Colin Percival 1c60b24baa Add a loader tunable "hw.broken_txfifo" which enables a workaround for a ... bug in old versions of QEMU (and Xen, and other places using QEMU code). On those buggy emulated UARTs, the "TX idle" interrupt gets lost; with this workaround, we spinwait for the TX to happen and then send ourselves the interrupt. It's ugly but it works, while minimizing the impact on the code for the !broken_txfifo case. MFC after: 2 weeks		2013-01-27 23:33:42 +00:00
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uart_bus_acpi.c
uart_bus_ebus.c
uart_bus_fdt.c
uart_bus_isa.c
uart_bus_pccard.c
uart_bus_pci.c
uart_bus_puc.c
uart_bus_scc.c
uart_bus.h
uart_core.c
uart_cpu_ia64.c
uart_cpu_pc98.c
uart_cpu_powerpc.c
uart_cpu_sparc64.c
uart_cpu_x86.c
uart_cpu.h
uart_dbg.c
uart_dev_lpc.c
uart_dev_ns8250.c
uart_dev_pl011.c
uart_dev_quicc.c
uart_dev_sab82532.c
uart_dev_z8530.c
uart_if.m
uart_kbd_sun_tables.h
uart_kbd_sun.c
uart_kbd_sun.h
uart_subr.c
uart_tty.c
uart.h