Add debug output for qemu vga driver, still not working...

Signed-off-by: Harry Chen <i@harrychen.xyz>

kernel/src/drivers/gpu/qemu_stdvga.rs

@@ -22,6 +22,7 @@ const PCIM_CMD_MEMEN: u32 = 0x0002;
 fn pci_read_config(pci_base: usize, bus: u8, slot: u8, func: u8, offset: u8) -> u32 {
     // write config address
     let address = (1 << 31) | ((bus as u32) << 16) | ((slot as u32) << 11) | ((func as u32) << 8) | (offset as u32);
+    println!("Address: {:08x}", address);
     write(pci_base + 0xcf8, address);
     // do the actual work
     read(pci_base + 0xcfc)
@@ -38,9 +39,14 @@ fn pci_write_config(pci_base: usize, bus: u8, slot: u8, func: u8, offset: u8, va
 pub fn init(pci_base: usize, vga_base: usize, x_res: u16, y_res: u16) {
 
     // enable PCI MMIO
+    let pci_vendor = pci_read_config(pci_base, 0x00, 0x12, 0x00, 0x0);
+    println!("PCI Device ID: {:08x}", pci_vendor);
+
     let pci_state = pci_read_config(pci_base, 0x00, 0x12, 0x00, PCIR_COMMAND);
+    println!("PCI Config Status: {:08x}", pci_state);
     pci_write_config(pci_base, 0x00, 0x12, 0x00, PCIR_COMMAND, pci_state | PCIM_CMD_PORTEN | PCIM_CMD_MEMEN);
 
+
     // vga operations
     let vga_write_io = |offset: u16, value: u8| {
         write(vga_base + VGA_MMIO_OFFSET + (offset as usize), value);
@@ -61,8 +67,9 @@ pub fn init(pci_base: usize, vga_base: usize, x_res: u16, y_res: u16) {
     vga_write_vbe(VBE_DISPI_INDEX_YRES, y_res);
     vga_write_vbe(VBE_DISPI_INDEX_BPP, 8);
     // enable vbe
-    let vbe_enable = vga_read_vbe(VBE_DISPI_INDEX_ENABLE) | VBE_DISPI_ENABLED;
+    let vbe_enable = vga_read_vbe(VBE_DISPI_INDEX_ENABLE);
-    vga_write_vbe(VBE_DISPI_INDEX_ENABLE, vbe_enable);
+    println!("VBE Status: {:04x}", vbe_enable);
+    vga_write_vbe(VBE_DISPI_INDEX_ENABLE, vbe_enable | VBE_DISPI_ENABLED);
 
     println!("QEMU STDVGA driver initialized @ {:x}", vga_base);