[GitHub] [incubator-nuttx] gustavonihei edited a comment on issue #3612: RV32: syslog/printf handling of 64-bit integers is broken

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gustavonihei edited a comment on issue #3612:
URL: https://github.com/apache/incubator-nuttx/issues/3612#issuecomment-827535446


   > https://github.com/apache/incubator-nuttx/blob/master/arch/risc-v/src/common/riscv_createstack.c#L50-L54
   > 
   > ```
   > #if defined(CONFIG_LIBC_FLOATINGPOINT) || defined (CONFIG_ARCH_RV64GC)
   > #  define STACK_ALIGNMENT   8
   > #else
   > #  define STACK_ALIGNMENT   4
   > #endif
   > ```
   > 
   > Look like RISCV always need 8 bytes alignment?
   
   Nice finding.
   Actually, the [calling convention](https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md#user-content--integer-calling-convention:~:text=The%20stack%20grows%20downwards%20(towards%20lower,are%20stored%20at%20correspondingly%20higher%20addresses.) states the following:
   
   >The stack grows downwards (towards lower addresses) and the stack pointer shall be aligned to a 128-bit boundary upon procedure entry. 
   
   So it seems that the correct `STACK_ALIGNMENT` should be 16.


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