diff options
Diffstat (limited to 'na/drivers')
| -rw-r--r-- | na/drivers/uart.cc | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/na/drivers/uart.cc b/na/drivers/uart.cc index 6a35588..2e553d6 100644 --- a/na/drivers/uart.cc +++ b/na/drivers/uart.cc @@ -15,10 +15,21 @@ static uint64 g_uart_pa = 0; static uint64 g_uart_size = 0; +static bool g_runtime_mapping_ready = false; extern "C" void early_putc(char c) { if (!g_uart_pa) return; - volatile auto* uart = reinterpret_cast<volatile uint8*>(pa_to_va(phys_addr(g_uart_pa)).raw); + + /* + * Before vmm_init() activates the final page table, UART MMIO is only + * reachable via the bootstrap fixed direct map from entry.S. + * After activation, switch to the runtime (possibly KASLR-slid) base. + */ + uint64 uart_va = g_runtime_mapping_ready + ? pa_to_va(phys_addr(g_uart_pa)).raw + : boot_pa_to_va(phys_addr(g_uart_pa)).raw; + + volatile auto* uart = reinterpret_cast<volatile uint8*>(uart_va); *uart = static_cast<uint8>(c); } @@ -45,3 +56,7 @@ void console_init() { vmm_map_kernel_mmio(g_uart_pa, g_uart_size); } } + +void console_use_runtime_mapping() { + g_runtime_mapping_ready = true; +} |