Serial ports are unavailable to the driver in the VM (VMware)
- From: "emusic" <eugene@xxxxxxxxxxxxxx>
- Date: 17 Sep 2006 01:04:43 -0700
I am debugging a driver that has some problems with standby/hiberation
support (PnP/power IRPs). So I cannot use WinDbg to remotely watch
driver messages. I have made a simple serial output and send my
debugging messages to the serial port using a direct registers access
(3f8-3ff). At another end, I use a virtual machine with a terminal
application or a log file.
Under VMware 4.x, all worked fine. Under VMware 5.5.2, serial port
registers seem to become unavailable to the driver after Windows boots
up. My driver successfully sends some messages after it started (a
boot-start) but stops to send them when Windows entered GUI mode.
SoftICE shows 0xFF read from any serial port register.
If I break into SoftICE immediately after it starts, serial port
registers behave correctly. If I break after Windows have booted, they
all show 0xFF.
If I open any application that accesses serial port, all works fine. If
I break into SoftICE and check port registers when such application is
opened, all registers behave correctly. But if I close the application,
all registers show 0xFF again.
I tried it in Windows 2000 SP4 and XP SP2, they behave the same way. I
tried to disable serial ports in Device Manages, but nothig was
changed. I looked for a port map in TSS but there is no port map in
kernel mode.
How can I gain a permanent access to serial port registers from the
driver? I need a direct access to be able to send a debug message in
any system state. It is a VMware or Windows problem?
Regards,
Eugene
.
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