[GitHub] [incubator-nuttx] Ouss4 commented on a change in pull request #5261: xtensa: add svccall handler and use svc call in context switch

[GitBox <gi...@apache.org>]

Ouss4 commented on a change in pull request #5261:
URL: https://github.com/apache/incubator-nuttx/pull/5261#discussion_r790302830



##########
File path: arch/xtensa/src/common/xtensa_svcall.c
##########
@@ -94,8 +101,71 @@ int xtensa_svcall(int irq, void *context, void *arg)
 
       case SYS_save_context:
         {
+          DEBUGASSERT(regs[REG_A3] != 0);

Review comment:
       I see that `SYS_save_context` is equal to 0.  The TRM recommends to keep this syscall command to spill the register windows, to have a certain portability between different OSes.

##########
File path: arch/xtensa/include/syscall.h
##########
@@ -29,10 +29,33 @@
  * Included Files
  ****************************************************************************/
 
+#include <nuttx/config.h>
+#include <debug.h>
+#include <arch/irq.h>
+
+#ifndef __ASSEMBLY__
+#  include <stdint.h>
+#endif
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
 
+/* This is the value used as the argument to the SVC instruction.

Review comment:
       ```suggestion
   /* This is the value used as the argument to the SYSCALL instruction.
   ```




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