Compile
> #
> ----------------------------------------------------------------------------
> 
> # -D_TIME_BITS=64 requires -D_FILE_OFFSET_BITS=64
> LIBTAHU_CPPFLAGS := -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64
> LIBTAHU_CFLAGS := -O2
> LIBTAHU_MAKE_ENV := $(CROSS_ENV)
> # Just build the dynamic library.
> LIBTAHU_MAKE_OPT := \
> 	$(CROSS_ENV_PROGS) \
> 	lib/libtahu.so
> 
> $(STATEDIR)/libtahu.compile:
> 	@$(call targetinfo)
> 	@$(call world/compile, LIBTAHU)
> 	@$(call touch)
> 
> I'm obviously missing something to pass the properly wrapped CC and CPP
> variables (incorporating the extra flags) to 'make'.  Could you provide a
> clue how to fix it?

Are you sure it does not work? It will not be visible in the regular make
output. Run PTXdist with '-v' and then check platform-XXX/logfile.

You should find a 'wrapper: ...' line for each compiler run and the extra
flags should be visible here.

Michael


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