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Re: How to access /dev/ttyS* ?

On 26/04/2012 4:04 PM, Corinna Vinschen wrote:
On Apr 26 11:48, Ryan Johnson wrote:
Hi all,

I'm trying to connect a VirtualBox guest's serial port to something
that cygwin/gdb can access for remote debugging, and am having
trouble connecting the pieces...

One post from a couple of years ago [1] suggests using /dev/ttyS* to
access COM ports. This would work great... except there are no
/dev/ttyS* on my install.
If the VM has a virtual HW serial port configured, you should see a
/dev/ttyS0 entry.  If it's not there, you didn't configure it.  Cygwin
in the guest can only access what is available in the guest OS.  If
there's a COM1, Cygwin has a /dev/ttyS0.
Ah, I'm trying to debug a linux guest from cygwin/win7 host. I guess the problem is my laptop doesn't have a physical COM1 port, so there's no way to route anything to it (and nothing for cygwin to display in /dev).

The other VirtualBox option is to create a named pipe (as in Windows
NPFS), and then wrap it into a pty using socat [2], but I can't
figure out how to access such a pipe from cygwin -- the "\\.\pipe\*"
path doesn't seem to be supported by cygpath and there's nothing
obvious in /dev/.
I don't know how that's supposed to work, but you could try to
connect it via /proc/sys/Device/NamedPipe/<name-of-named-pipe>
No guarantee that it works, though.
No love... I get "no such process." In retrospect I shouldn't have expected that to work, tho. Named pipes are undoubtedly very different beasts in Windows vs Posix.

It looks like my options are to run a second VM that points at the same named pipe and debug from within it, or use vmwaregateway [1] to convert it to TCP so my cygwin-based gdb can connect to it. Both work.


Thanks anyway,

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