From: Player, Timmons <timmons.pla...@spirent.com>
Committer: Nadav Har'El <n...@scylladb.com>
Branch: master
drivers/isa-serial.cc: Prevent spinning under VMWare.
The Line Status Register (LSR) of non-existant serial ports under VMWare
(and maybe other platforms) returns 0xff. Ignore this value instead
of polling for terminal characters that aren't there.
Fixes #567.
Signed-off-by: Timmons C. Player <timmons.pla...@spirent.com>
Message-Id: <e96fc58e-fd03-4cf3-bd80-d2405f9fd...@spirent.com>
---
diff --git a/drivers/isa-serial.cc b/drivers/isa-serial.cc
--- a/drivers/isa-serial.cc
+++ b/drivers/isa-serial.cc
@@ -82,7 +82,9 @@ void isa_serial_console::write(const char *str, size_t
len)
bool isa_serial_console::input_ready()
{
u8 val = pci::inb(ioport + regs::LSR);
- return val & lsr::RECEIVE_DATA_READY;
+ // On VMWare hosts without a serial port, this register always
+ // returns 0xff. Just ignore it instead of spinning incessantly.
+ return (val != 0xff && (val & lsr::RECEIVE_DATA_READY));
}
char isa_serial_console::readch()
--
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