CCS/AM6548: Issue GCC v7.2.1 aarch64 using varargs for AM65xx

Hi Ruediger,

Do you use AM65x PSDK Linux, Linux-RT, RTOS or else?

Regards,
Pavel

I use AM65x TI-RTOS with processor_sdk_rtos_am65xx_5_02_00_10

Compiler call and flags are
"C:/ti/gcc-linaro-7.2.1-2017.11-i686-mingw32_aarch64-elf/bin/aarch64-elf-gcc.exe" -c -mcpu=cortex-a53+fp+simd -mtune=cortex-a53 -fno-exceptions -DAARCH64 -Dcore0 -DSOC_AM65XX -Dam6548 -Dam65xx_idk -I"C:/msol/src/multicarrier/mls_segcontroller/prj/prj_A53_main_test" -I"C:/ti/bios_6_75_01_05/packages/ti/posix/gcc" -I"C:/ti/gcc-linaro-7.2.1-2017.11-i686-mingw32_aarch64-elf/aarch64-elf/include" -I"C:/msol/src/multicarrier/mls_segcontroller/src" -I"C:/msol/src/multicarrier/mls_segcontroller/src/Include" -Og -g -gdwarf-3 -gstrict-dwarf -Wall -mabi=lp64 -mcmodel=large -mstrict-align -mfix-cortex-a53-835769 -mfix-cortex-a53-843419 -MMD -MP -MF"Diag/DiagPrint.d" -MT"Diag/DiagPrint.o" -std=c11 @"configPkg/compiler.opt" -o"Diag/DiagPrint.o" "C:/msol/src/multicarrier/mls_segcontroller/src/Diag/DiagPrint.c"

Regards,
Rüdiger

Hello Rudiger,
I think you should use
UART_printf(format, va_arg(vaArgPtr, int) );
instead of just
UART_printf(format, vaArgPtr);

BR
Michail

Hello Michail,
of course this would work, but only in this special case where an 'int' is used as 2nd argument.

But in fact my function App_print() shouldn't know with which arguments it has been called.
App_print() must be generic regarding arguments, because I wanted to forward it to vsnprintf() but that didn't work either.
I just reduced the problem to a very simple test case.

So I wonder if this is a gcc compiler bug.
I could paste the generated asm file if someone has experience with the Arm aarch64 procedure call rules.
see also [http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055c/IHI0055C_beta_aapcs64.pdf] Appendix B

Best regards,
Rüdiger

Hello Michail,

I don't think that my usage is so uncommon.

When you seach e.g. the AM65xx SDK for TIRTOS, you find the following functions doing exactly the same I did:

• pdk_am65xx_1_0_3\packages\ti\csl\example\esm\esm_clk_loss_test_app\esm_clk_loss_app.c 
  ESMApp_consoleprintf(const char *pcString, ...)
• pdk_am65xx_1_0_3\packages\ti\csl\example\mcan\mcanEvmLoopback\mcan_evm_loopback_app_main.c
  App_ConsolePrintf(const char *pcString, ...)
• pdk_am65xx_1_0_3\packages\ti\csl\example\rti\rti_dwwdtest_app\rti_app_dwwd_v1.c
  RTIAppUtilsPrint (const char *pcString, ...)
• pdk_am65xx_1_0_3\packages\ti\csl\test\mcanUt\testLib\st_mcanCommon.c
  App_ConsolePrintf(uint32_t type, uint32_t baseAddr, const char *pcString, ...)
• pdk_am65xx_1_0_3\packages\ti\drv\cal\examples\cal_capture_test\src\CaptureCal_main.c
  App_print(const char *format, ...)
• ... and many more 

But I found no example which I could compile+run for the AM65xx-IDK

In fact, forwarding varargs to vsnprintf() is very common. But this also doesn't work with the AM65xx: I get a memory exception.

Regards,

Rüdiger