cannot find value `RTS_PULSE_WIDTH` in this scope

[wangzhankun]

我已经配置好rust的环境了，当执行just run的时候部分报错如下：

   Compiling user_lib v0.1.0 (/root/rv-n-ext-impl/rCore-N/user)
error[E0425]: cannot find value `RTS_PULSE_WIDTH` in this scope
   --> src/user_uart.rs:279:50
    |
279 |                         if self.rx_fifo_count == RTS_PULSE_WIDTH {
    |                                                  ^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find value `RTS_PULSE_WIDTH` in this scope
   --> src/user_uart.rs:281:57
    |
281 |                         } else if self.rx_fifo_count == RTS_PULSE_WIDTH * 2 {
    |                                                         ^^^^^^^^^^^^^^^ not found in this scope

[wangzhankun]

在rCore-N/user/src/user_uart.rs中，如果启用的是board_qemu feature，就会导致serial_config中不存在RTS_PULSE_WIDTH变量，是否应该添加这个变量呢？如果添加的话，变量的值应该是多少呢？

#[cfg(feature = "board_qemu")]
mod serial_config {
    pub use uart8250::{uart::LSR, InterruptType, MmioUart8250};
    pub type SerialHardware = MmioUart8250<'static>;
    pub const FIFO_DEPTH: usize = 16;
    pub const SERIAL_NUM: usize = 4;
    pub const SERIAL_BASE_ADDRESS: usize = 0x1000_2000;
    pub const SERIAL_ADDRESS_STRIDE: usize = 0x1000;
    pub fn irq_to_serial_id(irq: u16) -> usize {
        match irq {
            12 => 0,
            13 => 1,
            14 => 2,
            15 => 3,
            _ => 0,
        }
    }
}

#[cfg(feature = "board_lrv")]
mod serial_config {
    pub use uart_xilinx::uart_16550::{uart::LSR, InterruptType, MmioUartAxi16550};
    pub type SerialHardware = MmioUartAxi16550<'static>;
    pub const FIFO_DEPTH: usize = 16;
    pub const RTS_PULSE_WIDTH: usize = 8;
    pub const SERIAL_NUM: usize = 4;
    pub const SERIAL_BASE_ADDRESS: usize = 0x6000_1000;
    pub const SERIAL_ADDRESS_STRIDE: usize = 0x1000;
    pub fn irq_to_serial_id(irq: u16) -> usize {
        match irq {
            4 => 0,
            5 => 1,
            6 => 2,
            7 => 3,
            _ => 0,
        }
    }
}