Don't enable interrupts prior to IVT and PIC setup

The machine may crash if an interrupt occurs prior to the setup of the
interrupt vector table (IVT) and programmable interrupt controller
(PIC).  This patch makes sure that interrupts remain disabled until
these components are setup.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

4 files changed, 11 insertions, 7 deletions

diff --git a/src/fw/csm.c b/src/fw/csm.c
index 7cdb398f..aee2f90e 100644
--- a/src/fw/csm.c
+++ b/src/fw/csm.c
@@ -183,6 +183,7 @@ handle_csm_0002(struct bregs *regs)
     struct bios_data_area_s *bda = MAKE_FLATPTR(SEG_BDA, 0);
     bda->hdcount = 0;
 
+    thread_setup();
     mathcp_setup();
     timer_setup();
     clock_setup();
diff --git a/src/post.c b/src/post.c
index 6157b507..8cb7b7cb 100644
--- a/src/post.c
+++ b/src/post.c
@@ -124,7 +124,6 @@ interface_init(void)
     bda_init();
 
     // Other interfaces
-    thread_init();
     boot_init();
     bios32_init();
     pmm_init();
@@ -167,6 +166,7 @@ platform_hardware_setup(void)
 
     // Init base pc hardware.
     pic_setup();
+    thread_setup();
     mathcp_setup();
     timer_setup();
     clock_setup();
diff --git a/src/stacks.c b/src/stacks.c
index 1dbdfe9b..1ad9ef09 100644
--- a/src/stacks.c
+++ b/src/stacks.c
@@ -558,12 +558,13 @@ getCurThread(void)
     return (void*)ALIGN_DOWN(esp, THREADSTACKSIZE);
 }
 
-static int ThreadControl;
+static u8 CanInterrupt, ThreadControl;
 
 // Initialize the support for internal threads.
 void
-thread_init(void)
+thread_setup(void)
 {
+    CanInterrupt = 1;
     if (! CONFIG_THREADS)
         return;
     ThreadControl = romfile_loadint("etc/threads", 1);
@@ -673,11 +674,12 @@ void
 yield(void)
 {
     if (MODESEGMENT || !CONFIG_THREADS) {
-        check_irqs();
+        if (MODESEGMENT || CanInterrupt)
+            check_irqs();
         return;
     }
     struct thread_info *cur = getCurThread();
-    if (cur == &MainThread)
+    if (cur == &MainThread && CanInterrupt)
         // Permit irqs to fire
         check_irqs();
 
@@ -705,7 +707,8 @@ yield_toirq(void)
         yield();
         return;
     }
-    wait_irq();
+    if (MODESEGMENT || CanInterrupt)
+        wait_irq();
 }
 
 // Wait for all threads (other than the main thread) to complete.
diff --git a/src/stacks.h b/src/stacks.h
index 82c4c3c8..a3b031ce 100644
--- a/src/stacks.h
+++ b/src/stacks.h
@@ -28,7 +28,7 @@ extern struct thread_info MainThread;
 struct thread_info *getCurThread(void);
 void yield(void);
 void yield_toirq(void);
-void thread_init(void);
+void thread_setup(void);
 int threads_during_optionroms(void);
 void run_thread(void (*func)(void*), void *data);
 void wait_threads(void);