Hi Y.HB 

LDFLAGS sets both the library kind to include in the archive build but it also 
uses the -L flags to know where to look for it. The -lm can mean the libm.a. 
libm.so libm.la so it searches the LD_LIBRARY_PATH environment variable to find 
one that fits. If you want expressly to include the libm.a you should specify 
it instead of -lm. The first thing I recommend is find the symbols inside the 
Makefile configured for the . Look for the LDFLAGS and then your 
LD_LIBRARY_PATH to see if it matches where that arm-rtems5/lib/libm.a is. 

You can even use the flag argument: arm-rtems5/lib/libm.a or 
./arm-rtems5/lib/libm.a to express the precise library and location to use. 

This is one important distinction that many people confuse about how automake 
and autoconf work: There is no "internal logic" in the autotools way of 
creating recipes for Makefiles. m4 is used for pattern processing. You must 
express what you want it to make, it won't go looking anywhere else than what 
is specified. 

It's not cmake, scons, or raw make. GNU Autotools creates recipe files, like 
config.status, that just hold environmental variables. 

DaemonDave on github. 


From: "Y. HB" <sprh...@gmail.com> 
To: "rtems-us...@rtems.org" <users@rtems.org> 
Sent: Friday, July 22, 2022 12:11:38 AM 
Subject: Re: How can I add LDFLAGS for bsp build? 

I added -lm in LDFLAGS in my custom bsps/arm/tms570/config/xxx.cfg 

the flag is added to compiling arguments, but it still reported undefined 
reference to 'floor', but I see there is floor symbols in the 
arm-rtems5/lib/libm.a 

Why is it? 

Thanks 

On Fri, Jul 22, 2022 at 1:43 PM Y. HB < [ mailto:sprh...@gmail.com | 
sprh...@gmail.com ] > wrote: 



Hello 

I'm working on a custom tms570 bsp upon RTEMS 5.1, but it depends on math lib 
(-lm), how can I add this flag to the bsp build? 

Shall I add LDFLAGS="-lm" during configure or shall I change some variables in 
c/src/lib/libbsp/arm/xxxx/Makefile.am? 

Thanks 




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