Kernel/Graphics: Unblank the screen when initializing bochs display

Author: https://github.com/supercomputer7
Commit: https://github.com/SerenityOS/serenity/commit/00e4cc23cbf
Pull-request: https://github.com/SerenityOS/serenity/pull/8399
Reviewed-by: https://github.com/alimpfard ✅

Kernel/Graphics/BochsGraphicsAdapter.cpp

@@ -65,6 +65,11 @@ UNMAP_AFTER_INIT BochsGraphicsAdapter::BochsGraphicsAdapter(PCI::Address pci_add
     auto id = PCI::get_id(pci_address);
     if (id.vendor_id == 0x80ee && id.device_id == 0xbeef)
         m_io_required = true;
+
+    // FIXME: Although this helps with setting the screen to work on some cases,
+    // we need to check we actually can access the VGA MMIO remapped ioports before
+    // doing the unblanking.
+    unblank();
     set_safe_resolution();
 }
 
@@ -82,6 +87,14 @@ GraphicsDevice::Type BochsGraphicsAdapter::type() const
     return Type::Bochs;
 }
 
+void BochsGraphicsAdapter::unblank()
+{
+    auto registers = map_typed_writable<volatile BochsDisplayMMIORegisters>(m_mmio_registers);
+    full_memory_barrier();
+    registers->vga_ioports[0] = 0x20;
+    full_memory_barrier();
+}
+
 void BochsGraphicsAdapter::set_safe_resolution()
 {
     VERIFY(m_framebuffer_console);

Kernel/Graphics/BochsGraphicsAdapter.h

@@ -46,6 +46,7 @@ private:
     explicit BochsGraphicsAdapter(PCI::Address);
 
     void set_safe_resolution();
+    void unblank();
 
     bool validate_setup_resolution(size_t width, size_t height);
     u32 find_framebuffer_address();