From 27c5fe363ff9fd7278cce94c7fa739c38e5ba29c Mon Sep 17 00:00:00 2001
From: Martin Whitaker <pcmemtest@martin-whitaker.me.uk>
Date: Thu, 10 Dec 2020 12:52:58 +0000
Subject: [PATCH] Add startup option to enable/disable SMP.

---
 README.md    |  4 +++-
 app/config.c | 18 +++++++++++++++++-
 app/main.c   |  2 --
 system/smp.c |  6 ++++--
 system/smp.h |  2 +-
 5 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index c541136..8e40e92 100644
--- a/README.md
+++ b/README.md
@@ -99,13 +99,15 @@ the system was booted in UEFI mode, graphics mode must be used.
 
 Once booted, PCMemTest will initialise its display, then pause for a few
 seconds to allow the user to configure its operation. If no key is pressed,
-it will automatically start running all tests using all available CPU cores,
+it will automatically start running all tests using a single CPU core,
 continuing indefinitely until the user reboots or halts the machine.
 
 At startup, and when running tests, PCMemTest responds to the following keys:
 
   * F1
     * enters the configuration menu
+  * F2
+    * toggles detection and use of multiple CPU cores (SMP)
   * Space
     * toggles scroll lock (stops/starts error message scrolling)
   * Enter
diff --git a/app/config.c b/app/config.c
index 58b30a7..96426f3 100644
--- a/app/config.c
+++ b/app/config.c
@@ -586,9 +586,11 @@ void config_menu(bool initial)
 
 void initial_config(void)
 {
-    display_notice("Press <F1> to configure, <Enter> to start testing");
+    display_notice("Press <F1> to configure, <F2> to enable SMP, <Enter> to start testing ");
 
     bool got_key = false;
+    bool smp_enabled = false;
+    bool smp_init_done = false;
     for (int i = 0; i < 5000 && !got_key; i++) {
         usleep(1000);
         switch (get_key()) {
@@ -598,9 +600,20 @@ void initial_config(void)
             reboot();
             break;
           case '1':
+            smp_init(smp_enabled);
+            smp_init_done = true;
             config_menu(true);
             got_key = true;
             break;
+          case '2':
+            smp_enabled = !smp_enabled;
+            if (smp_enabled) {
+                display_notice("Press <F1> to configure, <F2> to disable SMP, <Enter> to start testing");
+            } else {
+                display_notice("Press <F1> to configure, <F2> to enable SMP, <Enter> to start testing ");
+            }
+            i = 0;
+            break;
           case ' ':
             toggle_scroll_lock();
             break;
@@ -611,4 +624,7 @@ void initial_config(void)
             break;
         }
     }
+    if (!smp_init_done) {
+        smp_init(smp_enabled);
+    }
 }
diff --git a/app/main.c b/app/main.c
index f57b743..0d5d0f5 100644
--- a/app/main.c
+++ b/app/main.c
@@ -155,8 +155,6 @@ static void global_init(void)
 
     error_init();
 
-    smp_init();
-
     initial_config();
 
     clear_message_area();
diff --git a/system/smp.c b/system/smp.c
index a55ac92..bcdde84 100644
--- a/system/smp.c
+++ b/system/smp.c
@@ -631,7 +631,7 @@ static smp_error_t start_cpu(int pcpu_num)
 // Public Functions
 //------------------------------------------------------------------------------
 
-void smp_init(void)
+void smp_init(bool smp_enable)
 {
     for (int i = 0; i < MAX_APIC_IDS; i++) {
         apic_id_to_pcpu_num[i] = 0;
@@ -644,7 +644,9 @@ void smp_init(void)
 
     num_pcpus = 1;
 
-    (void)(find_cpus_in_rsdp() || find_cpus_in_floating_mp_struct());
+    if (smp_enable) {
+        (void)(find_cpus_in_rsdp() || find_cpus_in_floating_mp_struct());
+    }
 
     for (int i = 0; i < num_pcpus; i++) {
         apic_id_to_pcpu_num[pcpu_num_to_apic_id[i]] = i;
diff --git a/system/smp.h b/system/smp.h
index 092113e..eb3de6a 100644
--- a/system/smp.h
+++ b/system/smp.h
@@ -39,7 +39,7 @@ extern int num_pcpus;
 /*
  * Initialises the SMP state and detects the number of physical CPUs.
  */
-void smp_init(void);
+void smp_init(bool smp_enable);
 
 /*
  * Starts the selected APs.