Start adding parameters to syscall

1 files changed, 14 insertions, 3 deletions

diff --git a/arch/x86_64/src/context_switching/main.cpp b/arch/x86_64/src/context_switching/main.cpp
index 21299da..2a2a188 100644
--- a/arch/x86_64/src/context_switching/main.cpp
+++ b/arch/x86_64/src/context_switching/main.cpp
@@ -35,6 +35,11 @@ namespace teachos::arch::context_switching
     {
       video::vga::text::write("Successfully entered user mode!", video::vga::text::common_attributes::green_on_black);
 
+      uint64_t new_value = 60U;
+      asm volatile("mov %[input], %%rax"
+                   : /* no output from call */
+                   : [input] "r"(new_value)
+                   : "memory");
       asm volatile("syscall");
 
       video::vga::text::write("Successfully made a SYSCALL and returned back with SYSRETQ!",
@@ -43,10 +48,16 @@ namespace teachos::arch::context_switching
 
     auto syscall_handler() -> void
     {
-      uint64_t dummy{};
-      switch (dummy)
+      uint64_t syscall_number{};
+      asm volatile("mov %%rax, %[output]" : [output] "=r"(syscall_number));
+
+      switch (syscall_number)
       {
-        case 0:
+        case 1:
+          // Write VGA
+          break;
+        case 60U:
+          // Exit
           break;
         default:
           break;