Re: [committed 0/2] CRIS: Fix compilation warnings that recent gcc treats as errors

[Torbjorn SVENSSON <torbjorn.svensson@foss.st.com>]

Hello Hans-Peter,

I finally had some time to go back to this topic.

On 2023-12-15 05:24, Hans-Peter Nilsson wrote:
>> Date: Wed, 6 Dec 2023 20:52:48 +0100
>> From: Torbjorn SVENSSON <torbjorn.svensson@foss.st.com>
>> What problems are there with the _getentropy stubs that I've submitted?
> 
> I hope to get into details later, as indicated by the "film
> at 11".  The problem is fairly visible with a standard
> test-run for cris-elf (with simulator and baseboard
> cris-sim): all libstdc++ tests fail with a linker warning,
> as its configure tests detect a presence of _getentropy but
> its reference trigs the stub warning (the .gnu.warning
> thing).  I *think* it's also visible for a build with
> arm-eabi+arm-sim which made me wonder how you configured and
> tested (you may have stated, I haven't looked).  Adding a
> patch to "prune" the stub-warning in libstdc++ prune.exp
> only exposes runtime errors when _getentropy is actually
> called.  Those errors are not present when _getentropy is
> not detected (and not used).


When I run the tests, I supply all the syscalls functions in my fixture 
to avoid the stubs warnings. This is nothing new to the _getentropy 
function though as the same problem is visible with for example _close.

If I try to link the following minimal C application with the 
arm-none-eabi target, I get the below warnings.

$ cat foo.c
int main() {
     return 0;
}


$ .../bin/arm-none-eabi-g++ -mcpu=cortex-m4 -mfloat-abi=soft -o foo.elf 
foo.c --specs=nosys.specs
.../bin/../lib/gcc/arm-none-eabi/14.0.0/../../../../arm-none-eabi/bin/ld: 
.../bin/../lib/gcc/arm-none-eabi/14.0.0/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp/libc.a(libc_a-closer.o): 
in function `_close_r':
(.text._close_r+0xc): warning: _close is not implemented and will always 
fail
.../bin/../lib/gcc/arm-none-eabi/14.0.0/../../../../arm-none-eabi/bin/ld: 
.../bin/../lib/gcc/arm-none-eabi/14.0.0/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp/libc.a(libc_a-lseekr.o): 
in function `_lseek_r':
(.text._lseek_r+0x10): warning: _lseek is not implemented and will 
always fail
.../bin/../lib/gcc/arm-none-eabi/14.0.0/../../../../arm-none-eabi/bin/ld: 
.../bin/../lib/gcc/arm-none-eabi/14.0.0/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp/libc.a(libc_a-readr.o): 
in function `_read_r':
(.text._read_r+0x10): warning: _read is not implemented and will always fail
.../bin/../lib/gcc/arm-none-eabi/14.0.0/../../../../arm-none-eabi/bin/ld: 
.../bin/../lib/gcc/arm-none-eabi/14.0.0/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp/libc.a(libc_a-writer.o): 
in function `_write_r':
(.text._write_r+0x10): warning: _write is not implemented and will 
always fail


Do you mean that you do not get these stub warnings for the cris-elf target?
If you do get them, in what way is _getentropy different from for 
example _close?

(the above is produced using newlib 7a45daa, GCC d0603dfe9 and binutils 
80d2ef0c4)

Kind regards,
Torbjörn