fix gdt segments, improve idt and trial&error for triple fault

1 files changed, 18 insertions, 12 deletions

diff --git a/arch/x86_64/src/context_switching/main.cpp b/arch/x86_64/src/context_switching/main.cpp
index a5bd3fb..f449a3a 100644
--- a/arch/x86_64/src/context_switching/main.cpp
+++ b/arch/x86_64/src/context_switching/main.cpp
@@ -10,24 +10,30 @@ namespace teachos::arch::context_switching
 {
   auto initialize_descriptor_tables() -> descriptor_tables
   {
+    kernel::cpu::clear_interrupt_flag();
     decltype(auto) global_descriptor_table = segment_descriptor_table::initialize_global_descriptor_table();
     decltype(auto) interrupt_descriptor_table = interrupt_descriptor_table::initialize_interrupt_descriptor_table();
 
-    kernel::cpu::far_pointer pointer{&boot::reload_segment_register, 1 * sizeof(segment_descriptor_table::segment_descriptor)};
-    asm volatile("rex64 lcall *%[far_function_pointer]" : : [far_function_pointer] "m" (pointer));
+    kernel::cpu::far_pointer pointer{&boot::reload_segment_register,
+                                     1 * sizeof(segment_descriptor_table::segment_descriptor)};
+    asm volatile("rex64 lcall *%[far_function_pointer]" : : [far_function_pointer] "m"(pointer));
 
-    // // Load task state segment descriptor from the last element in the global descriptor table, done by calculating
-    // // offset in bytes to the start of the segment descriptor (5 * 16) = 80
-    // uint16_t const tss_selector =
-    //     (global_descriptor_table.size() - 1) * sizeof(segment_descriptor_table::segment_descriptor);
-    // kernel::cpu::load_task_register(tss_selector);
+    // Load task state segment descriptor from the last element in the global descriptor table, done by calculating
+    // offset in bytes to the start of the segment descriptor (5 * 16) = 80
+    uint16_t const tss_selector =
+        (global_descriptor_table.size() - 1) * sizeof(segment_descriptor_table::segment_descriptor);
+    kernel::cpu::load_task_register(tss_selector);
 
-    // auto const stored_task_register = kernel::cpu::store_task_register();
-    // arch::exception_handling::assert(tss_selector == stored_task_register,
-    //                                  "[Global Descriptor Table] Loaded TR value is not the same as the stored value.");
+    auto const stored_task_register = kernel::cpu::store_task_register();
+    arch::exception_handling::assert(tss_selector == stored_task_register,
+                                     "[Global Descriptor Table] Loaded TR value is not the same as the stored value.");
 
-    // FIXME: We currently cannot enable interrupts, since for some reason, we will later run into what looks like a GP. Maybe because no IDT is loaded? Maybe our boot code segment is not set up correctly?
-    // kernel::cpu::set_interrupt_flag();
+    // FIXME: We currently cannot enable interrupts, since for some reason, we will later run into what looks like a GP
+    // and triple fault.
+
+    // @MTO: SOMETIMES i get past a breakpoint here???? seems to happen when i actually pause before (f.e. inside the
+    // idt). NEVER happened when stepping through quickly. Can you reproduce this?
+    kernel::cpu::set_interrupt_flag();
 
     descriptor_tables tables = {global_descriptor_table, interrupt_descriptor_table};
     return tables;