[Qemu-devel] patch: emulate a `proper' null modem cable instead of a 3-wire one

[Juergen Lock]

The following makes a
        ttyd0   "/usr/libexec/getty std.9600"   dialup  on secure
/etc/ttys entry work for a FreeBSD guest.  Without it the emulated
serial port lacks carrier and hardware flow control and needs
        ttyd0   "/usr/libexec/getty 3wire.9600" dialup  on secure
which is not always what users expect. :)

Index: qemu/hw/serial.c
@@ -356,6 +356,7 @@
     s->irq = irq;
     s->lsr = UART_LSR_TEMT | UART_LSR_THRE;
     s->iir = UART_IIR_NO_INT;
+    s->msr = UART_MSR_DCD | UART_MSR_DSR | UART_MSR_CTS;
 
     register_savevm("serial", base, 1, serial_save, serial_load, s);
 
@@ -440,6 +441,7 @@
     s->irq = irq;
     s->lsr = UART_LSR_TEMT | UART_LSR_THRE;
     s->iir = UART_IIR_NO_INT;
+    s->msr = UART_MSR_DCD | UART_MSR_DSR | UART_MSR_CTS;
     s->base = base;
     s->it_shift = it_shift;