I have some new insights about what happened here.
The compiler warnings in nx_start.c that were the reason I started this thread:
init/nx_start.c: In function 'nx_start':
init/nx_start.c:552:14: warning: unused variable 'heap_size' [-Wunused-variable]
size_t heap_size;
^~~~~~~~~
init/nx_start.c:551:17: warning: unused variable 'heap_start'
[-Wunused-variable]
FAR void *heap_start;
^~~~~~~~~~
These warnings were appearing when I built my custom board
configuration, based on a Tiva chip.
When I switched to the tm4c1294-launchpad:nsh configuration, based on
the same Tiva chip, the warnings disappeared!
Comparing the two boards' defconfig files, and then their .config
files, I saw no differences that should change the presence of the
define MM_KERNEL_USRHEAP_INIT.
To help diagnose why the two configurations behaved differently, I
added the following to mm.h, just below the define of
MM_KERNEL_USRHEAP_INIT:
#if defined(CONFIG_BUILD_KERNEL)
#warning "CONFIG_BUILD_KERNEL is defined"
#else
#warning "CONFIG_BUILD_KERNEL is NOT defined"
#endif
#if defined(__KERNEL__)
#warning "__KERNEL__ is defined"
#else
#warning "__KERNEL__ is NOT defined"
#endif
#if defined(MM_KERNEL_USRHEAP_INIT)
#warning "MM_KERNEL_USRHEAP_INIT is defined"
#else
#warning "MM_KERNEL_USRHEAP_INIT is NOT defined"
#endif
and ran make, redirecting stdout and stderr to a file. This produced a
ton of output, but I saw that in both configurations, some files were
built with __KERNEL__ defined, which causes MM_KERNEL_USRHEAP_INIT to
be defined, and others were built without __KERNEL__ defined, which
causes MM_KERNEL_USRHEAP_INIT to be undefined.
The difference between the two configurations is that in my custom
board, nx_start.c was being built without __KERNEL__ defined, whereas
in tm4c1294-launchpad, nx_start.c was built *with* __KERNEL__ defined.
After much more head-scratching, I finally traced this to a change in
commit # 459ad9937377a42785692098ff0d73baaa9551e6:
commit 459ad9937377a42785692098ff0d73baaa9551e6
Author: liuhaitao <[email protected]>
Date: Fri Apr 10 10:37:54 2020 +0800
Use EXTRAFLAGS instead of EXTRADEFINES to be used by make via command line
So call 'make EXTRAFLAGS=-Wno-cpp' could suppress the warnings
with pre-processor
directive #warning in GCC.
Change-Id: Iaa618238924c9969bf91db22117b39e6d2fc9bb6
Signed-off-by: liuhaitao <[email protected]>
All other boards' Make.defs were updated during that change to
$(EXTRAFLAGS) but my custom boards remained with $(EXTRADEFINES).
So: If anyone else with custom board configurations sees the warnings
at the top of this email, look to see if you've updated your custom
Make.defs for the EXTRADEFINES -> EXTRAFLAGS change.
Apparently, __KERNEL__ gets defined (or not defined) differently for
some files than for others. Evidently it comes from EXTRAFLAGS when
building nx_start.c, but it comes from elsewhere when building files
in arch/arm/src/armv7-m.
Anyway mystery solved. I'll go create that PR now.
Cheers,
Nathan
